Search

Ocean sunfishes or molas (Molidae) are difficult to study as a result of their extensive movements and low densities in remote waters. In particular, little is known of the environmental niche separation and differences in the reproductive or movement ecology of molids in sympatry. We investigated spatiotemporal dynamics in the distribution of the common mola Mola mola, sharptail mola Masturus lanceolatus, and slender mola Ranzania laevis in the eastern North Pacific. We used observer data from a commercial fishery consisting of 85000+ longline sets spanning 24 yr, >50° in longitude, and >45° in latitude. Satellite altimetry analysis, species distribution modeling, and multivariate ordination revealed thermal niche separation, spatiotemporal segregation, and distinct community associations of the 3 molid species. Our quantitative findings suggest that the common mola is a more temperate species, while slender and sharptail mola are more (sub)tropical species, and that slender (and possibly also sharptail) mola undergo spawning migrations to the region around the Hawaiian Islands. In addition, we identified potential effects of fishing gear type on molid catch probability, an increasing trend in catch probability of a vulnerable species perhaps related to a shift in the distribution of fishing effort, and the possible presence in the fishery of a fourth molid species being misidentified as a congener, all of which are important conservation considerations for these enigmatic fishes.

The unusual appearance of ocean sunfish and their relatives (Molidae), including exaggerated dorsal and anal fins and a missing caudal fin, raises a question of how they swim. In this chapter, the locomotory systems and biomechanics of ocean sunfish are reviewed based on recent morphological, kinematic, and behavioral studies. Ocean sunfish flap their dorsal and anal fins laterally to produce lift-based propulsion forces, a unique swimming style in which two fins with different origins function as paired vertical wings. The two fins are symmetrical within individuals, despite ontogenetic changes in shape. Unlike many other teleosts with axial musculature that drive caudal fins, sunfish have two sets of muscles, separated by the horizontal septum. These muscles run dorsoventrally to drive the dorsal and anal fins. Aerobic red muscles are located medial to anaerobic white muscles, an arrangement reminiscent of endothermic (i.e., high body temperature) fishes, although sunfish are apparently ectothermic. The thick, white sub-skin layer (hypodermis) has exoskeletal and possible buoyancy functions as well (adult Molidae lack a swim bladder). It is suggested that their conspicuous swimming style and associated morphology enable energy-efficient swimming at a cost of reduced acceleration and manoeuvring abilities, allowing sunfish to search the open ocean for patchily distributed prey (e.g., gelatinous zooplankton).

While ocean sunfishes hold the vertebrate record for having the most ova in a single female, information on the natural history of their larvae and juveniles has yet to be collated. This chapter includes the most comprehensive compilation of larval molid records to date, and places the records within a global spatial context. Gathered from natural history museum collections, modern ichthyoplankton sampling efforts and historical records dating back to the 1800s, a total of 452 records were collected comprising 9,770 larvae in total: 285 Masturus, 84 Mola spp., 61 unspecified Molidae and 9,340 Ranzania (340 of which were eggs). Ranzania was primarily reported from the Sargasso Sea, Northern Brazil, Hawai’i and southern Polynesia. Masturus, were reported from the Sargasso Sea and at scattered locations across both Atlantic and Pacific Ocean basins. Lastly, for Mola spp., records existed for Eastern Australia and the Eastern USA. Larval stages of early development for each molid genera are identified, described, and illustrated with original drawings. Larval records also include larvae extracted from the guts of 26 different predator species: 17 large pelagic piscivorous fishes from six families, and nine seabirds species from five families. While this chapter cannot be considered an exhaustive compilation of all molid larval knowledge, it does provide a foundation on which to build a more extensive molid larval database. It also underscores the importance of collecting hydrographic metadata to accompany each record. We hope that future studies can use this review to help locate additional spawning sites and achieve the critical mass of data required for habitat suitability modelling. Such a vantage point would allow an assessment of how spawning sites may be impacted by ongoing environmental and anthropogenic changes and inform management plans.

The Ocean Sunfish or Common Sunfish or Common Mola (Mola mola, Linnaeus 1758) belongs to the Molidae family...

The taxonomy of the ocean sunfishes (Molidae) has a complicated history. Currently, three genera and four species are recognized, including two in the genus Mola (M. mola and M. ramsayi). In 2009, a genetic study revealed a potential third species, Mola species C, in Southeast Australian waters. Concentrating on this region, we obtained samples and morphological data from 27 Mola sp. C specimens, genetically confirmed the existence of this species (mtDNA D-loop and cytochrome c oxidase 1), and established its morphology across a size spectrum of 50–242 cm total length. Mola sp. C is diagnosed by clavus meristics [15–17 fin rays (13–15 principal, 2 minor), 5–7 ossicles, paraxial ossicles separate], clavus morphology (prominent smooth band back-fold, rounded clavus edge with an indent), and body scale morphology (raised conical midpoints, non-branching). This species does not develop a protruding snout, or swollen dorso- or ventrolateral ridges. Body proportions remain similar with growth. A review of the historic literature revealed that Mola sp. C is a new, hitherto undescribed species, M. tecta, which we describe and diagnose, and that it is the first proposed addition to the genus Mola in 125 years. Its core distribution is likely in the temperate waters of the Southern Hemisphere.

Ocean sunfishes, with their peculiar morphology, large size, and surface habits, are valuable assets in ecotourism destinations worldwide. This study investigates site fidelity and long-range movements of short ocean sunfish, Mola ramsayi (Giglioli 1883), at Punta Vicente Roca (PVR) off Isabela Island in the Galapagos Islands. Five individuals were tracked between 32 and 733 days using ultrasonic receivers and transmitters. Two of the 5 were also tracked with towed pop-off satellite tags. One travelled to the equatorial front covering 2700 km in 53 days, with dive depths in the upper 360 m at temperatures between 9.2°C and 22°C. During its westward travel, dives extended to 1112 m (the deepest depth yet recorded for Molidae) into temperatures ranging between 4.5°C and 23.2°C. The remaining four individuals demonstrated site fidelity to PVR and were detected at the site between 128–1361 times for a total of 3557 reports. Forty-eight percent of the reports occurred during daytime hours and 52% after dark. Presumed cleaning session durations had a median of 15 minutes and a maximum of nearly 100 minutes. No other ultrasonic arrays around Galapagos or in the Eastern Pacific regional network recorded the presence of tagged individuals. These data are combined with tourist vessel sightings and submersible observations to confirm Punta Vicente Roca as an important sunfish hotspot.

We employed molecular systematic analysis based on mitochondrial D-loop sequences to identify two specimens of ocean sunfish from Omani coastal waters that had previously been identified morphologically as Mola mola (Linnaeus, 1758) and M. ramsayi (Giglioli, 1883). Of the three molecular species that are recognized globally, Mola sp. A, Mola sp. B, and Mola sp. C, we confirmed that both specimens from Oman are Mola sp. A. This result suggested a broader distribution of this species than had ever been thought, but it also revealed a discrepancy between morphological and genetic characters in Mola taxonomy. We reexamined the morphology of the two specimens from Oman to clarify the extent to which the key morphological features correspond with molecular genetic identifications, and discovered errors in the original reports on both specimens.

No studies document essential (calcium, magnesium, phosphorus, potassium, sodium), trace (barium, boron, chromium, cobalt, copper, iron, manganese, molybdenum, selenium, zinc) or toxic element (antimony, arsenic, cadmium, lead, mercury, thallium) concentrations in any members of the family Molidae, including the world's largest bony fish, the ocean sunfish (Mola mola). Here, we analyzed 21 elements in the liver of one M. mola. These values were compared to liver concentrations in multiple species with spatial and dietary overlap. Concentrations of calcium (3339 ppm wet weight) and iron (2311 ppm wet weight) were extremely elevated in comparison to a number of other fish species, indicating that calcium and/or iron toxicity may have occurred in this animal. Concentrations of toxic elements were generally low, with the exception of cadmium (3.5 ppm). This study represents the first report of essential, trace and toxic elements in this species.

Information about the ocean sunfish, Mola mola (Pisces Molidae), coming from an individual captured off Los Cocos, northeast Magdalena Department, is presented.

Ocean sunfishes, Molidae, comprise the world’s heaviest bony fishes. They include the short mola,Mola ramsayi(Giglioli 1883), an important tourist draw at Nusa Penida and Nusa Lembongan, Bali, where SCUBA divers can observe ectoparasite-laden individuals being cleaned by smaller reef fishes. Despite widespread appeal, little is known about these fishes relative to regional oceanography. We present the first behavioral information for this species anywhere in the world. Satellite tag data indicate a wide thermal range (10–27.5°C) with depth occupation mostly (95%) in the upper 250 m and habitat preference near the bottom of the warm surface layer. One tag popped off as scheduled after 6 months off Nusa Penida, M. ramsayiin eastern regions of Indonesia, such as Alor, behavioral information of this species is essential for effective management and conservation of this valuable marine ecotourism asset.

Relatively little is known about the biology and ecology of the world’s largest (heaviest) bony fish, the ocean sunfish Mola mola, despite its worldwide occurrence in temperate and tropical seas. Studies are now emerging that require many common perceptions about sunfish behaviour and ecology to be re-examined. Indeed, the long-held view that ocean sunfish are an inactive, passively drifting species seems to be entirely misplaced. Technological advances in marine telemetry are revealing distinct behavioural patterns and protracted seasonal movements. Extensive forays by ocean sunfish into the deep ocean have been documented and broad-scale surveys, together with molecular and laboratory based techniques, are addressing the connectivity and trophic role of these animals. These emerging molecular and movement studies suggest that local distinct populations may be prone to depletion through bycatch in commercial fisheries. Rising interest in ocean sunfish, highlighted by the increase in recent publications, warrants a thorough review of the biology and ecology of this species. Here we review the taxonomy, morphology, geography, diet, locomotion, vision, movements, foraging ecology, reproduction and species interactions of M. mola. We present a summary of current conservation issues and suggest methods for addressing fundamental gaps in our knowledge.

Phylogenetic analyses were conducted using complete nucleotide sequences of the D-loop in the mitochondrial genome of Mola specimens, collected mainly in Japanese waters, to clarify the genetic features and distribution patterns of Mola sunfishes. Two significantly distinct groups (designated A and B) were present in the genus, with a considerable net nucleotide sequence divergence between the two (8.4%). The two groups occurred sympatrically around the Japanese coast, as previously suggested by Sagara et al. (2005). Group A occurred mostly on the Pacific coast of eastern Japan, while group B was widely distributed along the Kuroshio Current, strongly suggesting different migration routes for each group. The morphological characteristics of the two group specimens were differentiated via the head bump, body proportions and shape of the clavus. Through the addition of Mola sequence data taken from outside Japan to our phylogenetic analyses, three independent groups, including groups A and B, were found, each with a wide geographical distribution, which suggests the presence of at least three independent species within the genus Mola.

Presence and habitat preference of two pelagic fish species—Mola mola and Ranzania laevis—are investigated from all available records obtained in the Adriatic from 1781 up to today. Absence of systematic investigations is overcome by relating their occurrences to the long-term meteorological and oceanographic data sets representing local conditions and processes. Seasonal and interannual distributions of these two species are significantly different and point to a possible different causes of their appearance. On the seasonal scale almost all findings of M. mola, with only a few exceptions, are from the warm part of the year, whereas R. laevis is appearing throughout the year with the highest number of individuals in December. Analysis of the interannual meteorological and oceanographic conditions indicates that occurrence of M. mola coincides with the sea warming, whereas the oceanographic conditions favourable for appearance of R. laevis are more complex and could be related to the abrupt change in the large scale atmospheric conditions. Changeable atmospheric conditions coincided with increased productivity in the Adriatic and increased number of zooplankton and small pelagic fish, which are the main food for R. laevis.

Mola mola is distributed from temperate to tropical oceans. The scarce reports on the occurrence of the species in the Uruguayan coast were based on incomplete morphological studies on collected specimens that could not properly discard the congeneric Mola ramsayi. This work constitutes confirmation of the occurrence of Mola mola in the coastal area of Uruguay, based on morphological characters of a specimen collected in April 2013. The fish occurred 100 m offshore in the Rio de la Plata estuary (at a depth of 5 m), in an area with a water temperature between 19 and 19.5°C. Morphometric data is provided. The specimen is preserved in the Museo Nacional de Historia Natural de Montevideo (Uruguay).

Ocean sunfish, family Molidae, are enigmatic members of the epipelagic fauna of all tropical and temperate oceans. A study, begun in 1998, initially focused on the population genetics of Mola mola Linnaeus 1758 immediately indicated high levels of genetic divergence in the d-loop and cytochrome b mitochondrial genes. This preliminary effort was expanded to include Masturus lanceolatus Lienard 1840, Ranzania laevis Pennant 1776, and representative sequences of other Tetraodontiformes. Analysis of the sequence data confirms that there are two species in the genus Mola, Mola mola and M. ramsayi Giglioli 1883, with the latter presumed to be limited to the southern hemisphere. There is an indication of inter-ocean subdivision within both species originating 0.05–0.32 and 1.55–4.10 million years ago, respectively. Given limited sample sizes, however, the divergence estimates are minimums and the isolating mechanisms remain speculative. The systematic analysis provided strong support for the sister taxa relationship between genera Masturus and Mola and the basal position of the genus Ranzania within the family, as well as the sister group relationship of the Tetraodontiform families Tetraodontidae + Diodontidae to the Molidae.

We determined the complete nucleotide sequences of the mitochondrial genomes for the three currently recognized species of ocean sunfish: Mola mola, Masturus lanceolatus, and Ranzania laevis (Tetraodontiformes: Molidae). Each genome contained the 37 genes as found in teleosts, with the typical gene order in teleosts. Bayesian, maximum-likelihood, and maximum-parsimony analyses were conducted with the data set comprising concatenated nucleotide sequences from 36 genes (excluding the ND6 gene) of three molids and four outgroups (three tetraodontiforms plus a caproid). The resultant trees supported monophyly of the Molidae and its intrarelationships ((Mola, Masturus), Ranzania), which were congruent with previous morphology-based hypotheses.

Ocean sunfish Mola mola are a seasonally common inhabitant of southern Californian waters, and comprise the largest bycatch component (29% of total catch) of the California drift gill- net fishery for swordfish. We used temperature and depth-sensing acoustic transmitters to quantify the fine-scale movement patterns of ocean sunfish near Santa Catalina Island, California. Eight ocean sunfish were tracked continuously over 24 to 72 h periods, during which oceanographic data were collected every 2 h. Geographical position and depth of tracked fish were analyzed in relation to oceanographic data and time of day. Ocean sunfish traveled a mean distance of 26.8 ± 5.2 (±SD) km d -1 . Horizontal movements were characterized by a significant decrease in rate of movement (ROM) dur- ing the first 6 h of night (median ROM = 0.76 km h -1 ) (SD = 0.31) as compared to the remaining night- time period (median ROM = 1.00 km h -1 )(SD = 0.39), whereas daytime ROM (median ROM = 1.22 km h -1 ) (SD = 0.58) was significantly higher than either nighttime period. Horizontal movements were highly directional, with angular concentration values (r) as high as 0.765 over the duration of entire tracks. Nocturnal vertical movements were confined to the surface mixed layer and thermocline, while diurnal vertical movements were often characterized by repeated dives below the thermocline. A significant relationship was found between maximum dive depth and the post-dive period spent in the mixed layer, suggesting that ocean sunfish may behaviorally thermoregulate between deeper daytime dives. The observed depth-distribution patterns of ocean sunfish indicate that lowering the depth of gillnets in the water column could significantly reduce bycatch of this species in the California drift gillnet fishery.

The occurrence of marine turtles in the diet of white sharks, Carcharodon carcharias, is reviewed worldwide. Four records of chelonians eaten by white sharks in the Mediterranean Sea are described, which on the basis of carapace remnants confirmed both the loggerhead Caretta caretta and green turtle Chelonia mydas to be preyed upon in those waters. The condition of these remains indicates that large white sharks can ingest turtles essentially intact. As well as falling prey to white sharks, we suspect that some interactions involve turtles being ‘grab-released’ in a non-predatory mannner and their survivability from such low-intensity bites or other mouthings may be quite high. The white shark may be the chief marine predator of adult chelonians in the Mediterranean Sea, albeit the impact of this predation upon turtle populations is nominal compared to other sources of mortality. Further, we give an account describing an adult ocean sunfish, Mola mola, in the stomach of a white shark taken in Italian waters.

aranta et al. (2012) recently challenged the paradigm that ocean sunfish Mola mola L. 1758 (Molidae) are obligate gelatinovores, basing their conclusion on isotopic differences between M. mola and co-occurring jellyfish in the Mediterranean Sea. The sampled M. mola (eight individuals

tierney m. thys, jonathan whitney, alex hearn, kevin c. weng, cesar pen~aherrera, l. jawad, j. alfaro-shigueto, j.c. mangel and stephen a. karl Ocean Sunfish Research and Tagging Program, 25517 Hacienda Place, Suite C Carmel, CA, 93923, Hawai’i Institute of Marine Biology, University of Hawai’i, Mānoa, PO Box 1346, Kāne’ohe, HI, 96744, Department of Wildlife, Fish, and Conservation Biology, 1088 Academic Surge, University of California, Davis, One Shields Avenue, Davis, CA, 95616-5270, Oceanography Department, Pelagic Fisheries Research Program, University of Hawai’i, Mānoa, Honolulu, HI 96822, Charles Darwin Foundation, Puerto Ayora, Santa Cruz Island, Galapagos, Ecuador, Natural Sciences, Auckland War Memorial Museum, Tamaki Paenga Hira, The Domain, Private Bag 92018, Victoria Street West, Auckland 1142, New Zealand, Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, TR10 9EZ, UK

The purpose of this work is to examine the gross visceral anatomy of ocean sunfish and angler using non-invasive imaging techniques: computed tomography imaging (CT) and magnetic resonance imaging (MRI). Similarities and differences in the internal organisation of these two species are verified. Both species lack a swimbladder and present a significant asymmetry in the hepatic lobes, an elongated bile duct terminating close to the stomach, a compact thyroid embedded in a blood lacuna, and very reduced brain and spinal cord. These observations are important in regard to the close relationships between Tetraodontiformes and Lophiiformes, established by several molecular works, but not yet confirmed by morpho-anatomical data. However the occurrence of these features has to be examined in other taxa before phylogenetic hypotheses are proposed.

The upperjaws of a fossil fish from the late Eocene of Russia (Kumsky Horizon, North Caucasus) are referred to the Molidae because of their uniquely derived features of highly striated external bone surfaces and laterally elongate trituration teeth, as well as overall morphological similarity to the upper jaws of molids. However, the Eocene upper jaws differ from those of all other fossil (previously known only from the Miocene and Pliocene) and extant molids by having the premaxillae separate and articulated medially by interdigitating processes (versus fused in the midline). The separation of the premaxillae in the new genus and species, Eomola bimaxillaria, is a retention of the plesiomorphic condition found in triodontids and tetraodontids.