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Summary Here we describe the results of a preliminary study to evaluate the response of the cellular skeleton of the large African barb, Labeobarbus intermedius, to exposure to high levels of the thyroid hormone T3 for 1 and 3 months. We examined the effects in terms of mineral density and mechanical properties of the operculum bone, as well as evaluated and compared the light microscopy features of this bone between the treatment groups and the untreated control group. We found a significant increase in bone mineral density in the treated groups compared to untreated controls, and a tendency towards a corresponding increase of bone material stiffness (Young's modulus). These findings suggest that thyroid hormone enrichment may contribute to improved skeletal properties in pond-raised fish, and help moderate osteomalacia, a commonly seen problem in aquaculture.

Captive American horseshoe crabs Limulus polyphemus housed at the National Aquarium presented with a variety of shell and gill lesions over a 3 yr period. Carapace lesions were located on both the dorsal and ventral prosoma and opisthosoma and included multifocal circular areas of tan discoloration, ulcerations, and/or pitting lesions, extending from superficial to full thickness. Gill lesions involved both the book gill cover (operculum) and individual book gill leaflets and included multifocal circular areas of tan discoloration, tan to off-white opaque proliferative lesions, and/or areas of black discoloration. Histopathology revealed fungal hyphae, with variable morphology throughout the thickened and irregular cuticle of the carapace and occasionally penetrating into subcuticular tissues, with associated amebocytic inflammation. Book gill leaflets were infiltrated by fungal hyphae and contained necrotic debris and amebocytes. Thirty-eight of 39 animals (97%) evaluated via histopathological examination had intralesional fungal hyphae. Fungal cultures of carapace and gill lesions were attempted in 26 tissue samples from 15 individuals and were positive in 13 samples (50%), with 10 cultures (77%) yielding identification to genus. Fusarium sp. was identified in 8 of the 10 cultures (80%) via culture morphology. The Fusarium solani species complex was confirmed in 6 of these 8 (75%) via polymerase chain reaction amplification of 2 different ribosomal-specific sequences of isolated fungal DNA. Ante-mortem systemic and topical treatments were performed on some affected individuals, but no appreciable change in lesions was observed. Mycotic dermatitis and branchitis are serious health issues for captive American horseshoe crabs.

A single juvenile pomacentrid specimen (5.9 mm standard length) was collected from the Korea Strait in October 2010. The specimen is characterized by punctate-stellate melanophores scattered on the operculum and dorso-ventral region in front of the caudal peduncle, the lack of melanophores on the posterior end of the anal fin base, the presence of 14 spines and 14 soft rays on the dorsal fin, and the presence of 2 spines and 12 soft rays on the anal fin. A molecular analysis based on mitochondrial DNA 16S rRNA sequences showed that this specimen is closely related to adult Chromis mirationis (d = 0.002), but that it differs from Chromis notata (d = 0.017). Juvenile C. mirationis differ from juvenile C. notata in having no melanophores on the posterior end of the anal fin base. We propose a new Korean name, “tti-ja-ri-dom” for C. mirationis.

We tested if variations (i.e., breadth) in morphology and habitat use vary predictably among six aquatic gastropod species that were collected across Indiana and Illinois, USA. We predicted that interspecific morphological variation would positively covary with variation in habitat use among species. We used geometric morphometrics (Procrustes technique and relative warp analysis) to quantify morphology and multivariate analyses (PCA) to quantify habitat. Increased morphological breadth did not vary predictably with increased habitat breadth. However, we found that life history traits correspond with patterns in morphological and habitat breadth for these six aquatic gastropods. Pulmonate gastropods (use lungs for respiration) that lack an operculum cover exhibited decreased morphological breadth compared to coenogastropods (use gills for respiration). This pattern may ultimately be a function of behavioral adaptations in freshwater gastropods. Gastropods that are capable of breathing air or using other behavioral modifications such as burrowing to escape predators may not require high morphological breadth. Conversely, selection may favor higher morphological breadth in gastropods with gills that also do not move out of the water column to escape predators.

The age and growth of Neptunea (Barbitonia) arthritica cumingii sampled from the West Sea of Korea were determined from 1,062 operculums from October 2007 to September 2008. Age of Neptunea (Barbitonia) arthritica cumingii was determined from the rings on the operculum. The relationship between shell height (SH; mm) and shell width (SW; mm) was expressed by the following equation : SW = 0.5757 SH + 0.222 (R = 0.8723), and shell height (SH; mm) and total weight (TW; g) was highly correlated by the equation : TW = 0.0002 SH (R = 0.9121). The main spawning periods was estimated June to July through fatness index analysis. The relationship between shell height and ring radius of operculum in each ring group was expressed as a regression line. Therefore, there is a correspondence in each ring formation. Based on the monthly variations in the marginal index (MI) of the operculum, it is assumed that the ring of this species was formed once a year during the period of July to August. Growth curves for shell height (SH) and total weight (TW) fitted to the von Bertalanffy's equation were expressed as follows :        

This study investigated two potential strategies to survive short and longer-term aerial exposure in a galaxiid. This scaleless fish possesses cutaneous pores that dilated in the short-term (15 min-3 h) but contracted over longer periods (15 h) out of water, suggesting that these organs are used to cope with shorter durations of air exposure. Pores on the abdominal surface showed the greatest variation while those on the operculum surface hardly changed. Conversely, thickening of the epithelial layer of secondary gill lamellae showed a slower increase but persisted in an approximately linear fashion over the duration of this study, indicating that this is a strategy that facilitates longer-term aerial exposure. Thus, this species has the capacity to accommodate both short and long-term exposure to air.

A study was undertaken to assess the prevalence, mean intensity, abundance and seasonality of parasites of fish in a natural, freshwater, tropical lake, southeast Nigeria. A total of 1191 fish specimen belonging to four families ( Cichlidae, Bagridae, Hepsetidae and Channidae ), seven genera and nine species were collected from the lake and examined for parasites. Eleven (11) species of parasites comprising metacercariae of three digenetic trematodes, one cestode, five nematodes and two acanthocephalans were isolated. Clinostomoides sp. showed the highest range of sites of infection, and the operculum carried significantly more worm burden (F = 196.843, d.f. = 5, p = 0.000) than other sites infected by this parasite. Prevalence ranged from 0.7% in Clinostomum tilapiae infection of T. zillii to 71.7% in Neochinorhynchus sp.2 infection of Hepsetidae fasciatus with an overall prevalence of 59.5%. Mean intensity ranged from 1.0 ± 0.0 in Clinostomoides sp. and Proteocephalus sp. infection of P. obscura and Anemone occidentalis , respectively, to 76.5 ± 29.7 in Neoechinorhynchus sp. 2 infection of H. fasciatus. Neoechinorhynchus sp. 2 infection also had the highest mean abundance (54.90 ± 2.74) while the lowest was recorded in the Clinostomoides sp. infection of H. fasciatus . Patterns of infection were significantly different in the prevalence and abundance of Clinostomoides sp; Camallanus sp.3 and Neoechinorhynchus sp.1 while mean intensity was comparable in all cases. Keywords: Natural lake, freshwater, fish parasites, worm burden African Journal of Biotechnology , Vol. 13(3), pp. 502-508, 15 January, 2014

A reassessment of Glaphyrites material from the Late Carboniferous of Uruguay, famous for being the first ammonite described with the complete buccal mass in situ (also referred to Eoasianites earlier), indicates that the structures recorded as opercula or anaptychi, respectively, by earlier authors in several of the Glaphyrites specimens are rather to be interpreted as (1) dislodged fragments of the calcareous shell, originating from the aperture, and isolated by demineralization as well as fragmentation during taphonomy, and (2) remnants of demineralization, the fine lines suggesting that the rims of the ‘opercula’ are elongated “puckers” produced by shrinking of the inner layer of the calcareous shell during dissolution. An energy dispersive X-ray (EDX) analysis corroborated the impression that these fossils consist uniformly of a matrix of calcium phosphate (apatite), containing a less significant amount of iron and sulphur, among other elements. The Glaphyrites material is re-interpreted as possessing a lower and upper jaw with a general beak-like morphology that is comparable to modern nautilids and coleoids, a complex radula, but evidence for an operculum protecting the soft body is missing. Since the jaw elements are located in the anterior portion of the body chamber, but not directly at the aperture, and are furthermore of smaller size compared to the cross section of the aperture, we assume that a double function of jaws as opercula in Glaphyrites is unlikely.

Background: The Chinese mitten crab (Eriocheir sinensis) is an economically important aquatic species in China. The artificial breeding crabs are also increasing in number day by day. However, knowledge about spermatozoal organization of the crab is still very limited. Aims and Objectives: In the present study, the spermatozoal ultrastructure of the E. sinensis is illustrated for improving artificial breeding technique. Materials and Methods: The spermatozoa are observed by light microscopy and transmission electron microscopy. Results: Spermatozoa are located in the lumen of seminiferous tubules. The spermatocytes and spermatids are observed in the wall of seminiferous tubules. The spermatophores are both present in the lumen of vas deferens and seminal vesicles. A mature spermatozoon consists of a central electron dense acrosome and a peripheral electron lucent nucleus within structures-organelles complex. The acrosome is divided into three zones, including inner acrosome zone, outer acrosome zone and zonal texture. The centre of acrosome is the perforatorium within parallel arranged perforatorial tubules along vertical axis. The highest electron dense operculum surrounds the head side of perforatorium. Conclusion: The ultrastructure of spermatozoa of E. sinensis is illustrated. In particular, the outermost part of the acrosome appears as concentric circles and is described as zonal texture.

A new oxyuroid nematode, Ichthyouris nunani n. sp., is described from the intestine of the freshwater benthopelagic characiform fishes Laemolyta taeniata and Curimata acutirostris, both of which were caught in the Tocantins River, State of Maranhao, Brazil. The new species is easily distinguished from all other species of the genus mainly because of the distribution of the male caudal papillae, the morphology of the spicule, and the fact that the eggs have an operculum and many long, thread-like filaments at each pole. This is the first helminth species described in both hosts, and this report contributes to the knowledge of the helminthological fauna of fish in the Neotropical region.

Estimating age and maturity of the commercially harvested queen conch (Strombus gigas) offers fishery managers a unique challenge: How can these variables be determined if only the soft, edible parts of the marine gastropod are landed in port whereas the shells used for aging purposes are discarded at sea? Throughout the greater Caribbean region, including The Bahamas, the age and maturity of S. gigas are estimated by measuring the thickness of the flared lip of the shell. Given the traditional fishery practices for queen conch, including at-sea processing, developing proxy measures for S. gigas age and maturity would greatly benefit fishery managers. To this end, we used traditional morphometric analysis to find a significant inverse relationship between the ratio of operculum length to operculum width and shell lip thickness. A logistic regression model using the same operculum metric and a breakpoint of 15mmfor shell lip thickness as an indication of S. gigas maturity predicted correctly the maturity level for 86% of queen conch sampled in The Bahamas. This study provides the proof of principle for relationships between operculum measures and queen conch age and maturity that can be applied by fishery managers throughout the geographical range of the species.

The intrauterine eggs of the pleurogenid trematode Brandesia turgida ( Brandes, 1888 ), exhibiting advanced stages of miracidial differentiation and fully formed, ciliated miracidia, were examined by means of transmission electron microscopy (TEM). Each embryonated egg is composed of a mature miracidium surrounded by a four-layered egg wall: (1) an outer, anucleate layer external to the eggshell, which forms a thick cocoon; (2) the operculate egg-shell; (3) a small remnant of the compact, granular cytoplasm of the outer embryonic envelope ( sensu stricto ); and (4) a relatively distinct cellular remnant of the inner embryonic envelope. Layers enveloping the egg apparently play an important role in the protection, metabolism and storage of nutritive reserves for the developing miracidium. The outer, anucleate layer, or cocoon, situated externally to the eggshell and composed of a transparent, electron-lucent substance with numerous dense, osmiophilic islands attached to its peripheral membrane, has never previously been seen in TEM studies of the eggs of parasitic platyhelminths. The origin, formation, functional ultrastructure and chemical composition of this peculiar layer remain enigmatic, although its function appears to be protective. The thick, electron-dense eggshell resembles that of other trematodes, exhibiting a characteristic fissure zone around the operculum. The very small, indistinct remnants of the outer embryonic envelope appear in the form of a very thin, compact, granular cytoplasm closely attached to the inner surface of the eggshell. Conversely, the inner embryonic envelope is frequently apparent at one or both poles of the developed egg as a syncytial envelope formed by the fusion of mesomeres. This envelope, even in eggs containing a fully formed miracidium, still has the features of a metabolically active layer with an energy storage capability. Lysosome-like structures observed in some eggs may be involved in the autolysis of the embryonic envelopes.

A new species of harpacticoid copepod, Cletocamptus goenchim sp. nov., was found in the mouth of the Mandovi estuary, Goa, India. This species seems to be the same reported in 1979 from Lake Kolleru (east coast of India) as C. deitersi, but until new specimens are studied, the 1979 record will remain as doubtful. The new species seems to be related to C. stimpsoni. They can be separated by the armature of the mandibular palp, the shape of the outer element of basis of P2, the ornamentation of the posterior margin of cephalothorax, pro-, and urosomites, and anal operculum of both male and female, the armature formula of male P5EXP, the armature formula of the male P2ENP2, and the relative length and shape of the inner apophysis of the male P3ENP2. Some comments on specimens of Cletocamptus from Korea and China are given.

Female response to various aspects of male trait morphology and the effect of female feeding motivation were investigated in the swordtail characin Corynopoma riisei, a species where males are equipped with a flag-like food-mimicking ornament that grows from the operculum. Unfed females responded more strongly to the male ornament and showed a stronger preference for larger ornaments than did fed females. Females were shown not to discriminate between artificial male ornaments of either undamaged or damaged shape.

Two orthothecid hyoliths, Gracilitheca astronauta n. sp. and Nephrotheca sophia n. sp. are described from the “middle” Cambrian Buchava Formation of the Skryje-Týřovice Basin in the Czech Republic. The new forms are based on about thirty well-preserved external and internal moulds of both conchs and opercula. Gracilitheca astronauta n. sp. is classified under the family Gracilithecidae Sysoev, 1972 and may be distinguished by clearly triangular cross-section of the conch, whereas Nephrotheca sophia n. sp. is characterized by transversally elongated cardinal processes reaching the lateral opercular margin and is combined with the family Orthothecidae Sysoev, 1958 emended Malinky, 2009. Several specimens of G. astronauta show operculum preserved inside of the conch. Stratigraphic ranges and geographic distributions within the Skryje-Týřovice Basin are established for both taxa.

The sensory exploitation hypothesis states that pre-existing biases in female sensory systems may generate strong selection on male signals to match such biases. As environmental conditions differ between populations, sexual preferences resulting from natural selection are expected to vary as well. The swordtail characin (Corynopoma riisei) is a species in which males carry a flag-like ornament growing from the operculum that has been proposed to function as a prey mimic to attract females. Here, we investigated if female plasticity in feeding preferences is associated with plasticity in preference for an artificial male ornament in this species. Females were trained for 10 days by offering them differently coloured food items and were then tested for changes in preferences for differently coloured artificial male ornaments according to foraging experience. We found a rapid and pronounced change in female preference for the colouration of the artificial ornament according to food training. Thus our results support the possibility that sensory exploitation may act as a driving force for female preferences for male ornaments in this species.

Morphology and morphometry of six biotypes (B, Q, Cv, ZHJ-1, ZHJ-2 and ZHJ-3) of Bemisia tabaci (Gennadius) from China on cotton plants were studied by using microscopes. Nymphal body sizes and characters were measured and observed, especially on the 4th instar (pupal case), including the vasiform orifice, operculum, lingula, length and thickness of anterior and posterior wax margins, width of thoracic tracheal combs. Adult characters of both sexes were investigated including the body size, compound eyes, antennal segments, vasiform orifice, hind tarsi and genitals. The results indicated that differences of some morphological characters or morphometrics were significant among the six biotypes of B. tabaci in China: (1) Pupal sizes of the exotic biotypes (B and Q) were significantly larger than the indigenous biotypes with the following order as B>Q>ZHJ-1>Cv>ZHJ-3>ZHJ-2; (2) for both male and female adults, sizes of all characters investigated in the invading biotypes (B and Q), especially B, were much larger than those of the indigenous ones.

Clitellate annelids (i.e., oligochaetes including leeches) secrete cocoons as part of their nor- mal reproductive cycle. Typically, the cocoon sheath is passed over the head of the leech and sealed at both ends by opercula (i.e., glue-like material secreted by the clitellum). Both the fibrous cocoon wall (CW) and opercula are chemically-related biomaterials that share unusual physiochemical properties, including thermal and chemical resiliency. To explore the underlying mor- phology of the operculum, we examined cocoons from four leech species (i.e., Myzobdella lugubris, Theromy- zon tessulatum, Erpobdella obscura ,a ndErpobdella punctata) by transmission (TEM) and scanning electron microscopy (SEM). Transmission electron micrographs of all opercula revealed a common, ultrastructural pat- tern comprising an electron-dense mosaic of ordered polygons that surrounded interspersed cavities. The long axes of cavities were often oriented directionally, suggesting that operculum material is pliable prior to solidification and distorted as a consequence of cocoon deposition. Concomitantly, the operculum permeates jagged edges of the cocoon sheath sealing the cocoon, which provides a mechanically strong CW/operculum boundary. SEM of leech opercula revealed globular nanoparticles comparable to that observed in bioadhe- sives from disparate animal phyla (e.g., mussel, barna- cle, sea star), suggesting a convergent mechanism of bioadhesion among animals. J. Morphol. 274:940-946

Macro-ionic composition of fish opercula may be an indicator of the fish stock identity. This is especially interesting in river estuaries, where individual sections of the estuary may differ in terms of their hydrochemical regimes. Diversified macro-ionic tissue composition is likely to provide clues not only about the origin of an individual fish, but also about its possible migration routes. The current study researched this aspect of the chemical composition of perch collected from different sections of the Oder River estuary. A total of 60 European perch, Perca fluviatilis L., were obtained from 3 sampling sites located in the river at Widuchowa, Szczecin Lagoon, and Pomeranian Bay, where waters are subject to dynamic macro-ionic transformations. Fish length ranged from 20 to 25 cm. Opercula of the fish were examined for their content of calcium, magnesium, strontium, sodium, and potassium, with the aid of the flame method using a Perkin-Elmer 3100 atomic absorption spectrophotometer. Perch inhabiting the waters of the Oder River between Widuchowa and Szczecin Lagoon had their opercula composed predominantly of calcium. Calcium was also the predominant ion dissolved in the water in this area; Ca represented 83.6% of all cations in the water and 41.6% of those present in the bones of the perch operculum. The increased levels of salinity near the sea were associated with the replacement of calcium in bones by other, more readily available elements (magnesium or strontium). Differences in the observed macro-ion composition of the opercula were sufficient to assign the perch studied to two distinct groups inhabiting fresh and brackish waters.

The caenogastropod family Littorinidae is almost exclusively marine, but a unique freshwater genus, Cremnoconchus, is known from India. Its members are restricted to montane streams on the western escarpment of the Western Ghats, at altitudes between 300 and 1400 m. Four species and several varieties were described in the 19th century, but no taxonomic study has been carried out for over 120 years and the last anatomical report was in 1935. Nevertheless, they are of unusual evolutionary interest and also of conservation concern as a genus endemic to the Western Ghats biodiversity hotspot. Based on anatomical study of newly collected material and examination of historical and type specimens, we present a systematic revision of Cremnoconchus, illustrating shells, radulae, and reproductive anatomy. The very large eggs, invaginated penial filament, and calcified operculum are unique among Littorinidae. Three valid, described species (C. syhadrensis, C. conicus, C. canaliculatus) are recognized in the northern Western Ghats in Maharashtra state, where all can occasionally be found sympatrically. We describe an additional six new species from the central Western Ghats in a small area (linear distance 80 km) of Karnataka state, over 500 km south of the previously known range of the genus. Here the species each appear to be restricted to a single drainage system. Because of their highly restricted distribution and fragile habitat, this radiation of nine species is judged to be endangered. © 2013 The Linnean Society of London

During an ongoing systematic survey on species diversity of myxozoans parasitising allogynogenetic gibel carp Carassius auratus gibelio (Bloch) in China, plasmodia were detected in the fins, lip, jaw, gill chamber, gill arches, operculum and oral cavity of infected fish. Combining the morphological and molecular data, the present species was identified as Myxobolus turpisrotundus Zhang, Wang, Li et Gong, 2010. Histopathological examination revealed that despite infecting different organs, M. turpisrotundus always occurred in dermis, demonstrating its affinity to this tissue. Histopathological effect of M. turpisrotundus on the host is relatively mild except parasites in the gill arches producing compression of the adipose tissue and heavy adductor muscles deformation with lymphohistiocytic infiltrates. In addition, the plasmodia in different sites were with the same complex structure arrangement: cup-like cells with unknown derivation, a thin collagenous fibril layer, areolar connective tissue, basement membrane and host epithelial cell. Ultrastructural analysis showed that the parasite has monosporic pansporoblast and sporogenesis followed the usual pattern of most of the myxosporeans.

We observed the osteological development of larval and juvenile red spotted grouper (Epinephelus akaara) in order to generate data for the assessment of skeletal deformities and to inform phylogenetic systematics research. Larvae and juveniles were obtained from a aquafarm in Muan-gun, Jeolla-namdo Province, Korea. The average water temperature at the time of breeding was 23.0°C and average water salinity was 33.0 psu. Freshly hatched fish larvae had not undergone any ossification, but ossification of the parasphenoid bone, which forms the base of the cranium, occurred as the juveniles reached an average body length (BL) of 2.49 mm. At the same time, ossification of the preopercle and opercle occurred in the operculum, and ossification of the maxilla, which forms the upper jaw, and the dentary bones, which form the lower jaw, began. In addition, ossification of the vertebra occurred by formation of 7 vertebral centra and the neural spine in the abdominal vertebra. When the juveniles reached an average (BL) of 5.22 mm, ossification of the nasal, lateral ethmoid, and alisphenoid bones occurred in the cranium; ossification of the endopterygoid and metapterygoid bones began in the palatine region; and ossification of the hypohyal and interhyal bones occurred in the hyoid arch. At an average (BL) of 20.9 mm, ossification of the basisphenoid bone in the cranium and the suborbital bone in the orbital region occurred. Ossification of the vertebra then occurred by the formation of long pairs of ribs from the third to the ninth abdominal vertebrae, completing osteological development.

Physoclistous fish are unable to rapidly ascend through the water column without significant risk of barotrauma via swim bladder hyperextension or rupture. Here, we report on the discovery of a highly specialised anatomical structure which permits some physoclistous fish species, the samson fish Seriola hippos and silver trevally Pseudocaranx georgianus, to vent swim bladder gas during ascent. Dissections of injected casts and X-ray imaging revealed the swim bladder ‘vent’ to consist of a membranous opening in the roof of the swim bladder which led to a flattened tube that bifurcated around the vertebral column and exited via a small, oval-shaped hole in the pharyngo-cleithral membrane underneath each operculum. Identification of these distinctive holes revealed that venting had occurred on ascent in 96 % of in S. hippos captured from depth. Decompression from simulated 30 m water depth in an experimental hyperbaric chamber revealed that venting in P. georgianus commenced when predicted swim bladder volume was approximately double that of its initial volume and ceased when the fish were again near neutrally buoyant. A homologous structure was identified in S. lalandi and S. dumerili. This structure represents an important step in the evolution of the teleost swim bladder which circumvents the normal physoclistous restriction on rapid ascents by eliminating, or minimising, barotrauma. Ecological benefits of this ability include an improved ability to capture prey, escape predators and perform ‘spawning rushes’. The increased resilience to barotrauma provided by the swim bladder ‘vent’ may also reduce the levels of post-release discard mortality for deep-water species which possess the structure.

The operculum of terrestrial snails tightly seals the shell aperture providing protection from predators and body-water loss. To allow respiration with a closed operculum, operculate land snails repeatedly evolved shell devices such as tubes or channels that open to the air. In all Asian members of the Alycaeidae, an externally closed tube lies along the suture behind the aperture that possesses a small internal opening into the last whorl at the tube's anterior end. However, this structure presents a paradox: how is gas exchanged through an externally closed tube? Here we show that many microtunnels open into the tube and run beneath radial ribs along the growth line of the last whorl in Alycaeus conformis . These tunnels open to the outside of the shell surface near the umbilicus. Examination under high magnification revealed that the outermost shell layer forms these tunnels only in the whorl range beneath the sutural tube. Each tunnel ( ca 16 µm diameter) is far narrower than any known metazoan parasite. These findings support our hypothesis that the externally closed sutural tube functions with microtunnels as a specialized apparatus for predator-free gas exchange with minimal water loss when the operculum seals the aperture.

Using morphological traits including weight, the genetic group effect in three varieties of Turbinella pyrum was determined. A total of 300 T. pyrum individuals (100 per variety) were used. The morphometric analysis showed that the shell outer lip thickness and operculum width were found to be significantly different in between the three varieties of T. pyrum. The study also showed that the shell length, body whorl length and operculum length significantly differed in between G1 (var. obtusa) and G2 (var. acuta synonymous T. rapa) and shell width differed significantly in between G2 (var. acuta) and G3 (var. globosa). The effect of genetic group on the shell depth and adult animal weight were found to be non-significant. The observed mean length, width and depth in G1 genetic group (var. obtusa) supports its higher market value in comparison to the other two genetic groups studied. This variety has moderate lip thickness, which may be another reason for its higher demand in bangle industry than the other two genetic groups. The G2 (var. acuta) and G3 (var. globosa) genetic groups although comparatively larger, have a disproportionate body size then G1 (var. obtusa). The standardized shell morphological characters in present study are helpful to draw primary guidelines for identification of three T. pyrum varieties studied. The present morphometry data on T. pyrum varieties also plays key role for species description and also for their domestication.

This study described the initial development of Pseudoplatystoma reticulatum, as well as changes in growth patterns. Morphometric and meristic variables were analyzed during embryonic, larval and juvenile periods, even as allometric growth coefficients for larvae and juveniles. Eggs showed an average diameter of 1.79 mm and broad perivitelline space (23.41%). The total length (TL) of the larvae ranged from 3.05 to 25.72 mm, and the total number of myomeres ranged from 45 to 50 (preanal = 13-16 and postanal = 30-35). Initial pigmentation is poor, concentrated at the extremities of the yolk sac. In the flexion stage, the pigmentation intensifies and forms a longitudinal stripe extending from the snout to the operculum and two longitudinal stripes on the body, one dorsal and the other ventral, that unite at the caudal peduncle. At first, there is a differential growth of the head and tail, and then there is the growth of the body, which shows changes in the ontogenetic priorities of feeding, swimming, and breathing capacities. Our results are very important for ecology, systematics, and hatchering, especially in terms of ontogenetic variation in morphology, growth, feeding, behavior, and mortality of P. reticulatum. RESUMO Este estudo descreveu o desenvolvimento inicial de Pseudoplatystoma reticulatum, bem como as mudanças nos padrões de crescimento, testando a hipótese da ocorrência de crescimento diferencial durante a ontogenia inicial da espécie. Variáveis morfométricas e merísticas foram analisadas durante os períodos embrionário, larval e juvenil, assim como os coeficientes de crescimento alométrico para larvas e juvenis. Os ovos apresentaram diâmetro médio de 1,79 mm e espaço perivitelino amplo (23,41%). O comprimento total (CT) das larvas variou de 3,05 a 125,72 mm e o número total de miômeros de 45 a 50 (pré-anal=13-16 e pós-anal=30-35). A pigmentação inicial é escassa, concentrada nas extremidades do saco vitelino. A partir do estágio de flexão a pigmentação se intensifica, formando uma faixa longitudinal que se estende do focinho ao opérculo e duas no corpo, uma dorsal e outra ventral, que se unem no pedúnculo caudal. Inicialmente há um crescimento diferenciado da cabeça e da cauda, com posterior crescimento do tronco, que demonstra mudanças nas prioridades ontogenéticas para as capacidades de alimentação, natação e respiração. Nossos resultados são de grande importância para a ecologia, sistemática e larvicultura, especialmente em termos de variação ontogenética na morfologia, crescimento, alimentação, comportamento e mortalidade P. reticulatum.

This study investigated the effect of ip injection of an oil-adjuvant vaccine and dietary phosphorus (P) level on the incidence of sexual maturation and occurrence of skeletal deformities in Atlantic salmon. Triplicate groups (12 × 12 m sea cages) of vaccinated (V) and unvaccinated (UV) Atlantic salmon underyearling smolts were fed diets with 0.6% (0.6P) or 0.9% available phosphorus (0.9P) from seawater transfer in mid-October and 3 months onwards, and then a commercial diet for a further 11 months. Both vaccination and 0.9% available phosphorus significantly increased the proportion of immature fish. V significantly reduced the incidence of mature females, while 0.9P significantly reduced the incidence of mature males. In addition, there were always relatively fewer mature V than UV males within each of the six sea-cages (three per diet). At the end of the period on different test diets, fish fed the 0.6P diet displayed significantly lower mechanical stiffness of the vertebral bodies than fish fed the 0.9P diet, but the mean values were both relatively high, which indicated that both groups enjoyed good mineral status. There was no effect of vaccination on stiffness, and there were no dietary or vaccination effects on the occurrence of externally detectable skeletal deformities (vertebral column, operculum, jaw). This is the first study to show that dietary phosphorus and vaccination can influence sexual maturation in fish. The results show that early seawater diets for underyearling Atlantic salmon smolts must be sufficient in phosphorus to prevent unwanted sexual maturation during on-growth in seawater.

Naturally occurring predators of the genus Orius (Heteroptera: Anthocoridae) often suppress agricultural pests in insecticide-free environments. Knowledge of Orius species composition in the field is important because species vary in their biology, prey preference, and ability to suppress pest populations. However, field-collected Orius bugs are often female biased and the identification of Orius females may be unreliable and time consuming. Identification of Orius species based on egg structure may allow easy and nondestructive identification of females, by inspecting the eggs they deposit, and identification of species that reproduce in the field. The aim of the current study was to illustrate how several Mediterranean Orius species could be identified using egg opercula. For this purpose, the structure of the operculum was described for eggs deposited by field-collected females, based on scanning electron microscope images. Then, adult males that developed from these eggs were identified to species by genitalia examination. A detailed description of diagnostic features of the operculum is given for each of four Orius species: O. albidipennis (Reuter), O. niger Wolff, O. laevigatas (Fieber), and O. horvathi (Reuter). Characterizing the structure of egg opercula of additional Orius species would facilitate ecological and biological control research in other parts of the world.

The effect of ploidy on scale-cover pattern in linear ornamental (koi) common carp Cyprinus carpio was investigated. To obtain diploid and triploid linear fish, eggs taken from a leather C. carpio female (genotype ssNn) and sperm taken from a scaled C. carpio male (genotype SSnn) were used for the production of control (no shock) and heat-shocked progeny. In heat-shocked progeny, the 2 min heat shock (40° C) was applied 6 min after insemination. Diploid linear fish (genotype SsNn) demonstrated a scale-cover pattern typical for this category with one even row of scales along lateral line and few scales located near operculum and at bases of fins. The majority (97%) of triploid linear fish (genotype SssNnn) exhibited non-typical scale patterns which were characterized by the appearance of additional scales on the body. The extent of additional scales in triploid linear fish was variable; some fish had large scales, which covered almost the entire body. Apparently, the observed difference in scale-cover pattern between triploid and diploid linear fish was caused by different phenotypic expression of gene N/n. Due to incomplete dominance of allele N, triploids Nnn demonstrate less profound reduction of scale cover compared with diploids Nn.

Two preparations of opercular bones for estimating age of longnose suckers Catastomus catastomus revealed that annuli were obscured by dense bone and undetected when the whole operculum technique was used. By thin-sectioning the opercula, we removed the dense bone, revealing previously obscured annuli. Using opercula collected from older fish in Labrador, Canada, we found that the dense bone overgrowth led to an overall age bias of 1 year. When samples were broken into groups based on sectioned ages, however, there were minimal differences in age between the two techniques for fish age 6 and younger and a 2-year age difference for fish estimated to be age 10 and older. To compare precision in locating annuli between the two techniques, we calculated coefficient of variation values among independent determinations. Both techniques demonstrated low variance, however, age determinations had greater variation with thin-sectioning than with whole opercula interpretations. Therefore, we conclude that c...

A population of the Australian mudskipper, Periophthalmus minutus, was found to inhabit mudflat that remained uncovered by tide for more than 20 days in some neap tides. During these prolonged emersion periods, P. minutus retreated into burrows containing little water, with a highest recorded salinity of 84 ± 7.4 psu (practical salinity unit). To explore the mechanical basis for this salinity tolerance in P. minutus, we determined the densities of mitochondria-rich cells (MRCs) in the inner and outer opercula and the pectoral fin skin, in comparison with P. takita, [corrected] from an adjacent lower intertidal habitat, and studied morphological responses of MRCs to exposure to freshwater (FW), and 100% (34-35 psu) and 200% seawater (SW). Periophthalmus minutus showed a higher density of MRCs in the inner operculum (3365 ± 821 cells mm(-2)) than in the pectoral fin skin (1428 ± 161) or the outer operculum (1100 ± 986), all of which were higher than the MRC densities in p. takita. [corrected]. No mortality occurred in 100% or 200% SW, but half of the fish died within four days in FW. Neither 200% SW nor FW exposure affected MRC density. Transfer to 200% SW doubled MRC size after 9-14 days with no change in the proportion of MRCs with apical pits or plasma sodium concentration. In contrast, transfer to FW resulted in a rapid closing of pits and a significant reduction in plasma sodium concentration. These results suggest that P. minutus has evolved morphological and physiological mechanisms to withstand hypersaline conditions that they may encounter in their habitat.

In teleost fishes, 11-ketotestosterone (11KT) is a critical androgen regulating primary and secondary sex characteristics. In the sexually dimorphic Lythrurus fasciolaris (Cyprinidae), dominant nuptial males display heavy tuberculation on the head and nape, dark dorsolateral vertical bars, and dramatic red coloration in the fins, venter, and operculum area. This study aimed to quantify 11KT circulating levels in males and females, and determine any correlation with key male reproductive status indicators such as nuptial coloration, size, and gonadosomatic index (GSI). Thirty-one wild-caught L. fasciolaris were divided into three groups according to reproductive status: dominant males (D), non-dominant males (ND), and females (F). Physical measurements, digital imaging, and blood samples were used to quantify body size, GSI, nuptial coloration, and 11KT circulating levels. Dominant males had higher 11KT levels and nuptial coloration traits compared to ND males and females (red area, hue, saturatio...

The growth, survival and tag retention of double-tagged [external FT4 lock-on (FT4) and internal passive integrated transponder (PIT)-tagged] Atlantic halibut Hippoglossus hippoglossus were compared to internal PIT-tagged controls in a randomized trial. The objective was to assess the suitability of these tags for monitoring the performance of individual fish in longitudinal trials under commercial cage-culture conditions in the lower Bay of Fundy, New Brunswick, Canada. The FT4 tags were chosen due to their similarity to tags used by investigators to track H. hippoglossus in the wild. A subset of the population randomly received an external FT4 tag inserted through the operculum and were monitored over a 1105 day period. The specific growth rate of FT4-tagged fish was significantly reduced in the first sea summer with no significant difference observed for the remainder of the trial. The differential growth in the first sea summer created a relative size advantage, permitting controls to increase in size significantly faster than FT4 fish in all subsequent periods. The FT4 tags did not significantly influence survival under normal commercial cage-culture conditions. Results, however, suggest that the survival of FT4-tagged H. hippoglossus may be compromised during stressful handling events. Tag retention of FT4 tags was acceptable with 76% of tags remaining at the end of the 1105 day trial. FT4 tags proved to be an effective method to identify individual H. hippoglossus, with the caveat that they seriously bias productivity measures in commercial research trials.

In India, oysters, clams, mussels and a few gastropods are local delicacies along the coastal region. Of these total catch, few marine gastropods are not utilized by the people because of lack of awareness about the rich nutritive value of the seafood products. Keeping this in mind, an attempt was made to study the shelf life of the pickled product developed from gastropods such as Chicoreus ramosus and Hemifusus pugilinus for a period of 8 and 6 months at ambient temperature (30 ± 2C). The acceptability of gastropod pickles decreased as free fatty acid, trimethylamine nitrogen, total volatile base nitrogen, total plate count and sensory scores increased (P

A gastropod fauna from the Permian (Capitanian) Akasaka Limestone from Japan is described. It is one of the most diverse known Permian gastropod faunas and consists of at least 74 species level taxa. Forty taxa have been identified to species level; the remainder are treated in open nomenclature because of insufficient preservation. In addition, three types of neritimorph opercula are present. One family, seven genera and 28 species are described as new by Nutzel. New taxa are the family Araeonematidae, the genera Coeloconulus, Asamiella, Costataenia, Akasakiella, Cerithiozone, Yochelsonistylus and Permocerithium, and the species Anomphalus japonicus, Anematina parva, Araeonema panthalassica, Coeloconulus panae, Trochonodus permianus, Goniasma fortecarinata, G.? nodifera, Vebericochlis mazaevi, Costataenia hayasakai, Trypanocochlea parva, Cerithiozone ornata, Cerithioides angulatum, Stegocoelia akasakaensis, Yochelsonistylus seussae, Y. felixi, Knightella hydrobiformis, Palaeostylus? irregularis, P. atten...

To understand the effects of predation by gastropods on juveniles of the Japanese spiny turban snail Turbo cornutus, a field survey and laboratory experiments were conducted. The species compositions of the order Neogastropoda inside turfs of articulated coralline algae (ACA) on the east coast of Sagami Bay were surveyed monthly, and the dominant species inside the ACA turfs were identified. Laboratory experiments were conducted to examine the effects of predation by the dominant neogastropods on small gastropods in ACA turfs. Turban snails, which inhabit ACA turfs during their juvenile stages, were predated by two muricid gastropods, Ergalatax contractus and Thais bronni, with the predation rate of E. contractus being significantly higher than that of T. bronni. While E. contractus could also predate two other species of gastropods, Anachis misera and Cantharidus japonicus, the predation rates on these two snails were significantly lower than on T. cornutus. The observed defensive behaviors were different among the three prey species, and the defensive strategy related to the calcified operculum of T. cornutus was not efficient against predation by E. contractus. It is concluded that the predation by E. contractus represents an important factor in the mortality of juvenile turban snails inside ACA turfs.

This study estimated the age of Hexaplex trunculus (Gastropoda: Muricidae) by analysing operculum growth marks. Surface striae and adventitious layers were counted in opercula of H. trunculus from the Ria Formosa Lagoon (southern Portugal) and from the Bizerte Lagoon (northern Tunisia), and in aquacultured individuals used for validation of the ageing technique. Operculum growth features were also compared between H. trunculus populations under contrasting environmental conditions (namely seawater temperature). Despite high inter-individual variability, all H. trunculus populations displayed a clear increasing trend in the number of striae and layers with increasing specimen size. The operculum marginal growth revealed that opercular deposition is not annual. Instead, a few growth marks are formed in the operculum each year, which was confirmed with reared specimens. In both ageing methods, considerable variation in the number of counts at a determined shell length indicates that operculum growth marks should be interpreted cautiously because they might not correspond accurately with individual age. Because of the subjectivity inherent to either method, counting striae and layers in opercula only provides rough age estimates of H. trunculus. published

Enteric redmouth disease (ERM), which is caused by Yersinia ruckeri, has not been reported in Japan. In the present study, virulence of the bacterium were assessed by experimental chal­ lenges with the rainbow trout Oncorhynchus mykiss and 4 indigenous fish species in Japan: yamame (masu salmon parr) O. masou masou, amago O. masou macrostomus, whitespotted char Salvelinus leucomaenis and ayu Plecoglossus altivelis. When intraperitoneally (ip) injected with the bacterium at a dose of 7.1 x 10 2 CFU/g fish body weight (BW), rainbow trout, char, yamame, and amago showed the cumulative mortalities of 100%, 60%, 30% and 30%, respectively. The cumulative mortalities of ip­ injected ayu with doses of 1.5 x 10 6 , 1.5 X 10 5 , 1.5 X 10 4 and 1.5 x 10 3 CFU/g BW were 87%, 47%, 13% and 0%, respectively. In addition, the cumulative mortalities of ayu immersed in water containing 1.7 x 10 8 and 1.7 x 10 7 CFU/mL of the bacterium were 60% and 6.7%, respectively. Typical clinical signs of ERM, such as reddening of the wall of the oral cavity, tongue, upper jaw, lower jaw, operculum, bases of fins, or skin around the anus, were observed in all dead salmonids but not in ayu. Instead, exophthal­ mos, hemorrhage in the eyes, ascites or hypertrophy of the kidney were often observed in dead ayu. These results indicate that Yersinia ruckeri is a potentially dangerous bacterium to freshwater aquacul­ ture in Japan.

Acanthochondria lilianae n. sp. (Copepoda: Chondracanthidae) is described and illustrated based on specimens of both sexes collected from inner surface of the operculum of the longtail southern cod, Patagonotothen ramsayi (Regan) (Perciformes: Nototheniidae), from the Patagonian Shelf, Argentina (42-48°S, 60-63°W). Acanthochondria lilianae n. sp. is characterized by the combination of a Type B-III antennule and Type A leg 2, in addition to both the cephalosome and the trunk being wider than long. The new species most closely resembles Acanthochondria incisa Shiino, 1955, Acanthochondria ophidii (Krøyer, 1863), Acanthochondria priacanthi Shiino, 1964, and Acanthochondria tasmaniae Heegaard, 1962, but differs from these species in the general measurements and proportions of the body, shape and size of head, shape and size of genitoabdomen, and fine details of appendages such as the armature of antennule, ornamentation of both pairs of legs, number of teeth on mandible and maxilla, and ornamentation on maxilliped. This is the first Acanthochondria species recorded from a nototheniid and the second southernmost record of a species of this genus in the southwestern Atlantic Ocean.

The results of the analysis of the stable oxygen isotopes content in shell carbonates for the purpose of the individual age determination of the Rapana venosa gastropod (Valenciennes 1846) are presented. The data acquired via this method agreed with the number of spawning marks on the shell surface. Additionally, the duration of the seasonal extrema can indicate the velocity of the shell’s growth throughout the mollusk life, and the relative δ18O value in the shell’s near-apex increments, the season when a young shell comes out of its cocoon. It has been shown that the common method of growth rings counting at the operculum is unreliable for a shell’s age determination. The distinguishing of modal classes is ineffective as well, since the corridor of the variations in size for coeval individuals is very broad. Apparently, such variable characteristics as the growth rate, the wall’s thickness, and the relative weight are greatly dependent on the alimentary conditions, which are unequal even in the same biotope.

Ontogenetic changes in the location, size, density and morphology of chloride cells in the Nile tilapia Oreochromis niloticus adapted to fresh and brackish water are described using Na(+) /K(+) -ATPase immunohistochemistry, light microscopy (LM), scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). The pattern of chloride cell distribution changed during development under both treatments, with chloride cell density decreasing significantly from hatch to 7 days post-hatch, but appearing on the inner opercular area at 3 days post-hatch and increasing significantly thereafter (P < 0·05). Chloride cells were always denser in fresh- than in brackish-water larvae. In both treatments, chloride cells located on the outer operculum and tail showed a marked increase in size with age, but cells located on the abdominal epithelium of the yolk sac and the inner operculum showed a significant decrease in size (P < 0·05). Chloride cells from brackish-water adapted larvae from 1 day post-hatch onwards were always significantly larger (P < 0·05) than those from freshwater-adapted larvae. SEM revealed structural differences in chloride cell apical morphology according to environmental conditions. There appears to be clearly defined temporal staging of the appearance of adaptive mechanisms that confer an ability to cope with varying environmental conditions during early development.

Dissolved gas supersaturation is hazardous to fish and can result in gas bubble disease (GBD). Signs of GBD typically include bubbles in the eyes, fins, skin, lateral line, and gill filaments. Ocular abnormalities in diseased salmonids typically occur after aberrant gas production in the eyes. In this study, freshwater rainbow trout Oncorhynchus mykiss were exposed experimentally to percent total gas pressure (TGP%) levels of 104% (control) and 115%. No mortalities occurred during the 7-d experimental period. Effects of GBD were observed externally as a darkened skin, exophthalmia, localized hemorrhage in the eye, and gas bubbles on the operculum. Additional signs included increased swimming activity and, more frequently, panic episodes. Carbonic anhydrase (CA) enzyme activities from the lens and retina were determined at days 0, 1, 3, 5, and 7 of the study. Venous blood gases were also measured on day 7. Retinal pH did not differ between normal and affected fish, but blood characteristics such as the partial pressure of O2, partial pressure of CO2, carboxyhemoglobin level, and bicarbonate ion concentration were significantly elevated in affected fish relative to normal fish. Venous blood pH and oxyhemoglobin levels were not significantly different between affected and normal fish. Patterns of response to total dissolved gas levels differed between the lens and the retina. Mean CA activities in the lenses of fish exposed to a TGP% level of 115% were significantly below those of control fish. However, retinal CA activities did not significantly differ between the two groups over the course of the experiment. These findings show that dissolved gas supersaturation reduces CA activity in the rainbow trout lens.

Summary The aim of the study was to determine the distribution and relative frequency of Glyptosternon maculatum taste buds (TB) using paraffin sectioning, the HE staining method and light microscopy. TBs were found on a variety of surface body areas (lips, barbels, lateral, ventral and dorsal areas, and the dorsal, pelvic, pectoral, anal and adipose fins), as well as in the oropharyngeal cavity. In the epithelium of histological figures of sampled body parts, TB was pear-shaped from the bottom to the top. The ratio of height/width value of the taste bud was above 1.0, with a range from 1.2 to 2.0. Highest TB frequencies were in the mandibular outer barbel (18.5 ± 3.7 mm−2), mandibular inner barbel (17.1 ± 5.4 mm−2), nasal barbel (16.8 ± 4.2 mm−2) and maxillar barbel (15.9 ± 2.7 mm−2), lips (14.6 ± 3.6 mm−2) and oropharyngeal cavity (13.2 ± 3.5 mm−2). TBs occurred in moderate quantities on the forehead (6.9 ± 2.1 mm−2), anal fin (5.8 ± 2.3 mm−2), and La2 (3.9 ± 1.6 mm−2, between pelvic and anal fins), then decreased to a few in the La1 area (3.4 ± 1.3 mm−2), operculum (2.5 ± 1.3 mm−2) and other examined areas. Type I (elevated), type II (slightly elevated) and type III (not elevated or sunken) TBs were found in the epithelium of various sampling locations. These are the first descriptions of taste buds in G. maculatum.

Thirty-one gross abnormalities that have been observed in tilapia are described: 10 fin, five eye, five jaw, four body shape, three head, two yolk sac, one operculum, and conjoined twins. Twenty-one have been described in published papers; the others were obtained from a survey. Breeding experiments revealed that three were heritable, while six were not heritable. Five could be caused by a bacterial infection, and one could be produced by a fungus. Four deformities were in offspring of males that had been injected with methyl methane sulphonate. Three were produced when sperm was treated with methyl methane sulphonate. Six were observed during sex reversal studies, and one was found following heat shock of fertilized eggs. Three were observed in polluted river water. The cause of other deformities is not known.

Summary In order to evaluate the phenotypic plasticity of introduced pikeperch populations in Tunisia, the intra- and interpopulation differentiation was analysed using a biometric approach. Thus, nine meristic counts and 23 morphological measurements were taken from 574 specimens collected from three dams and a hill lake. The univariate (anova) and multivariate analyses (PCA and DFA) showed a low meristic variability between the pikeperch samples and a segregated pikeperch group from the Sidi Salem dam which displayed a high distance between mouth and pectoral fin and a high antedorsal distance. In addition, the Korba hill lake population seemed to have more important values of total length, eye diameter, maximum body height and a higher distance between mouth and operculum than the other populations. However, the most accentuated segregation was found in the Lebna sample where the individuals were characterized by high snout length, body thickness, pectoral fin length, maximum body height and distance between mouth and operculum. This study shows the existence of morphological differentiations between populations derived from a single gene pool that have been isolated in separated sites for several decades although in relatively similar environments.

The incidence of parasitic marine isopods among wild 100 Argyrops filamentosus fish was studied. Specimens were subjected to clinical, postmortem and parasitological examinations for detection of isopod infestations. The detected parasite was Cymothoa spinipalpa. The infestation rate was 9%, one per fish. Cymothoa spinipalpa was observed in the gill chamber and buccal cavity of the host. Slight protrusion of gill cover (operculum), atrophy and haemorrhage at site of attachment were noticed. The morphological characteristics of this species were described in details using light and scanning electron microscopy and discussed.

Schejter, L. and Mantelatto, F.L. 2011. Shelter association between the hermit crab Sympagurus dimorphus and the zoanthid Epizoanthus paguricola in the southwestern Atlantic Ocean. —Acta Zoologica (Stockholm) 92: 141–149. The available literature on zoanthid–hermit crab associations deals only with records of this phenomenon, providing no detailed information. We describe, for the first time, the shell-like colonies of Epizoanthus paguricola associated with the hermit crab Sympagurus dimorphus from benthic samples taken in the Argentine Sea, between 85 and 131 m depth, and provide information about morphometric relationships between the hermits and the zoanthids. In total, 260 specimens (137 males and 123 females) of S. dimorphus were collected, 240 (92.3%) of which were living in symbiosis with E. paguricola. The remaining 20 (7.7%) were living inside gastropod shells. As the initial structure of the pseudoshell, 12 different gastropod species were found (all were almost totally covered with colonies of E. paguricola). The hermit crab lives in the spiral cavity inside the soft colony, which seemed to be slightly different depending on the initial gastropod. Aperture pseudoshell morphology did not seem to be related to the sex of the hermit crab host, although males showed larger apertures for a given colony size. This fact is probably related to a larger size of male’s cheliped (sexual dimorphic character) used like a gastropod operculum and that may serve as a template for the growing of the aperture pseudoshell edge. The number of epizoanthid polyps per colony increased in relation to the weight of the colony and to the size of the hermit crab. A process of selection of the initial shell was evident, because species of Naticidae were not the most common gastropods in this benthic community, but were those most used by hermit crabs (>60%). The puzzling association between hermit crab, shell and zoanthid presumably occurs during the hermit juvenile phase, when the crab occupies a small shell, and a zoanthid larva settles on it. Given the close relationship between S. dimorphus and E. paguricola found in this region, we support the idea that due to the low availability of adequate gastropod shells for hermit life cycle, this association allows the establishment and the continuity of the hermit crab population in the studied area.

An endangered freshwater fish, Opsaridium peringueyi , was studied from January, 2009 to December, 2009. The analysis of the environmental conditions indicated that the fish is found in streams with moderate to fast flow, high oxygen levels, a depth greater than 0.6 m and temperatures between 10 and 24 °C. O. peringueyi is sexually dimorphic with males growing at a faster rate and attaining a larger size than females. The breeding biology of this species was investigated in glass aquarium tanks. The spawning behaviour is described for the first time. The breeding colour of the male is deep red on the operculum, ventral part, caudal and ventral fins. The breeding colour in the female is the same as the male except the red colour is lighter. The breeding of O. peringueyi is a four stage process which begins with the appearance of breeding colour culminating in the laying of eggs after courtship. Temperature, flow-rate, conductivity and substrate were identified as the environmental cues important in the reproduction of this species. All these factors had a significant effect on the breeding activity of O. peringueyi . The possible effect of climate change on O. peringueyi is discussed.

Two morphological groups of Pseudodiaptomus inopinus were detected in western Japan. One was from the Japan Sea and Tsushima Strait coasts and the other from the Pacific coast including the west and east coasts of Kyushu Island. Differences in fe- males were seen in the posterior processes of the genital operculum, shape of the genital flap, and medial spinules on the first exopodal segment of the fifth leg, and those in males were in the shape of the first exopodal segment of the fifth left leg, and position of the me- dial process on the third exopodal segment of the fifth right leg. Proportional length of the caudal rami also differed in both sexes. Among these morphologies, the length of the genital operculum process discretely separated each group, but variations in the other morphometric characters were overlapping. Geographic distributions of the two groups were separated with a boundary between two rivers on the northwest coast of Kyushu Island. These results indicate that P. inopinus in Japan is a species complex and specimens from the Japan Sea and Pacific coasts belong to different species.