194 results on '"Brian Morton"'
Search Results
2. The origins, relationships, evolution and conservation of the weirdest marine bivalves: The watering pot shells. A review
- Author
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Fabrizio Marcondes Machado and Brian Morton
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Ligament structure ,Fossil Record ,biology ,Ecology ,Convergent evolution ,Morphology (biology) ,Lyonsiidae ,biology.organism_classification ,Bivalvia ,Cenozoic ,Clavagellidae - Abstract
The fossil record shows that the two clavagelloid or watering pot families evolved at different times, the Clavagellidae first in the late Mesozoic (100–66 mya), the Penicillidae later in the Cenozoic (33–23 mya)—the former originally with, thus, a near-global Tethyan distribution, the latter restricted to the Indo-West Pacific. Representatives of the two clavagelloid families, moreover, have wholly different adventitious tube/crypt structures and, thus, methods of formation suggesting that evolutionary experiments have been undertaken to achieve such radical architectural novelties. This has resulted in one of the most surprising examples of convergent evolution in the Bivalvia. But, what were the ancestors of the Clavagelloidea? The shell and internal morphology of representatives of the three recognized genera of the Lyonsiidae, that is, Lyonsia, Entodesma and Mytilimeria, are described. Species of the latter two genera are highly specialized epibenthic, byssate, nestlers and embedded symbionts of ascidian colonies and sponges, respectively. Species of Lyonsia, however, are mostly shallow endobenthic burrowers. On the basis of these studies, it is concluded that species of Lyonsia can be regarded as representative of the ancestral watering pot (Clavagelloidea) condition. Evidence for this conclusion include the mineralogy, characteristics and ligament structure of the shell and features of the anatomy, importantly the modification of the vestigial pedal retractor muscles to form simple (Clavagellidae) and more complex (Penicillidae) proprioreceptors. Such an anatomy-based conclusion is supported to some extent by DNA analyses of representatives of the Lyonsiidae and the two constituent families of the Clavagelloidea. To some extent because all clavagelloids are exceedingly rare hindering such analyses. Such rarity, however, also argues for the strict conservation of all the species of the Clavagelloidea.
- Published
- 2021
3. An improbable opportunistic predator: the functional morphology ofPinna nobilis(Bivalvia: Pterioida: Pinnidae)
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Brian Morton and Sanja Puljas
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0106 biological sciences ,Pinnidae ,biology ,Obligate ,010604 marine biology & hydrobiology ,Proteolytic enzymes ,Zoology ,pallial gland ,sulphuric acid ,buccal gland ,proteolytic enzymes ,stomach structure and contents ,Aquatic Science ,biology.organism_classification ,Bivalvia ,010603 evolutionary biology ,01 natural sciences ,Predation ,stomatognathic system ,Predator ,Pinna nobilis ,Pterioida - Abstract
The functional morphology ofPinna nobilisis described, with special reference to the uniquely pinnid pallial organ, the similarly unique buccal (formerly pallial) gland, the stomach and its contents. The pallial gland produces sulphuric acid which as well as functioning as a shell cleaning swab may be involved in prey capture. The buccal gland discharging into the oesophagus has proteolytic digestive functions while the stomach is adapted for the reception and digestion of captured, mucous-bound, mesozooplanktonic and epi- and endo-benthic, prey items.Pinna nobilisis thus not simply either an accidental or incidental predator of such species but is opportunistic. The buccal glands and stomachs of other Pinnidae are not so specialized as inP. nobilis,possibly indicating that in the particular, oligotrophic, environment of the Mediterranean and Adriatic Seas, and in which it is endemic,P. nobilishas, in addition to being a typical ctenidial suspension feeder, become an opportunistic predator. Although the deep sea representatives of the Septibranchia (Anomalodesmata) and Propeamussidae are obligate predators, this is the first record of any bivalve functioning as an opportunistic predator with unique morphological adaptations to facilitate this.
- Published
- 2018
4. The Biology and Functional Morphology ofCurvemysella paula(A. Adams, 1856) (Bivalvia: Galeommatoidea: Montacutidae) Commensal withDiogenes goniochirusForest, 1956 (Crustacea: Paguridea) on China Beach, Danang, Vietnam
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Brian Morton
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0106 biological sciences ,Columella ,biology ,Ecology ,010604 marine biology & hydrobiology ,Marine larval ecology ,Aquatic Science ,biology.organism_classification ,Bivalvia ,Hermit crab ,010603 evolutionary biology ,01 natural sciences ,Crustacean ,Taxon ,Hermaphrodite ,Genus ,Ecology, Evolution, Behavior and Systematics - Abstract
The Indo-West Pacific montacutid Curvemysella paula(A. Adams, 1856) is the sole representative of its genus and the only known bivalve that is an obligate commensal of hermit crabs. As such, studies on it are accordingly very few. It lives in small groups byssally attached to the internal columella of the host's adopted shell. This paper describes the species from a wave-exposed beach in central Vietnam at Danang. Here, it was living with Diogenes goniochirus, but elsewhere in Hong Kong and Japan other taxa serve as hosts. The adult shell of C. paula is antero-ventrally long, deeply concave ventrally and so inequivalve as to appear twisted. Smaller individuals are more equivalve and equilateral and become deformed with age and growth. The hinge plate has a structure typical of the Montacutidae with the ligament ventrally formed into a lithodesma. Anatomically, C. paula is also unremarkable and interest in it focuses on reproduction. The species lives in small groups, the oldest and largest being a female, the smallest and youngest males. Intermediate sized individuals are hermaphroditic. Curvemysella paula is thus a protandric consecutive hermaphrodite. Prodissoconch morphology suggests that C. paula does not ctenidially brood fertilised eggs or, if so, only briefly. Further, it seems likely that there is subsequently an abbreviated lecithotrophic period of development perhaps undertaken close to the sea bed - thereby keeping the larvae close to established hermit crab and parental bivalve populations.
- Published
- 2017
5. Predatory marine bivalves: A review
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Brian Morton and Fabrizio Marcondes Machado
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0106 biological sciences ,Intoxicative inhalant ,Larva ,biology ,010604 marine biology & hydrobiology ,Ctenidium ,Zoology ,biology.organism_classification ,01 natural sciences ,Crustacean ,Deep sea ,Life history theory ,Predation ,Phylogenetics - Abstract
Most bivalves are suspension feeders. On the deep sea floor, however, some are predators, typically of meiobenthic crustaceans: copepods, cumaceans and ostracods. Propeamusiid scallops are one such group of predators. The largest numbers of predators, however, belong to the bivalve subclass Anomalodesmata and constitute, as currently recognised, some 500 species belonging principally to the Verticordioidea (120), Poromyoidea (75) and Cuspidarioidea (304) with four, two and four constituent families, respectively. A further family, the Parilimyidae, is considered to be derived from the Pholadomyoidea-the anomalodesmatan ancestor. These, generally small (
- Published
- 2019
6. Influence of predation by two crabs, Pachygrapsus marmoratus (Fabricius, 1787) and Lophozozymus incisus (H. Milne Edwards, 1834) (Decapoda: Brachyura: Grapsidae, Xanthidae), on intertidal mussels (Mytiloidea) in the Adriatic Sea
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Sanja Puljas and Brian Morton
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biology ,Xanthidae ,Decapoda ,Grapsidae ,Pachygrapsus marmoratus ,Croatia ,feeding behaviour ,invasive species ,predator-prey relationships ,species displacement ,Lophozozymus incisus ,Intertidal zone ,Zoology ,Aquatic Science ,biology.organism_classification ,Mytiloidea ,Predation - Abstract
We tested the hypothesis that predation on beds of different species of intertidal mussels (Mytiloidea, Mytilidae) by intertidal crabs could influence the abundance and population structure of the pray, changing dominance between the mytilid species over space and time. We tested the influence of selective-feeding behaviours by two Mediterranean intertidal crabs, Pachygrapsus marmoratus (Fabricius, 1787) (Grapsidae) and Lophozozymus incisus (H. Milne Edwards, 1834) (Xanthidae), on populations of the mussels Mytilus galloprovincialis Lamarck, 1819 and Mytilaster minimus (Poli, 1795). Two experiments were conducted, one involving the replacement of consumed prey individuals of different shell lengths by conspecifics of the same size, and a second where no such replacement was made. The predatory pressures were tracked through the preferences for the two species as prey, their selective behaviours in relation to prey sizes, and the type of attack behaviours used. Results demonstrated that the competition for space between the two mytilids is more influenced by the feeding behaviour of L. incisus, which showed a preference for Mytilaster minimus. Comparable data obtained for P. marmoratus suggests that the two resident crabs are not in competition for the same resources. The feeding strategy adopted by L. incisus on Mytilaster minimus showed predation on all of the size classes of Mytilaster minimus because their stronger chelae allow them to mechanically handle larger prey. Lophozozymous incisus uses a simple crushing attack, as opposed to overcoming larger prey using a larger variety of methods, which includes marginal breaking, mandibular biting around valve edges, or a combination of these.
- Published
- 2019
7. The biology and functional morphology of the high-energy beach dwelling Paphies elongata (Bivalvia: Mactroidea: Mesodesmatidae). Convergence with the surf clams (Donax: Tellinoidea: Donacidae)
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Brian Morton
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0106 biological sciences ,Detritus ,biology ,Ecology ,010604 marine biology & hydrobiology ,Mesodesmatidae ,Paphies ,Siphon (mollusc) ,Bivalvia ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Oceanography ,Donacidae ,Bay ,Ecology, Evolution, Behavior and Systematics ,Swash - Abstract
The biology and functional morphology of the Australian endemic Paphies elongata (shell length
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- 2016
8. Changes in the distributions of juvenile horseshoe crabs (Arthropoda: Chelicerata) (2002–2014) related to environmental perturbations at Pak Nai and Ha Pak Nai, Deep Bay, Hong Kong SAR, China
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Christine N.W. Lee and Brian Morton
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0106 biological sciences ,China ,Population Dynamics ,Population ,Aquatic Science ,Oceanography ,010603 evolutionary biology ,01 natural sciences ,Horseshoe Crabs ,Animals ,Humans ,Juvenile ,education ,Ecosystem ,Tachypleus tridentatus ,education.field_of_study ,biology ,Ecology ,010604 marine biology & hydrobiology ,biology.organism_classification ,Pollution ,Horseshoe crab ,Population decline ,Bays ,Habitat ,Hong Kong ,Chelicerata ,Bay ,Environmental Monitoring - Abstract
A survey of juvenile Asian horseshoe crabs in 2002 on the mudflats along Hong Kong's north-western shoreline abutting Deep Bay identified two species, Tachypleus tridentatus and Carcinoscorpius rotundicauda, and assessed their population characteristics. Since the 2002 survey, there have been significant habitat changes to this natal site for the two species. By employing the same, but expanded, sampling protocol, a further survey was, therefore, conducted twelve years later in 2014. A general population decline was recorded for T. tridentatus whereas for C. rotundicauda there was an increase and its distribution had become more widespread. The distribution patterns of the two species were also shown to have changed. The potential factors that might be responsible for recorded changes in the species' population characteristics between 2002 and 2014 are related to anthropogenic perturbations, including environmental habitat alterations notably the building of a bridge linking Hong Kong to Shenzhen in China.
- Published
- 2016
9. Functional morphology ofCardiomya cleryana(d'Orbigny, 1842) (Bivalvia: Anomalodesmata: Cuspidariidae) from Brazilian waters: new insights into the lifestyle of carnivorous bivalves
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Brian Morton, Flávio Dias Passos, and Fabrizio Marcondes Machado
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0106 biological sciences ,biology ,Ecology ,010604 marine biology & hydrobiology ,Functional morphology ,Aquatic Science ,Bivalvia ,biology.organism_classification ,Cuspidariidae ,010603 evolutionary biology ,01 natural sciences ,D orbigny - Abstract
Of the more than 800 Recent species of Anomalodesmata only 16 have been studied alive. The Septibranchia, comprising a number of carnivorous bivalve superfamilies, are no exception to this generalization and, until recently, no living member of this group has been studied since the 1980s. Collected from the shallow, shelf seabed off Brazil,Cardiomya cleryanais one of only a few species to have its morphology described in recent years and the first ever anomalodesmatan to be filmed alive. Important anatomical features such as a greatly extensible foot to secure itself in the sediment with a single byssal thread, exhalant siphon inter-tentacular projections and micro-papillae on the surface of the siphonal tentacles are described. Observations on the species’ behaviour have revealed a lifestyle hitherto not recorded for any septibranch, indeed any anomalodesmatan. The anchoring mechanism ofC. cleryanausing an extraordinarily long byssal thread is described for the first time. The life position ofC. cleryanais at 45° to the sediment-water interface whereas other cuspidariids have been considered to orient themselves vertically. An anatomical comparison betweenCardiomyaandBathyneaerahas revealed close affinities. This study thus provides new insights into the morphology and behaviour of the Cuspidariidae.
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- 2016
10. The organs of prey capture and digestion in the miniature predatory bivalveSpheniopsis brasiliensis(Anomalodesmata: Cuspidarioidea: Spheniopsidae) expose a novel life-history trait
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Flávio Dias Passos, Fabrizio Marcondes Machado, and Brian Morton
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0106 biological sciences ,biology ,010604 marine biology & hydrobiology ,Prey capture ,Anatomy ,Siphon (mollusc) ,Bivalvia ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Life history theory ,Predation ,Raptorial ,Digestion ,Predator ,Ecology, Evolution, Behavior and Systematics - Abstract
Spheniopsis brasiliensis, from depths of 17–148 m off the southern Atlantic coast of Brazil, is a predator of epipsammic micro-crustaceans which it sucks into the infra-septal chamber using a raptorial inhalant siphon and internally generated hydrostatic suction forces. Prey items, which include ostracods, are thought to be pushed into the funnel-shaped mouth using the foot. The stomach is capacious with a short style sac conjoined briefly with the mid gut and possessing a stubby crystalline style. Internal stomach architecture is simplified, with no identifiable sorting areas (unlike other cuspidarioids) and lined virtually completely by a gastric shield. The exoskeletal remains of digested prey are held in the posterior end of the stomach and not in a specialised waste storage pouch as in the con-familial Grippina coronata. The mid gut, hind gut and rectum are all extremely narrow and, thus, only the smallest of faeces can be accommodated and transmitted for anal discharge. Spheniopsis brasilien...
- Published
- 2016
11. Functional morphology, biology and sexual strategy of the circumboreal, adventitious crypt-building,Crenella decussata(Bivalvia: Mytiloidea: Crenellidae)
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Brian Morton, Grete E. Dinesen, and Kurt W. Ockelmann
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0106 biological sciences ,Larva ,biology ,Offspring ,010604 marine biology & hydrobiology ,Ontogeny ,Crypt ,Anatomy ,Aquatic Science ,Bivalvia ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Sex pheromone ,Juvenile ,Mantle (mollusc) - Abstract
The anatomy ofCrenella decussata(Mytiloidea) is described. Individuals of this circumboreal species occupy granular crypts composed of sand grains held in place by mucus. The swollen basal region of the tubule is occupied by an individual, which connects to the sediment surface by two posterior tubes accommodating the inhalant and exhalant streams. There is reduction in musculature and, most importantly, anterior foreshortening of the outer ctenidial demibranchs and loss of the labial palps. This creates an anterior space in the mantle for the initial brooding of fertilized ova by females to the prodissoconch stage. Subsequently, these larvae are transferred to the exhalant tube of the crypt wherein they attach by a single fine byssal thread and are further brooded until the crawl-away juvenile stage is attained. Experimental studies of larval behaviour suggest that parental pheromones sustain the female/offspring bond. Newly hatched individuals responded to parental exhalant water by actively attaching themselves using a byssal thread. This response persisted for 28 days, but not after 55 days when, we suggest, the pheromonal response ceases and offspring are developed sufficiently to take up life in their own nests. Offspring retrieved from parental crypts and fed continuously reached an average shell length of 500 μm after 7.5 months. Brooded offspring thus appear to rely on embryonal energy resources until post-metamorphosis, after which suspension feeding becomes essential for further growth and development before the parental crypt is vacated.
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- 2015
12. A morphological and genetic comparison of Septifer bilocularis, Mytilisepta virgata and Brachidontes variabilis (Bivalvia: Mytiloidea) from Hong Kong and erection of the Mytiliseptiferinae sub-fam. nov
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Priscilla T.Y. Leung, Gabriel Y. Lee, Brian Morton, and Jiehong Wei
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Septate ,Subfamily ,Ecology ,biology ,Brachidontes variabilis ,Intertidal zone ,Zoology ,Aquatic Science ,Bivalvia ,biology.organism_classification ,Mytilisepta virgata ,Animal Science and Zoology ,Adductor muscles ,Ecology, Evolution, Behavior and Systematics ,Mytiloidea - Abstract
This is a comparative study of two extant, umbonally septate, marine, Mytiloidea — the Indo-West Pacific coral associated Septifer bilocularis and the rocky intertidal Mytilisepta virgata with the non-septate, also intertidal, Brachidontes variabilis. Mytilisepta virgata has most recently been associated genetically with the Brachidontinae and this study examines the anatomical and genetic case for this. The three species share many mytiloid characteristics including an heteromyarian shell form that equips them for life within crevices and a radially and bifurcatingly ribbed, or lirate, shell. Only the two septiferines possess an interior umbonal septum in each valve with an anterior adductor muscle located between them. And only the septiferines possess an accessory posterior adductor muscle. It is concluded that S. bilocularis should be retained within the Septiferinae, as currently accepted, whereas M. virgata, though genetically (but not morphologically) linked with representatives of the Brachidontinae, should be included in its own new subfamily – the Mytiliseptiferinae – herein proposed. It thus appears that the two septate mytilids have evolved separately from a common ancestor but, today, share ancestral features of a radially and bifurcatingly ribbed, septate shell and the possession of accessory posterior adductor muscles. How the septum of M. virgata has been formed is described.
- Published
- 2020
13. Mass spawning by the date mussel Lithophaga lithophaga
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Marija Despalatović, Brian Morton, Ivan Cvitković, Ante Žuljević, and Boris Antolić
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0106 biological sciences ,Lithophaga lithophaga ,Shallow sea ,Periodicity ,Science ,media_common.quotation_subject ,Lithophaga lithophaga, mass spawning ,Biology ,010603 evolutionary biology ,01 natural sciences ,Article ,Sexual Behavior, Animal ,Mediterranean sea ,Mediterranean Sea ,Water Movements ,Animals ,Moon ,Full moon ,media_common ,Multidisciplinary ,Reproduction ,010604 marine biology & hydrobiology ,Northern Hemisphere ,Mussel ,biology.organism_classification ,Oceanography ,Period (geology) ,Medicine ,Mytilidae - Abstract
Lithophaga lithophaga is one of the commonest bivalves in the Mediterranean Sea and is present in almost every subtidal calcareous rock. Its reproductive cycle is known only from laboratory studies. Herein, we present data on the species reproductive activities based on localised but mass synchronized spawning events. The species reproduces at the end of the northern hemisphere summer and the majority of significant spawning events occur during the period between full moon and its last quarter. Calm seas are an important pre-requisite for the development of such co-ordinated mass spawning events. ‘Gamete to gamete’ induction seems to be the most likely proximate cue in synchronising gamete release. Spawning begins with a few individuals but spreads progressively along the coastline. In observed situations, reproductive waves finally affect between 10 and >400 m of coastline from 0 to 10 m depth and last longer than three days. In the reproductive zone, dense gamete clouds reduce visibility to zero over tens of metres along the shallow sea bed. No spawning events of such dimensions have been reported upon before for any bivalve.
- Published
- 2018
14. The biology and functional morphology of Mytilaster minimus (Bivalvia: Mytiloidea: Mytilidae) from the intertidal dinaric karst of Croatia (Adriatic Sea)
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Sanja Puljas and Brian Morton
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0106 biological sciences ,Mediterranean climate ,biology ,Ecology ,010604 marine biology & hydrobiology ,heteromyarian form ,shell deformities ,musculature ,statocysts ,evolution ,Mytilaster minimus ,Intertidal zone ,Aquatic Science ,Bivalvia ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Habitat ,Mytilidae ,Brachidontes pharaonis ,Threatened species - Abstract
Mytilaster minimusis widely distributed along the rocky intertidal of much of the Mediterranean's coastline and the Adriatic Sea. Populations are, however, threatened by the Lessepsian invaderBrachidontes pharaonisthat occupies the same habitat and is more tolerant of environmental extremes. This is the first study of the anatomy ofM. minimusin relation to its evolution and adaptations towards an intertidal life on the karsted limestone shores that characterize much of the Mediterranean. In most anatomical respectsM. minimusis a typical mytilid but is small (M. galloprovincialis. A pair of statocysts has been identified in the visceral mass. Most interest, however, resides in the fact the posterior byssal retractor muscles, like the shell, are foreshortened to comprise one paired block and the posterior pedal retractor muscles are situated beneath these not anterior to them as in other mytilids. These adaptations equipM. minimusfor a compressed, squat, life in the intertidal karst. In addition to competition from the introducedB. pharaonisin the Mediterranean,M. minimusis facing competitive exclusion from the nativeMytilus galloprovincialisthat, as a result of intensive and increasing mariculture, is coming to dominate Croatian shorelines. This study is, therefore, prescient in laying the foundations for future research on what is becoming a threatened native Mediterranean species.
- Published
- 2018
15. The biology and functional morphology of the predatory septibranch Cardiomya costellata (Deshayes, 1833) (Bivalvia: Anomalodesmata: Cuspidariidae) from the Acores: survival at the edge
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Brian Morton
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0106 biological sciences ,biology ,Ecology ,Range (biology) ,010604 marine biology & hydrobiology ,Zoology ,Context (language use) ,Aquatic Science ,Siphon (mollusc) ,Bivalvia ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Predation ,Taxon ,Hermaphrodite ,Predator - Abstract
This is the first comprehensive anatomical study of a representative of the septibranch Cuspidariidae. Particular interest in Cardiomya costellata is related to the fact that only two species of such predatory septibranchs have been recorded from the remote Açorean Archipelago and, here, individuals of both taxa are half the shell length of conspecifics throughout the species’ North-eastern Atlantic range. The shell of C. costellata is thin, fragile and rostrate. This latter attribute allows the inhalant siphon (as in other cuspidarioids) to be extended towards potential prey to effect their capture. How this extension is effected has been described but, herein, the hydrodynamic forces needed to achieve this are put into a firmer anatomical context. Uniquely amongst the Anomalesmata, cuspidarioids have, previously, been regarded as dioecious. This is not the case for C. costellata, which is a protandric consecutive hermaphrodite. The gonads and reproductive strategy of this species are compared with those of the spheniopsid Grippina coronata that is representative of a second cuspidarioid family of deeper water predators and which is a simultaneous hermaphrodite brooding self-fertilized embryos in the gonadial follicles with their release being post mortem. Some evidence suggests that in the Açores, the possible crustacean prey of C. costellata are also smaller than their mainland conspecifics, which, when viewed in the overall context of the predator's biology and anatomy, might explain its poor success in the oligotrophic waters of these mid-Atlantic islands.
- Published
- 2015
16. Evolution and adaptive radiation in the Mytiloidea (Bivalvia): clues from the pericardial–posterior byssal retractor musculature complex
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Brian Morton
- Subjects
biology ,Modiolarca ,Modiolinae ,Anatomy ,biology.organism_classification ,Bivalvia ,Retractor ,medicine.anatomical_structure ,Adaptive radiation ,Genetics ,medicine ,Pericardium ,Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics ,Mytiloidea ,Lithophaginae - Abstract
Mytiloidea can be divided into four anatomical categories based upon the relationship between the location of the pericardium and the positions and arrangements of the posterior byssal retractor muscle units. In Category 1, the pericardium is situated above multiple posterior byssal retractor muscle blocks and is typical of the Modiolinae only. This subfamily contains among the oldest mytiloid fossils and is considered to represent the earliest condition. In Category 2, the pericardium is situated anterior to a reduced number, between one (Lithophaga, Botula, Adula and Brachidontes) and six (Mytilus) posterior byssal retractor muscle units. This category is typified by the Mytilinae and related subfamilies, for example, the Botulinae, Adulinae, Lithophaginae and Septiferinae. In Category 3, the pericardium is situated between either two (Limnoperna, Bathymodiolus, Trichomusculus) or one and numerous (Modiolarca) posterior byssal retractor muscle blocks. This category is typical of the Musculinae, Arcuatul...
- Published
- 2015
17. The Biology and Functional Morphology of the Placental Embryo-BroodingNeolepton salmoneum, a Comparison withNeolepton subtrigonum(Bivalvia: Cyamioidea: Neoleptonidae), and a Discussion of Affinities
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Brian Morton
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biology ,Neolepton ,Hinge teeth ,Marine larval ecology ,Heterodont ,Embryo ,Anatomy ,Aquatic Science ,Mantle (mollusc) ,Bivalvia ,biology.organism_classification ,Neoteny ,Ecology, Evolution, Behavior and Systematics - Abstract
The anatomies of two species of Neoleptonidae are described. Clearly heterodont with cardinal and lateral hinge teeth, the shell also has an internal, parivincular ligament. Shell form suggests a shallow burrowing mode of life in coarse gravels in coastal waters. The labial palps are small and the intestine short further suggesting deposit feeding in well-sorted gravels. A pronounced prodissoconch (II) with a marginal ridge argues for lecithotrophic development further facilitating re-colonization of a narrow niche. In most anatomical respects, the two species are simplified with conjoined inhalant and pedal apertures and few posterior sensory mantle papillae. The ctenidia comprise subequal demibranchs with the outer reduced and the inner modified for internally fertilized embryo brooding. The attachment of each embryo chord to the demibranch filaments is probably from secretions produced by basal glands developed on their abrofrontal surfaces. There may also be secondary external pallial broodi...
- Published
- 2015
18. The feeding strategy of the predatoryGyrineum natator(Gastropoda: Neotaenioglossa: Ranellidae) in the Cape d’Aguilar Marine Reserve, Hong Kong, with a review of sulphuric acid use in prey access by the Tonnoidea and experimentally derived estimates of consumption
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Brian Morton
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Oyster ,biology ,fungi ,Marine reserve ,food and beverages ,Zoology ,biology.organism_classification ,Predation ,Fishery ,Ranellidae ,Nassariidae ,biology.animal ,Cape ,Gastropoda ,Seawater ,Ecology, Evolution, Behavior and Systematics - Abstract
Under conditions of otherwise enforced starvation in filtered seawater and with only oysters (Saccostrea mordax) to feed on, an individual of Gyrineum natator consumed > 98%, on average, of its body weight of oyster tissues each week (> 14% per day). When other potential food, such as sediment, organic debris and other newly settled sessile organisms, was available to a similar-sized conspecific living in conditions of unfiltered seawater (in addition to oysters), the oysters only accounted for 1.52% of its average weekly diet (0.21% per day). This was because of the 12 proffered oysters, only four were consumed in contrast to the 12 eaten by the individual in filtered seawater. All the oysters were accessed through large holes made in their shells. It is generally understood that the salivary glands of confamilial ranellids produce secretions of sulphuric acid from greatly enlarged salivary glands and this is demonstrated herein for G. natator also. It is believed that it was these secretions that made t...
- Published
- 2014
19. Growth and Longevity of the 'Living fossil'Congeria kusceri(Bivalvia: Dreissenidae) from the Subterranean Dinaric Karst of Croatia
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Nives Štambuk Giljanović, Melita Peharda, Sanja Puljas, Brian Morton, and Ivana Jurić
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geography ,geography.geographical_feature_category ,biology ,Ecology ,media_common.quotation_subject ,Longevity ,Dreissenidae ,Bivalvia ,biology.organism_classification ,Karst ,Calcium uptake ,Colonisation ,Animal Science and Zoology ,Living fossil ,Ecology, Evolution, Behavior and Systematics ,media_common ,Congeria kusceri - Abstract
The present study analyzed growth and longevity of the endemic cave dwelling bivalve Congeria kusceri obtained from the pit Jama u Predolcu, Croatia. A water temperature of 13–14°C constituted the lower limit for shell growth of C. kusceri. Obtained data also indicated that enhanced calcium uptake by C. kusceri during its summer growth and reproductive phases coincided with a decrease in alkalinity of the pit water. An analysis of shell growth rings in C. kusceri has identified an impressive longevity of 53 years. Calculations of growth rate suggested maximum theoretical shell lengths (L∞) of 16.7 mm for males and 18.7 mm for females and a growth constant of 0.04 year-1 for both sexes. Congeria kusceri can, however, grow to a shell length of > 24 mm, suggesting that longevity of this species could be greater than that identified in this study. The obtained results add to our understanding of how colonisation and continued and successful occupation of a subterranean freshwater habitat has been ach...
- Published
- 2014
20. Review of the functional morphology, biology and perturbation impacts on the boreal, habitat-forming horse musselModiolus modiolus(Bivalvia: Mytilidae: Modiolinae)
- Author
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Brian Morton and Grete E. Dinesen
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biology ,Ecology ,Fauna ,Seta ,Mussel ,Aquatic Science ,Oceanography ,Bivalvia ,biology.organism_classification ,Mytilidae ,Habitat ,Juvenile ,Modiolus modiolus ,Ecology, Evolution, Behavior and Systematics - Abstract
The boreal bivalve Modiolus modiolus is common subtidally where it aggregates to form extensive, long-lived, biogenic habitats with a diverse associated flora and, especially, fauna. Despite this ecological importance, M. modiolus has not been described in terms of its functional morphology and overall biology. Modiolus modiolus is a typical epibenthic, suspension-feeding mytilid, albeit with anatomical modifications adapting it to a partially buried, gregarious lifestyle in a stable environment experiencing medium–high energy levels. The juvenile shell is covered partly in byssal setae secreted by the byssal gland and foot complex and becomes covered in sand grains held in place by a mucoid cement secreted by the dorsal mantle. The camouflaged shell at this vulnerable time probably serves as an anti-predator device. Individuals grow to maximum shell lengths of ∼60–213 mm, depending on depth and locality. With age (≥ 20–45 years), shells often become deformed, particularly posteriorly and around t...
- Published
- 2014
21. The biology and functional morphology of Coralliophaga lithophagella (Bivalvia: Arcticoidea: Trapezidae): An abyssate, deep-water, nestler from the Açores. With comparative notes on the estuarine Trapezium liratum from Hong Kong
- Author
-
Brian Morton
- Subjects
Basalt ,biology ,Ecology ,Arcticidae ,Aquatic Science ,Oceanography ,Bivalvia ,biology.organism_classification ,Paleontology ,Productivity (ecology) ,Algae ,Adaptive radiation ,Mantle (mollusc) ,Arctica islandica ,Geology - Abstract
Coralliophaga lithophagella is a nestler of basaltic rocks in the deeper waters (∼57–360 m) of the Acores and of shallower limestone karst in the Mediterranean where it predominately occurs in empty lithophagine burrows. In the Acores, because of low oceanic productivity and the basaltic, un-boreable, substratum, C. lithophagella is but 50% the shell length of continental European conspecifics and the shell's postero-dorsal margin is growth elevated to enhance particle capture. This is also achieved with relatively enormous ctenidia, minute labial palps and a simplified intestine. Unusually amongst the Trapezidae, C. lithophagella is abyssate and the foot is reduced. Also atypically, and during ontogeny, the shell enlarges postero-dorsally to facilitate particle capture. Anatomical features of the representatives of the constituent genera of the Trapezidae are compared one with another and with Arctica islandica (Arcticidae), the constituent families of the Arcticoidea. It is concluded that the Trapezidae constitutes a discrete clade of epibenthic nestlers, possibly descended from an endobenthic arcticoid ancestor, and showing a trend towards a reduction in shell and hinge complexity. The status of Fluviolanatus subtorta with mantle margins filled with single-celled algae and putatively assigned to the Trapezidae, awaits molecular confirmation.
- Published
- 2014
22. The biology and functional morphology of Septifer bilocularis and Mytilisepta virgata (Bivalvia: Mytiloidea) from corals and the exposed rocky shores, respectively, of Hong Kong
- Author
-
Brian Morton
- Subjects
0106 biological sciences ,Subfamily ,010504 meteorology & atmospheric sciences ,Ecology ,biology ,010604 marine biology & hydrobiology ,Aperture (mollusc) ,Zoology ,Aquatic Science ,Bivalvia ,biology.organism_classification ,01 natural sciences ,Rocky shore ,Type species ,Mytilidae ,Apex (mollusc) ,Animal Science and Zoology ,Adductor muscles ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences - Abstract
There are fossil Mytiloidea assigned to the Septiferinae such as Coxesia mezzalirai and species of Admytilus and Assytilus. Extant species of the Septiferinae are assigned to Septifer and Mytilisepta and date from the end of the Triassic, >200 mya, and the end of the Cretaceous, >65 mya, respectively. All septiferines possess shells characterised by an external radially bifurcate ribbing and internal umbonal septa associated with which is the anterior adductor muscle. The Indo-West Pacific Septifer bilocularis and Mytilisepta virgata are described herein. Uniquely, both possess accessory posterior adductor muscles and posterior pedal retractor muscles that are either absent (M. virgata) or virtually so (S. bilocularis). It is hypothesised that the former muscles have evolved from modified pallial retractors. Gene sequencing evidence suggests that M. virgata is related to the Brachidontiinae and ongoing research further suggests that S. bilocularis is more related to the Mytilinae. This implies parallel evolution and argues that species of Septifer can be retained within the Septiferinae, as currently defined, whereas M. virgata, as the type species, should possibly be placed in its own subfamily – the Mytiliseptiferinae – and, again possibly, allied with the Brachidontiinae. But with both subfamilies retained within the Mytilidae. Uniquely too for the species-diverse marine Mytiloidea, M. virgata possesses ectopic pallial eyes located at the apex of papillae that line the inhalant aperture to the mantle cavity.
- Published
- 2019
23. Species richness, relative abundance and dwarfism in Azorean bivalves: consequences of latitude, isolation or productivity? Or all three?
- Author
-
Brian Morton, António M. de Frias Martins, and Regina Tristão da Cunha
- Subjects
education.field_of_study ,biology ,Foster's rule ,Ecology ,Insular biogeography ,Venerupis decussata ,Population ,Aquatic Science ,biology.organism_classification ,Bergmann's rule ,Productivity (ecology) ,Species richness ,education ,Relative species abundance - Abstract
The Azorean seabed is depauperate in terms of bivalve species richness, there being only between ~70 and 80 recorded to date, most being sub-tidal and generally lacking of specialists. Analysis of large numbers (>3200) of Azorean bivalve shells has revealed that, overall, each species is only ~50% the shell length size of Mediterranean conspecifics. Thus, although Azorean bivalve size may be a consequence of decreasing latitude (Bergmann's Rule), the islands are located at approximately the same latitude as the Mediterranean (and are influenced by those waters) where larger conspecifics occur. Hence, the main reason for bivalve dwarfism in the archipelago appears to result from low oceanic productivity (Foster's Rule). This, in turn, is associated with low diversity, possibly resulting from past extinctions and isolation, and low population sizes, except forErvilia castanea, which here overwhelmingly occupies higher-energy inshore habitats and associated higher productivities. Nevertheless, this species too is dwarfed by mainland conspecifics. Similarly, the introducedVenerupis decussata, found solely within the lagoonal environment of Fajã de Santo Cristo on São Jorge, is somewhat smaller than its mainland conspecifics, although it is abundant enough to warrant artisanal exploitation. This study therefore, supports Foster's Rule and argues for the role of nutrient deficiency in regulating Azorean species richness and individual maximum size. In waters of locally higher productivities, however, population densities increase, but not size.
- Published
- 2013
24. A cadaver unearthed: the anatomy of the Japanese living fossilStirpulina ramosa(Bivalvia: Anomalodesmata: Clavagellidae) - the unique specimen in the collections of Emperor Shōwa
- Author
-
Brian Morton
- Subjects
biology ,Periostracum ,Anatomy ,Bivalvia ,biology.organism_classification ,Burrow ,Cretaceous ,Clavagellidae ,Paleontology ,Adaptive radiation ,Animal Science and Zoology ,Mantle (mollusc) ,Living fossil ,Ecology, Evolution, Behavior and Systematics - Abstract
The only extant, preserved and complete specimen of Stirpulina ramosa has been discovered in the collections of the late Emperor Shōwa (Hirohito) and is described herein. Hitherto, only shells and the adventitious tubes of this species have been described. This study of the anatomy complements previous ones and adds further information as to how the adventitious tube is formed: that is, by the laying down of an organic, periostracum-like, template that is then biomineralized internally to form the tube and is externally plastered with the clasts that constitute the enclosing burrow wall. Such secretions are produced by pallial lobes that unite on the right side to create the characteristic sutured pleat in this region of the tube. The periostracum enclosing the so-interred animal is then secreted against the internal template of the tube. The shell of S. ramosa and, as a consequence, the musculature, is greatly disfigured as a result of the incorporation of the left valve into the fabric of the adventitious tube. This valve can, however, continue to grow within the tube, especially posteriorly. The right valve remains free inside the tube but grows only a little more anteriorly. The anterior mantle, with a minute pedal gape, is greatly thickened and secretes the watering pot component of the tube. In many anatomical respects, for example simultaneous hermaphroditism, S. ramosa still reflects the basic anomalodesmatan plan and such modifications as there are from the clavagellid form relate principally to the structure, formation and thus functioning of the adventitious tube. This study of S. ramosa has allowed the full spectrum of clavagellid adaptive radiation to be analysed and an evolutionary picture created which suggests that species of Clavagella/Dacosta and Stirpulina are Mesozoic (Late Cretaceous) remnants. Conversely, species of Bryopa and Dianadema are more modern, Late Oligocene and Palaeocene (Cenozoic), respectively, and possibly evolved in association with the emergence of the Indo-West Pacific centre of coral diversity, with a postulated average age of just 30 Myr. © 2013 The Linnean Society of London
- Published
- 2013
25. The ectopic compound ommatidium-like pallial eyes of three species of Mediterranean (Adriatic Sea) Glycymeris (Bivalvia: Arcoida). Decreasing visual acuity with increasing depth?
- Author
-
Sanja Puljas and Brian Morton
- Subjects
0106 biological sciences ,Mediterranean climate ,Glycymeris ,Visual acuity ,biology ,010604 marine biology & hydrobiology ,Glycymeris bimaculata ,predator detection ,seston detection ,size reduction with depth ,Pectinoidea ,Cell Biology ,Interspecific competition ,Bivalvia ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Paleontology ,Ommatidium ,medicine ,Animal Science and Zoology ,medicine.symptom ,Ecology, Evolution, Behavior and Systematics - Abstract
The undescribed ommatidium-like ectopic pallial eyes of three Mediterranean species of Glycymeris have been studied and compared with those of the eastern Atlantic G. glycymeris. Wide interspecific variation in eye size between the taxa is recorded with those of G. bimaculata being the largest, G. nummaria the smallest and G. pilosa and G. glycymeris of intermediate and similar dimensions. Such differences result primarily from interspecific variations in the numbers and sizes of the ommatidium-like rhabdomes. The consequences of this will be the differences in abilities to create a summed image and thereby reduce visual acuity. Other bivalves, such as the Pectinoidea, have shown eye size differences in relation to depth. Glycymeris bimaculata, with the largest eyes, occupies the shallowest depths; G. nummaria bears the smallest eyes and occupies the deepest depths. The genetically sister clusters of G. pilosa and G. glycymeris occupy intermediate depths. Accurate depth records for the four taxa blur this hypothesised trend, but comparative eye dimensions suggest it to be valid.
- Published
- 2016
26. Life-history strategy, with ctenidial and pallial larval brooding, of the troglodytic ‘living fossil’Congeria kusceri(Bivalvia: Dreissenidae) from the subterranean Dinaric Alpine karst of Croatia
- Author
-
Brian Morton and Sanja Puljas
- Subjects
biology ,Ecology ,Marine larval ecology ,fungi ,Mytilopsis ,Dreissenidae ,Bivalvia ,biology.organism_classification ,Living fossil ,Dreissena ,Ecology, Evolution, Behavior and Systematics ,Brood ,Internal fertilization - Abstract
Among freshwater bivalves, the brooding of embryos and larvae within the maternal ctenidia is well known. Exceptions to this generalization are the non-brooding freshwater and estuarine species of Dreissena and Mytilopsis, respectively. It was reported that the freshwater troglodytic cousin, Congeria kusceri Bole, 1962, of these dreissenids does not brood either. It is herein demonstrated that C. kusceri undergoes one reproductive cycle each year. Sexes are separate, with an early male and later female bias. A small percentage (2.14%) of individuals is hermaphroditic. The gonads mature over summer from May to November. Spawning commences in September, when females release mature oocytes into their ctenidia and inhale sperm from mature males. Here the oocytes are fertilized, and develop within interfilamentary marsupia. Ctenidial tissues glandularize, and may provide a source of maternal nutrition for the embryos. At the late prodissoconch-1 or prodissoconch-2 stage (PR2, ~220 μm), larvae are released into the infrabranchial chamber via a birth channel along the outer edge of the ventral marginal food groove of both inner demibranchs. Here, they are brooded further in mantle pouches located beneath the inhalant siphon. Subsequently, after the PR2 stage (nepioconch/dissoconch), they are released from the inhalant siphon and assume an independent life as crawling juveniles. Such juveniles may be found amongst clusters of adults. Not only is C. kusceri unique amongst the Dreissenidae in possessing the capacity to brood internally fertilized ova, but it is also exceptional amongst the Bivalvia in possessing the described methods of brooding and birth. Explanations for both lie in its troglodytic lifestyle, decadal length longevity and habitat: that of byssal attachment to the hard surfaces of underground freshwater rivers, caves, pits, and sinkholes in the Tethyan arc of the Dinaric karst. Internal fertilization of a few large yolky eggs, lecithotrophic larvae, ctenidial brooding, and secondary pallial parental care represent relatively recent, Late Miocene, evolutionary adaptations from a Tethyan lentic ancestor.
- Published
- 2012
27. Foregut anatomy and predation byCharonia lampas(Gastropoda: Prosobranchia: Neotaenioglossa) attackingOphidiaster ophidianus(Asteroidea: Ophidiasteridae) in the Açores, with a review of triton feeding behaviour
- Author
-
Brian Morton
- Subjects
Charonia ,biology ,Ecology ,Proboscis ,Prosobranchia ,Gastropoda ,Foregut ,Anatomy ,biology.organism_classification ,Charonia lampas ,Ecology, Evolution, Behavior and Systematics ,Ophidiasteridae ,Predation - Abstract
This paper is the first to describe, in detail, the process of feeding by a species of Charonia. As Charonia lampas commenced attacking its sea star prey, Ophidiaster ophidianus, the latter autotomized its trailing arm and escaped. The pursuing C. lampas ate this arm. The results of this study are not in accord with the established view of feeding by species of Charonia. Firstly, C. lampas did not inject either a venom into its prey to paralyse it nor an acid to access it and, second, nor did it pierce the skeleton of its prey and suck out the tissues, all as reported in the literature. Rather, in the case herein described, C. lampas held and manipulated its prey with the foot and used its taenioglossan radula located at the end of the extendible pleurembolic proboscis to scrape and ingest the soft tissues of the sea star and, subsequently, consume the remaining skeletal components again using the proboscis and contained radula. These two phases of consumption were followed by two matching phases of faece...
- Published
- 2012
28. A significant and unappreciated intertidal mytiloidean genus: the biology and functional morphology ofBrachidontes puniceus(Bivalvia: Mytilidae) from the Cape Verde Islands
- Author
-
Brian Morton
- Subjects
geography ,geography.geographical_feature_category ,biology ,Ecology ,Intertidal zone ,Aquatic Science ,biology.organism_classification ,Bivalvia ,Mytilus ,Cape verde ,Mytilidae ,Hinge teeth ,parasitic diseases ,Archipelago ,Brachidontes ,Ecology, Evolution, Behavior and Systematics - Abstract
Brachidontes puniceus (Gmelin 1791) occurs on all the islands of the Cape Verde Archipelago and along the West African coast from Mauritania to Ghana. The species is morphologically, in terms of its acutely heteromyarian form, strong byssal attachment, stout ligament, thickened shell ornamented with obliquely radial ribs, marginal denticles and strongly developed hinge teeth, intimately adapted to life in the tropical rocky intertidal. Internally, B. puniceus has large ctenidia and tiny labial palps that enhance suspension feeding in, generally, nutrient-deficient tropical waters. As with its congeners distributed throughout the tropics and subtropics globally, B. puniceus is probably also physiologically and reproductively opportunistic such that it can readily colonise hard intertidal substrata. In comparison with boreal mytilids, notably species of Mytilus, the widely successful, abundant and diverse tropical species of Brachidontes remain poorly studied and understood, anatomically and physiologically...
- Published
- 2012
29. The functional morphology of the abyssalLimopsis cristata(Arcoida: Limopsidae) with a discussion on the evolution of the more advanced bivalve foot
- Author
-
Brian Morton
- Subjects
Abyssal zone ,Intoxicative inhalant ,Paleontology ,biology ,Functional morphology ,Selective advantage ,Animal Science and Zoology ,Cell Biology ,Anatomy ,biology.organism_classification ,Deep sea ,Limopsidae ,Ecology, Evolution, Behavior and Systematics - Abstract
The bivalve Limopsis cristata pursues a semi-endobenthic life in abyssal soft sediments. It attaches to particles by up to three byssal threads and filter feeds by inhaling water from posterior and anterior directions. Because of partial burial, however, only the latter is functionally significant. Complex ciliary currents in the mantle cavity concerned with the rejection of unwanted particles keep most material out of the simplified intestine. It is generally considered that the ligament is the constraining force in arcoid evolution. This may be true in part, but the lack of pallial fusions and the retention of anterior and posterior inhalant flows are more powerful limits to radiation in the Arcoida. In the deep sea, the Limopsidae has radiated into many micro-niches through micro-morphological adaptations. Loss of the arcoid ‘heel’ has resulted in the union of the separate rejectory currents of the visceral mass and foot, creating a single discharge point in more advanced bivalves. This greatly simplifies the rejectory roles of the visceral mass and foot and is thus of functional and selective advantage.
- Published
- 2012
30. Functional morphology of Rocellaria dubia (Bivalvia: Gastrochaenidae) with new interpretations of crypt formation and adventitious tube construction, and a discussion of evolution within the family
- Author
-
Mirela Petrić, Brian Morton, and Melita Peharda
- Subjects
0106 biological sciences ,Glycymeris ,biology ,Ecology ,010604 marine biology & hydrobiology ,Zoology ,biology.organism_classification ,Bivalvia ,010603 evolutionary biology ,01 natural sciences ,Gastrochaenidae ,14. Life underwater ,Ostrea edulis ,Mantle (mollusc) ,Bivalve shell ,Mollusca ,Ecology, Evolution, Behavior and Systematics ,Pinna nobilis - Abstract
Rocellaria dubia bores into subtidal rocks of karsted limestone in the Adriatic Sea and elsewhere. It also bores into the shells of various bivalve species. The mechanism of boring has hitherto been debated, but examination of occupied shells suggest that this is achieved by mechanical (the shell) abrasion and chemical etching using secretions produced from glands in the anterior mantle. Fast growing bivalves such as Ostrea edulis and Pinna nobilis carry heavy R. dubia burdens and encapsulate the borer in secreted calluses. Slow growing bivalves such as the burrowing Venus verrucosa and Glycymeris violacescens carry low R. dubia burdens, are less able to encapsulate the borers and probability incur enhanced mortalities as a result. Individuals of R. dubia removed from their limestone boreholes re-secreted adventitious tubes around their siphons, probably from glands in the posterior mantle. The lifestyle of R. dubia is now better understood and its ability to bore bivalve shells in particular suggests how the more advanced tropical gastrochaenids Cucurbitula and Eufistulana have evolved from initial (as juveniles) bivalve shell borers into occupants of adventitious crypts and tubes, respectively. It is further argued that the Gastrochaenidae show convergent similarities with the similar crypt and tube building representatives of the Clavagelloidea
- Published
- 2011
31. Predator–prey-scavenging interactions betweenNucella lapillus,Carcinus maenasandEulalia viridisall exploitingMytilus galloprovincialison a rocky shore recovering from tributyl-tin (TBT) pollution
- Author
-
Brian Morton
- Subjects
education.field_of_study ,biology ,Population ,biology.organism_classification ,Semibalanus balanoides ,Mytilus ,Predation ,Eulalia viridis ,Fishery ,Rocky shore ,Carcinus maenas ,education ,Ecology, Evolution, Behavior and Systematics ,Nucella - Abstract
In 2004, a study began on a small (25 individuals) population of Nucella lapillus on the south coast of England. Following the global ban of tributyl-tin in the same year, freed from “imposex”, the size of the population increased such that by August 2010 it comprised > 1240 individuals. On the groyne, N. lapillus fed on barnacles (Semibalanus balanoides) up to a mean shell height of 14 mm, i.e. the first year of life. Thereafter, N. lapillus fed principally on Mytilus galloprovincialis by shell drilling. When the numbers of N. lapillus had risen significantly, a relationship with Carcinus maenas was detected, the latter feeding on M. galloprovincialis, by mandibular chipping in summer, but also consuming the remains of N. lapillus meals in winter. Further, the polychaete Eulalia viridis scavenged the remains of N. lapillus meals, both barnacles and mussels. This is the first time such feeding interactions have been identified.
- Published
- 2011
32. The biology and functional morphology of Arctica islandica (Bivalvia: Arcticidae) – A gerontophilic living fossil
- Author
-
Brian Morton
- Subjects
geography ,geography.geographical_feature_category ,biology ,Continental shelf ,Ecology ,media_common.quotation_subject ,Heterodont ,Longevity ,Arcticidae ,Aquatic Science ,Oceanography ,Bivalvia ,biology.organism_classification ,Negligible senescence ,Arctica islandica ,Living fossil ,Ecology, Evolution, Behavior and Systematics ,media_common - Abstract
The North Atlantic bivalve Arctica islandica is a fishery resource and as such there is considerable information about it related to growth, physiology and reproduction. In contrast, however, its form, functional morphology and lifestyle have received scant attention. This study describes the anatomy of A. islandica and provides information to match fossil and rRNA evidence that it is a living fossil probably associated with a Cretaceous heterodont mactrid group adapted to deposit feeding. Arctica islandica lives in buried motionless repose feeding on the carbon-rich seabed surface micro-layer of northern boreal continental shelves. This study concludes that the indolent lifestyle exhibited by A. islandica, along with tissue antioxidant levels sustained into gerontocy, predisposes it to negligible senescence. As a consequence, and as has been demonstrated elsewhere, A. islandica can live for centuries – the current longevity record being 405 years obtained through an analysis of shell growth ring...
- Published
- 2011
33. The composition and spatial distribution of scavenging hyperbenthos in the Cape d'Aguilar Marine Reserve, Hong Kong
- Author
-
Christine N.W. Lee and Brian Morton
- Subjects
Leptostraca ,Amphipoda ,Oceanography ,biology ,Ecology ,Fauna ,Gammaridea ,Marine reserve ,Melitidae ,Nebalia ,Aquatic Science ,biology.organism_classification ,Bay - Abstract
Baited traps with a 5 mm diameter opening were deployed 9 cm off the seabed in the Cape d'Aguilar Marine Reserve, Hong Kong. In contrast to analogous studies from boreal waters, lysianassoids accounted for 0.5% of the total number of trapped hyperbenthos. Species of Tisbe (Copepoda: Tisbidae), Ceradocus (Gammaridea: Melitidae), Nebalia (Leptostraca: Nebaliacea), unidentified benthic ostracods, Neanthes cricognatha (Polychaeta: Nereidae) and a species of Lepidepecreum (Amphipoda: Lysianassoidea) were caught in a decreasing order of numerical importance. A spatial segregation of trapped fauna was identified between the reserve's shallow Lobster Bay (Ceradocus sp. monopolized the trapped fauna in the former area, while the other species were caught almost exclusively from the latter. Insignificant Ceradocus sp. catch differences between baited and control traps suggested that they functioned only as ‘habitat traps’ for this species. Almost all other organisms attracted to the bait were hyperbenthic scavengers. Their absence from the shallows might be due to the coarser and lower organic contents of the sediments, also related to faster flow rates here. Finally, we confirm that in subtropical Hong Kong, lysianassid amphipods are not as significant hyperbenthic scavengers as they are in boreal waters.
- Published
- 2011
34. The biology and functional morphology of Modiolarca subpicta (Bivalvia: Mytilidae: Musculinae), epizoically symbiotic with Ascidiella aspersa (Urochordata: Ascidiacea), from the Kattegat, northern Jutland, Denmark
- Author
-
Brian Morton and Grete E. Dinesen
- Subjects
Rocky shore ,biology ,Mytilidae ,Ecology ,Ascidiella aspersa ,Aquatic Science ,Siphon (mollusc) ,Urochordata ,biology.organism_classification ,Bivalvia ,Mollusca ,Ascidiacea - Abstract
This study of the little known north-eastern Atlantic mytilid Modiolarca subpicta suggests a more intimate relationship with ascidians and, especially, Ascidiella aspersa, than has hitherto been appreciated. Both live for ~18 months and the reproductive cycle of both is approximately co-ordinated so that juvenile ascidians become available as hosts to the settling spat of the symbiotically epizoic M. subpicta each summer. Settling spat of M. subpicta are thought to be attracted to the exhalant flow from the ascidian's anal siphon. After the ascidian's death, the liberated mussels may adopt a wandering, free-living, lifestyle they have occasionally been reported to pursue. Anatomically, M. subpicta is of the typical mytilid plan, albeit simplified commensurate upon its normal lifestyle of protective envelopment within the host's tunic. The foot, however, is highly mobile and in addition to being used for locomotion, especially in juveniles, is responsible for the planting of byssal threads, typically dorsally above the shell, so that each individual stimulates the ascidian to produce an epidermal pocket into which it manœuvres itself and reposes, securely attached, but dorsal side down Modiolarca subpicta, epizoic in the tests of ascidians, could have evolved from a more isomyarian, equivalve, ancestor via a nestling, epibyssate, Trichomusculus-like shaped intermediary with ventral flattening and, hence, stability characteristic of the more familiar heteromyarian mytilids of rocky shores and lotic freshwaters being achieved through living dorsal side down.
- Published
- 2010
35. Form and functional morphology of Raetellops pulchella (Bivalvia: Mactridae): an example of convergent evolution with anomalodesmatans
- Author
-
Brian Morton
- Subjects
Mactridae ,Pseudofeces ,Body plan ,Buttress ,biology ,Convergent evolution ,Animal Science and Zoology ,Anatomy ,Adductor muscles ,Bivalvia ,biology.organism_classification ,Mantle (mollusc) - Abstract
The bivalve Raetellops pulchella is a highly specialized, deposit-feeding member of the Mactridae. Studies of its form and function provide an example of how the bivalve body plan can be modified to facilitate the exploitation of mud as a food resource, and help in understanding how this lifestyle has evolved. Adaptations to this lifestyle include an overall reduction in ctenidial size and loss of the descending lamellae of both outer demibranchs. This reduction is associated with the enlargement of the labial palps to process inhaled sediment. In the mantle cavity, a waste canal below the posterior mantle flaps facilitates pseudofeces removal. The midgut is long and capacious, presumably to cope with the large amounts of ingested organic material. In addition, individuals of R. pulchella have unusually thin, brittle, and rostrate shells, with narrow siphonal gapes. They possess a shell buttress in each valve extending from the hinge plate to above the posterior adductor muscle. This buttress functions to prevent the brittle shell valves from fracturing when adduction occurs. A buttress is also seen in some representatives of the Anomalodesmata; in particular, the situation in R. pulchella is most like that seen in individuals of the similarly deposit-feeding species Offadesma angasi (Anomalodesmata: Periplomatidae). I interpret the similar shell form of these deposit-feeding clams as an example of convergent evolution.
- Published
- 2010
36. Predator–prey interactions between a population of Nucella lapillus (Gastropoda: Muricidae) recovering from imposex and Mytilus galloprovincialis (Bivalvia: Mytilidae) on the south-east coast of England
- Author
-
Brian Morton
- Subjects
Imposex ,education.field_of_study ,biology ,Kleptoparasitism ,Muricidae ,Population size ,Population ,Aquatic Science ,Bivalvia ,biology.organism_classification ,Predation ,Fishery ,education ,Nucella - Abstract
Over a 52-month period beginning in May 2004 and concluding in August/September 2008, and coinciding with the period over which tributyltin was banned as a ship anti-foulant globally, a population of the dogwhelk, Nucella lapillus on the south-eastern coast of England, was studied for changes in population size and structure, reproduction and feeding behaviour. During the study period, the size of the N. lapillus population grew from ~25 individuals to >500, i.e. a 20-fold increase, and recovery from imposex was total. Significant changes in feeding behaviour were also reported. For example, peaks in N. lapillus predation were recorded over the winter months, but as population size increased, this temporal seasonality was masked due to the growing numbers of juveniles feeding on smaller and smaller individuals of Mytilus galloprovincialis (as opposed to barnacles) as the study progressed. Similarly, with freedom from imposex, the numbers of failed drilling attempts declined and numbers of prey with more than one drill hole increased as the incidence of kleptoparasitism increased. Predated M. galloprovincialis were also increasingly attacked in the antero- and postero-dorsal quadrants of their shells as the study progressed. Contrary to expectations, only a slightly positive relationship between predator and prey sizes was recorded overall however, suggesting that beyond a shell height of ~13 mm, when the transition from barnacle to mussel feeding occurs, M. galloprovincialis individuals of virtually any size are preyed upon by N. lapillus.
- Published
- 2009
37. The watering pot shellDianadema minima(Bivalvia, Anomalodesmata, Clavagellidae): re-description and an interpretation of adventitious crypt formation
- Author
-
Brian Morton
- Subjects
Maxima and minima ,Paleontology ,biology ,Coral ,Adaptive radiation ,Convergent evolution ,Botany ,Crypt ,Animal Science and Zoology ,Bivalvia ,biology.organism_classification ,Mantle (mollusc) ,Clavagellidae - Abstract
Two small cemented, cryptic, species of Dianadema (Bivalvia: Anomalodesmata: Clavagellidae) have been recorded from shallow waters of the Indian Ocean. These are Dianadema minima and Dianadema mascarensis. A study of their shells and adventitious crypt morphologies, however, suggests that the two species are conspecific, the former name taking precedence. This re-description of D. minima suggests that on settlement, the larva develops a juvenile shell that continues to grow until a length of ∼9.0 mm is reached, when it secretes around itself a primary calcareous crypt and cements itself ventrally into a concavity in coral rubble. Subsequently, a crown of tubules is secreted from the dorsal surface of the exposed mantle and an adventitious siphonal tube is formed, which is characteristically oriented at ∼45° from the horizontal. In the absence of preserved internal tissues and pre-adult life history stages, there is no possibility of fully comprehending exactly how such a remarkable adventitious structure is produced. Dianadema minima does, however, provide us with another example of the remarkable adaptive radiation of the Clavagelloidea and, in particular, the pattern of convergent evolution expressed not just between D. minima (Clavagellidae) and Humphreyia strangei (Penicillidae), but also between the two families that have independently evolved “watering pot” shells and tubes.
- Published
- 2009
38. A New Genus and Species of Barnacle (Cirripedia, Pedunculata) Commensal with Arca Navicularis Bruguière, 1789 (Mollusca, Bivalvia, Arcoidea) from Queensland, Australia, with an Analysis of the Relationship
- Author
-
Brian Morton and Diana S. Jones
- Subjects
Arca navicularis ,biology ,Ecology ,Zoology ,Animal Science and Zoology ,Aquatic Science ,Bivalvia ,biology.organism_classification ,Mollusca - Abstract
[A previously undescribed heteralepadomorph genus and species is recorded as attached to the inside of the shell of the living epibenthic bivalve Arca navicularis, dredged from the waters of Moreton Bay, Queensland. The combination of anatomical features exhibited by the barnacle match some of the characteristics of Malacolepas. However, several characters are distinctive and a new genus and species is, therefore, proposed and named Arcalepas brucei sp. nov. Occurring in groups of up to ten individuals inside each host, Arcalepas brucei sp. nov. clearly benefits from the protection afforded by inhabiting the living bivalve and the flow of oxygenated water created by Arca navicularis. However, the barnacle also exploits the ciliary rejection currents of its host and appears to collect the pseudofaeces the bivalve removes from its mantle cavity along the rejectory tracts that internally occupy each ventral mantle margin. It does this by expanding its cirral net into the rejectory tracts and plucking up the unwanted particles collected by the suspension feeding activities of the bivalve. The barnacle's relationship with its host is thus best described as commensal. This is the first record of such an association from Australian waters. Eine bisher unbeschriebene Gattung und Art einer heteralepadomorphen Seepocke wird hier von der Schaleninnenseite einer lebenden epibenthischen Muschel (Arca navicularis) von Moreton Bay, Queensland (Australien) beschrieben. Die Kombination einiger anatomischer Merkmale dieser Seepocke stimmt mit Besonderheiten von Malacolepas uberein. Allerdings besitzt die neue Art charakteristische Merkmale, die die Beschreibung einer neuen Gattung rechtfertigen. In Gruppen bis zu zehn Individuen besiedelt Arcalepas brucei gen. und sp. nov. ihren Wirt, in dem sie nicht nur Schutz findet, sondern auch vom Strom sauerstoffreichen Wassers profitiert, der von Arca navicularis erzeugt wird. Die Seepocke nutzt die dem Abtransport des Abfalls dienenden Wimperstrome des Wirtes, indem sie ihnen Pseudofaeces entnimmt, die die Muschel aus der Mantelhohle entlang von Wimperbahnen entfernt, die innen auf den ventralen Mantelrandern verlaufen. In diese Wimperbahnen halt die Seepocke ihre Zirren und bedient sich an dem von der Muschel verschmahten Material, das wahrend ihrer Nahrungsaufnahme ausgesondert wird. Die Beziehung zwischen Seepocke und Muschel ist daher am besten als kommensal zu bezeichnen und ist bis jetzt die einzige Beziehung dieser Art, die von australischen Gewassern bekannt ist., A previously undescribed heteralepadomorph genus and species is recorded as attached to the inside of the shell of the living epibenthic bivalve Arca navicularis, dredged from the waters of Moreton Bay, Queensland. The combination of anatomical features exhibited by the barnacle match some of the characteristics of Malacolepas. However, several characters are distinctive and a new genus and species is, therefore, proposed and named Arcalepas brucei sp. nov. Occurring in groups of up to ten individuals inside each host, Arcalepas brucei sp. nov. clearly benefits from the protection afforded by inhabiting the living bivalve and the flow of oxygenated water created by Arca navicularis. However, the barnacle also exploits the ciliary rejection currents of its host and appears to collect the pseudofaeces the bivalve removes from its mantle cavity along the rejectory tracts that internally occupy each ventral mantle margin. It does this by expanding its cirral net into the rejectory tracts and plucking up the unwanted particles collected by the suspension feeding activities of the bivalve. The barnacle's relationship with its host is thus best described as commensal. This is the first record of such an association from Australian waters. Eine bisher unbeschriebene Gattung und Art einer heteralepadomorphen Seepocke wird hier von der Schaleninnenseite einer lebenden epibenthischen Muschel (Arca navicularis) von Moreton Bay, Queensland (Australien) beschrieben. Die Kombination einiger anatomischer Merkmale dieser Seepocke stimmt mit Besonderheiten von Malacolepas uberein. Allerdings besitzt die neue Art charakteristische Merkmale, die die Beschreibung einer neuen Gattung rechtfertigen. In Gruppen bis zu zehn Individuen besiedelt Arcalepas brucei gen. und sp. nov. ihren Wirt, in dem sie nicht nur Schutz findet, sondern auch vom Strom sauerstoffreichen Wassers profitiert, der von Arca navicularis erzeugt wird. Die Seepocke nutzt die dem Abtransport des Abfalls dienenden Wimperstrome des Wirtes, indem sie ihnen Pseudofaeces entnimmt, die die Muschel aus der Mantelhohle entlang von Wimperbahnen entfernt, die innen auf den ventralen Mantelrandern verlaufen. In diese Wimperbahnen halt die Seepocke ihre Zirren und bedient sich an dem von der Muschel verschmahten Material, das wahrend ihrer Nahrungsaufnahme ausgesondert wird. Die Beziehung zwischen Seepocke und Muschel ist daher am besten als kommensal zu bezeichnen und ist bis jetzt die einzige Beziehung dieser Art, die von australischen Gewassern bekannt ist.]
- Published
- 2009
39. The Evolution of Eyes in the Bivalvia: New Insights*
- Author
-
Brian Morton
- Subjects
genetic structures ,biology ,Laternulidae ,Pectinoidea ,Anatomy ,Aquatic Science ,biology.organism_classification ,Bivalvia ,Ostreoidea ,Anomioidea ,sense organs ,Mantle (mollusc) ,Ecology, Evolution, Behavior and Systematics ,Mytiloidea ,Pterioidea - Abstract
Two types of multi-cellular eyes have been identified in the Bivalvia. Paired cephalic eyes occurring internally above the anterior end of the ctenidia are seen only in representatives of the Arcoidea, Limopsoidea, Mytiloidea, Anomioidea, Ostreoidea, and Limoidea. These eyes, comprising a pit of photo-sensory cells and a simple lens, are thought to represent the earliest method of photoreception. Many shallow-water marine, estuarine, and freshwater bivalves also possess simple photoreceptive cells in the mantle that enable them to respond to shadows. In some other marine, shallow-water taxa, however, a second type of more complex photoreceptors has evolved. These comprise ectopic pallial eyes that can be divided into three broad categories, in terms of their locations on the (i) outer mantle fold in representatives of the Arcoidea, Limopsoidea, Pterioidea, and Anomioidea, (ii) middle fold in the Pectinoidea and Limoidea, and (iii) inner fold in the Cardioidea, Tridacnoidea, and Laternulidae (Ano...
- Published
- 2008
40. Seasonal variations in the density of and corallivory by Drupella rugosa and Cronia margariticola (Caenogastropoda: Muricidae) from the coastal waters of Hong Kong: ‘plagues’ or ‘aggregations’?
- Author
-
Brian Morton and Graham Blackmore
- Subjects
Platygyra ,biology ,Ecology ,Coral ,Rugosa ,Porites ,Acropora ,Drupella ,Aquatic Science ,biology.organism_classification ,Montipora ,Favia - Abstract
Sixteen coral sites in the coastal waters of Hong Kong were examined for the corallivorous muricid gastropods Drupella rugosa and Cronia margariticola. These were recorded from all sites where there was significant hard coral cover and observed feeding upon species of Platygyra, Leptastrea, Stylocoeniella, Porites, Favites, Cyphastrea, Goniastrea, Favia, Acropora, Montipora, Pavona, Lithophyllon, Hydnophora, Echinophyllia and Plesiastrea. One large aggregation (~2000 individuals) of, mainly, D. rugosa was observed but much smaller groups (D. rugosa were not significantly different and, usually, ~2 individuals · m2 were recorded. Seasonal differences were, however, significant with numbers greater during the summer, possibly related to reproduction. Feeding activity followed a similar pattern and was also largely confined to summer.Prey selection by Drupella rugosa was complex in the field and changed according to the relative abundance of each coral taxon. Acropora was strongly selected for at all sites where it was present and Montipora, Platygyra and Pavona were usually fed upon in greater proportions than their abundances. Leptastrea, Cyphastrea, Favites, Favia and Goniastrea were fed upon but in proportions lower than suggested by their abundances. Goniopora was never fed upon despite being relatively common. The seasonality of feeding, low density, rarity of large feeding aggregations, prey selection and aspects of the feeding behaviour, that is, generally only consuming the coral's coenenchyme (the polyps surviving), suggest that while D. rugosa is widespread in Hong Kong, and contrary to other views, it poses little, if any, threat to local coral communities. Thus, reported feeding clusters of D. rugosa are probably not ‘plague’ outbreaks but examples of seasonally fostered ‘aggregations’ of feeding (and probably reproducing) individuals. Indeed, no ‘plague-like’ outbreak of any species of Drupella has been reported upon in the literature since 1999.
- Published
- 2008
41. Predation uponMytilus galloprovincialis(Mollusca: Bivalvia: Mytilidae) by juvenileCarcinus maenas(Crustacea: Decapoda) using mandibular chipping
- Author
-
Elizabeth M. Harper and Brian Morton
- Subjects
biology ,Mytilidae ,Ecology ,Decapoda ,Juvenile ,Durophagy ,Carapace ,Carcinus maenas ,Aquatic Science ,Bivalvia ,biology.organism_classification ,Crustacean - Abstract
Field observations of small (Mytulus galloprovincialisat Littlehampton (West Sussex) on the south-eastern coast of England showed that many collected as recently dead shells had a distinctive pattern of damage around the posterior valve margins. Laboratory experiments confirmed that smallCarcinus maenas (C. maenasfed successfully on a range of mussel sizes (5–20 mm shell length), positively correlated with carapace width. All used the same technique to access the bivalve prey, that is, by marginal mandibular chipping in order to achieve sufficient damage to allow insertion of a chelal dactyl between the valves. Mandibular chipping has previously been reported upon from non-chelate decapods and juvenile lobsters. The chelae of juvenileC. maenasare small and have a lower mechanical advantage than has been reported upon for adult conspecifics which, in any case, are not highly adapted for durophagy. We suggest that because of the poor mechanical performance and small gape of the chelae juvenileC. maenasbehave as though they were achelate. As well as broadening our understanding of the repertoire of known feeding behaviours ofC. maenas, our study may also provide an insight into the evolution of durophagy within the Decapoda.
- Published
- 2008
42. Barnacles (Crustacea: Cirripedia) from Conic Island Cave, Hong Kong
- Author
-
Diana S. Jones and Brian Morton
- Subjects
Ecological niche ,geography ,Paleontology ,Barnacle ,geography.geographical_feature_category ,South china ,Cave ,biology ,Ecology ,biology.organism_classification ,Crustacean ,Tetraclitella pilsbryi ,Ecology, Evolution, Behavior and Systematics - Abstract
Two species of barnacles (Cirripedia) have been collected from Conic Island Cave, Hong Kong, at depths of between −11.8 and −18.2 m C.D. These are Armatobalanus quadrivittatus (Darwin) and Tetraclitella pilsbryi (Utinomi). Neither is a cave endemic. Armatobalanus quadrivittatus ranges widely throughout the Indo‐West Pacific and T. pilsbryi is restricted to the Sino‐Japanese region (the East and South China Seas and waters of southern Japan) although both are typical of hypobiotic niches. Armatobalanus quadrivittatus has not hitherto been recorded from Hong Kong and its occurrence here brings the local total of barnacle species to 60.
- Published
- 2008
43. Soft corals, sea fans, gorgonians (Octocorallia: Alcyonacea) and black and wire corals (Ceriantipatharia: Antipatharia) from submarine caves in Hong Kong with a checklist of local species and a description of a new species ofParaminabea
- Author
-
Katherine Lam and Brian Morton
- Subjects
geography ,geography.geographical_feature_category ,food.ingredient ,Octocorallia ,Ecology ,Marine habitats ,Submarine ,Biology ,biology.organism_classification ,Black coral ,Ceriantipatharia ,Oceanography ,food ,Cave ,Alcyonacea ,Paraminabea ,Ecology, Evolution, Behavior and Systematics - Abstract
Twenty species of soft corals belonging to the Octocorallia and one species of Ceriantipatharia were collected from two submarine caves in the oceanic southeastern waters of Hong Kong. Of these, 13 octocorals and one black coral were new records for Hong Kong. One new species, Paraminabea hongkongensis sp. nov., is described herein. Sixty octocorals and six ceriantipatharians have now been recorded from Hong Kong, most from open areas of the seabed. That the 14 new records for Hong Kong are from small marine caves highlights the importance of such marine habitats locally. None of the 14 species is a cave endemic, however, all have been recorded from elsewhere in the Indo‐West Pacific. Nevertheless, it is recommended that Hong Kong's submarine caves be designated as Sites of Special Scientific Interest and possibly further receive protection under the Marine Parks Ordinance (1995).
- Published
- 2008
44. Shell‐bearing Mollusca (Bivalvia and Gastropoda) from submarine caves in Hong Kong
- Author
-
Brian Morton, Katherine Lam, and Kmy Leung
- Subjects
geography ,geography.geographical_feature_category ,Ecology ,Fauna ,Hiatella ,Biology ,biology.organism_classification ,Bivalvia ,Archaeology ,Spondylus ,Cave ,Gastropoda ,Mollusca ,Epitonium ,Ecology, Evolution, Behavior and Systematics - Abstract
In October 2002, the Hong Kong Marine Caves Expedition was convened jointly by the Swire Institute of Marine Science, The University of Hong Kong and the Natural History Museum, London. The expedition explored the marine cave habitats of Hong Kong and their fauna. This paper describes the diversity of marine cave molluscs collected using SCUBA from two marine caves at Conic Island and Steep Island in the eastern waters of Hong Kong. Twenty, and eight species of shell‐bearing epifaunal bivalves and gastropods, respectively, were collected from the ceilings and walls of the two caves. Another 11 infaunal bivalve species were collected from the sediment‐filled floors of the caves. Of the species identified, eight are new records for Hong Kong. These are the bivalves Spondylus anacanthus, Hiatella cf. orientalis, Panomya turgida, Nuculana sp., Abra cf. fujitai, Pinguitellina cf. nux, and Lyonsiella cf. parva, and the epitonid gastropod Epitonium bullatum. The epibenthic molluscs recorded during this survey we...
- Published
- 2008
45. Attack responses of the southern Australian whelk, Lepsiella vinosa (Lamarck, 1822) (Gastropoda: Muricidae), to novel bivalve prey: an experimental approach
- Author
-
Brian Morton
- Subjects
Rocky shore ,Whelk ,Ecology ,biology ,Muricidae ,Gastropoda ,Intertidal zone ,Mytilopsis sallei ,Bivalvia ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Predation - Abstract
In their native ranges, muricid gastropods feed on similar prey, often bivalves and barnacles, which they usually drill. Throughout its wide southern Australian distribution, the intertidal Lepsiella vinosa feeds on a range of prey from barnacles and littorinid gastropods in the southeast to mussels in the southwest. A number of muricids have been introduced throughout the world, either with oysters or in ship ballast water. In their new environments, they switch to native prey but their feeding responses to them have never been studied in the laboratory. The object of this study was to study the feeding of L. vinosa on a suite of non-native species. Australian Lepsiella vinosa was taken to Hong Kong, offered five different possible prey species and allowed to feed to satiation for many weeks. Replacement of consumed prey items by similar-sized conspecifics was undertaken until trends emerged. Lepsiella vinosa readily attacked thick- and thin-shelled bivalves from Hong Kong’s sandy beaches, Anomalocardia squamosa and Caecella chinensis, respectively, and from rocky shores, Septifer virgatus and Hormomya mutabilis, again respectively. It attacked them all, as it does its major prey item, Xenostrobus inconstans, in its native southwestern Australia, by either drilling or marginal probing with its proboscis. It also preferred intermediate sized prey (10–15 mm shell length), as with its natural prey. It quickly attacked the sandy shore species, and Hormomya mutabilis and Mytilopsis sallei, the latter two being closely similar in shell form and size to its natural prey X. inconstans. Hormomya mutabilis was the most favored prey, and was most similar in shell form and thickness to X. inconstans. This study therefore suggests that if introduced elsewhere, L. vinosa could radically affect intertidal community structure.
- Published
- 2008
46. Drilling and chipping patterns of bivalve prey predation by Hexaplex trunculus (Mollusca: Gastropoda: Muricidae)
- Author
-
Elizabeth M. Harper, Brian Morton, and Melita Peharda
- Subjects
0106 biological sciences ,biology ,Modiolus barbatus ,Periostracum ,Muricidae ,010604 marine biology & hydrobiology ,Shell (structure) ,Aquatic Science ,biology.organism_classification ,Bivalvia ,010603 evolutionary biology ,01 natural sciences ,Fishery ,Paleontology ,Whelk ,Gastropoda ,Hexaplex trunculus ,14. Life underwater - Abstract
The predatory caenogastropod Hexaplex trunculus employed different methods to access different species of bivalve prey characterized by different shell thicknesses. Hexaplex trunculus drilled Callista chione and Venus verrucosa at their shell margins but the latter species also laterally. It also attempted to drill two species of Tapes but successfully penetrated these only after chipping the shell margin. Chipping, whereby a labral spine is forcibly pushed between the prey's valves, especially posteriorly, to break them followed by proboscis insertion, was typically applied to access the thinner shelled prey Cerastoderma glaucum whereas Modiolus barbatus and Mytilus galloprovincialis were either chipped or drilled. The pattern of M. galloprovincialis shell penetration appears related to predator and prey size. Small (40 mm shell height) H. trunculus tended to drill rather than marginally chip M. galloprovincialis. Medium sized (55 mm shell height) H. trunculus either chipped or drilled M. galloprovincialis in approximately equal proportions but also at the valve margin. Larger (70 mm shell height) H. trunculus tended to laterally drill average sized (35 mm shell length) and the biggest (65 mm shell length) M. galloprovincialis. When larger M. galloprovincialis are attacked it thus becomes increasingly more difficult for H. trunculus to chip and drill the shell margin, possibly because the periostracum is thicker here in such individuals, and the predator resorts to lateral drilling. This is possible because as the mytilid ages its surface periostracum becomes progressively eroded and thus thinner and easier to access. Scanning electron microscopy (SEM) identified shell microstructure damage which shows that the chipping and drilling behaviours of H. trunculus result from labral spine damage and dissolutional etching, respectively, rather than mechanical radula rasping. These observations have implications for the use of such predation marks to identify the predator taxon implicated from holes in either empty Recent shells or fossil material.
- Published
- 2007
47. Reproductive Output and Seasonality of Limnoperna fortunei
- Author
-
Brian Morton, Cristina Damborenea, Daniel Cataldo, Nancy Correa, Demetrio Boltovskoy, Francisco Sylvester, and Pablo E. Penchaszadeh
- Subjects
Larva ,biology ,Range (biology) ,Reproduction ,fungi ,Zoology ,Golden mussel ,Mussel ,Subtropics ,Seasonality ,Seasonal cycles ,biology.organism_classification ,medicine.disease ,Salinity ,Water column ,medicine ,Ciencias Naturales ,Limnoperna fortunei ,Cohorts - Abstract
Young Limnoperna fortunei mature sexually from 5–6 to ~15 mm. The species is generally dioecious, with approximately equal numbers of males and females and very small (< 0.6 %) proportions of hermaphrodites. The gametogenic cycle has been described for both Asian and South American populations, recognizing between four and five reproductive phases. Gonadal cycles based on histological sections yielded somewhat dissimilar results for different areas. In Hong Kong, two yearly peaks in reproductive output were detected. In South America, mature sperm and ova have been recorded year round and several irregularly spaced spawning events have been observed, as well as more or less continuous breeding punctuated by peaks in spring and at the end of the summer. Reproductive studies based on changes in the abundance of larvae in the water column have been carried out in South America and in Japan. In tropical and subtropical South America, larval output is more or less continuous for 6–10 months of the year, often with a major peak in spring–early summer, and a smaller one in the late summer–autumn. In Japan, at considerably lower water temperatures, larval production is limited to 1–2 months centered around summer. Apparent disagreements between results based on histological data and on larval counts stem from the fact that while the latter integrate the reproductive output of extensive mussel beds dispersed over large areas, histological evidence pinpoints with high precision the ripening and spawning of isolated mussel clusters. Aside from water temperature, several other factors (pH, salinity, dissolved oxygen, suspended solids, chlorophyll a, flood–drought cycles) have been proposed as reproductive triggers, but actual associations have not been demonstrated. Peak larval densities can exceed 20,000 ind./m3, but, normally, values range around 6000 ind./m3, showing major fluctuations within short periods, as well as changes as a function of time elapsed post colonization, and availability of substrata suitable for adult occupation. Microcystin-producing cyanobacterial blooms can kill L. fortunei larvae. Facultad de Ciencias Naturales y Museo
- Published
- 2015
48. The Biology and Anatomy of Limnoperna fortunei, a Significant Freshwater Bioinvader: Blueprints for Success
- Author
-
Brian Morton
- Subjects
Colonisation ,Taxon ,biology ,Habitat ,Range (biology) ,Ecology ,Dreissenidae ,Anatomy ,Limnoperna fortunei ,biology.organism_classification ,Dreissena ,Life history theory - Abstract
Limnoperna fortunei first came to scientific attention when it was introduced into the potable freshwater supply system of Hong Kong around 1968. The initial occurrence in Hong Kong was related to the commencement of supplies of water from the East River in China. Aspects of the biology and anatomy of L. fortunei were investigated in 1973 (Morton, Malacologia 12:265–281, 1973). Then, comparisons were made with other mytiloids and with the invasive Dreissena polymorpha (Dreissenidae), which L. fortunei resembles superficially. The suggestion of a relationship between the two taxa was discounted on anatomical grounds—both species being convergently heteromyarian, adapting them to similar lives in the freshwater habitats of Eastern and, subsequently, Western Europe and North America, and mainland Asia plus Japan and Taiwan and latterly South America, respectively. The present study re-examines aspects of the biology and anatomy of L. fortunei commensurate upon its recent range extensions, specifically with regard to its occupation of a variety of freshwater habitats in order to better understand the reasons for its opportunistic success. It is concluded that L. fortunei probably evolved from a brackish water either Xenostrobus-like or Perna-like ancestor—the question of Limnoperna’s ancestry still unresolved. Regardless, it was the evolution of the heteromyarian form in the, indisputedly mytiloidean, ancestor that opened up the hitherto bivalve-unoccupied hard-surface epibenthic environment for colonisation in both lentic and lotic freshwaters ecosystems. This was probably associated with the adoption of osmoregulation and efficient systems for the collection, selection and digestion of ample seston resources. The energy thereby obtained has been focussed into rapid fecundity at the expense of shell growth and the adoption, thereby, of a r-selected sexual strategy and life history trait.
- Published
- 2015
49. Morphological and mitochondrial-DNA analysis of the Indo-West Pacific rock oysters (Ostreidae: Saccostrea species)
- Author
-
Brian Morton and Katherine Ka Wai Lam
- Subjects
Mitochondrial DNA ,Oyster ,biology ,Ecology ,Interspecific competition ,Aquatic Science ,biology.organism_classification ,Intraspecific competition ,Ostreidae ,Rocky shore ,biology.animal ,Animal Science and Zoology ,Taxonomy (biology) ,Southern Hemisphere - Abstract
Species of Saccostrea are common oysters on Indo-Pacific rocky shores. The taxonomy of this genus is unclear, however, because of morphological plasticity among its constituent species. Oyster samples with distinct morphotypes were collected from shores experiencing different degrees of wave exposure in Japan, Taiwan, China, Vietnam, Singapore and Australia. Intraspecific and interspecific variations in shell characters have been identified. Only S. kegaki could be readily differentiated from S. cucullata-B, S. cucullata-C and S. mordax by multivariate shell allometric analyses. Phylogenetic analyses using partial mitochondrial 16S DNA sequences of approximately 513 base pairs identified two clades that correspond to superspecies, i.e. putative S. cucullata and putative S. mordax, comprising nine and two lineages from the Indo-West Pacific, respectively. These are S. cucullata-A, B, C, D, E, F, G, S. kegaki and S. glomerata in one clade, and S. mordax-A and B in the other. Interspecific sequence divergence (Kimura-2-parameter values) between lineages ranged from 1.02% to 11.74%. Both S. cucullata-C and S. kegaki are restricted to the northern hemisphere, whereas S. glomerata seems to be a temperate species from the southern hemisphere. S. cucullata-D occurs only in Taiwan. Other species, i.e. S. cucullata-A, B, D, E and F and S. mordax-A and B, have a wide range on rocky shores in the tropical and subtropical Western Pacific and in both northern and southern hemispheres.
- Published
- 2006
50. Scavenging behaviour by Ergalatax contractus (Gastropoda: Muricidae) and interactions with Nassarius nodifer (Gastropoda: Nassariidae) in the Cape d'Aguilar Marine Reserve, Hong Kong
- Author
-
Brian Morton
- Subjects
biology ,Muricidae ,Ecology ,Nassariidae ,Gastropoda ,Marine reserve ,Zoology ,Carrion ,Aquatic Science ,biology.organism_classification ,Predator ,Bay ,Predation - Abstract
Aspects of the feeding behaviour of Ergalatax contractus (Muricidae) were studied. Field experiments demonstrated that large numbers of individuals of this species, comprising ∼90% of a suite of gastropod scavengers, were attracted to baited traps in the subtidal sands of Lobster Bay, Cape d'Aguilar Marine Reserve, Hong Kong. Laboratory experiments identified the effective chemo-detection distances of E. contractus as 60 cm in still and >80 cm in flowing water, respectively. The average times to arrival at bait in still and flowing water were 92.3 and 69.0 min, respectively, but were significantly less for individuals experiencing a longer period of starvation. The mean time taken for E. contractus to consume a meal was 70.6 min.Comparisons were made between Ergalatax contractus and Nassarius nodifer, representative of a suite of sympatric scavenging nassariids in Lobster Bay. The nassariid arrived significantly faster at bait in both still (30.2 min) and flowing water (20.8 min) than E. contractus and fed faster (25.7 min), as is typical of representatives of the Nassariidae. Although the two species partition carrion resources temporally, manipulation experiments provided evidence for inter-specific competition between them. That is, although E. contractus possesses the morphological and behavioural characteristics of a predator, its opportunistic scavenging abilities have led to its success and numerical superiority on the shallow subtidal sands of Lobster Bay. The dominance of E. contractus in Lobster Bay, and elsewhere in Hong Kong, is unusual. Here, the normally predatory E. contractus, far outnumbers all other scavengers, possibly because of an enhanced, largely allochthonous, supply of food which it is able to exploit by virtue of its previously identified opportunistic habit of scavenging the leftovers of other predators. The presence of inter-specific competition between E. contractus and a sympatric suite of nassariids enhances, not impedes, carrion exploitation.
- Published
- 2006
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