---
title: "What the sources say about the Ocean Sunfish (Mola Mola) | AnimalTracks.wiki"
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# What the sources say about the Ocean Sunfish (Mola Mola) (*Mola mola*)

> 73 claims from the Ocean Sunfish (Mola Mola) profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Ocean Sunfish (Mola Mola)](https://animaltracks.wiki/animals/mola-mola/)

## Mola mola (Ocean Sunfish). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Mola_mola/

| The page says | The source says |
| :--- | :--- |
| Large sharks often prey on sunfish | Ocean sunfish are often preyed upon by large sharks and California sea lions (note: ADW is dated 2011; its sea-lion half is narrowed by FishBase's current page (next claim)) |
| cleaner fish such as wrasses and angelfish pick off its parasites when it occasionally visits kelp beds and reefs | occasionally venture into kelp beds and deep coral reefs in order to be cleaned of parasites by fishes such as wrasses (Labroides dimidiatus and Thalasoma lunare) and Emperor Angelfish |
| The clavus is the rudder-like structure at the rear of the fish | they instead have a clavus, which is a truncated tail, used more like a rudder than for propulsion |

## Mola mola (Linnaeus, 1758), Ocean sunfish. FishBase.

https://www.fishbase.se/summary/Mola-mola.html

| The page says | The source says |
| :--- | :--- |
| Up to 1.3 tonnes | max. published weight: 1.3 t (note: 1.3 t worded as 1.3 tonnes) |
| then floats flat at the surface between dives | Individuals often drift at the surface while lying on its side |
| Temperate and tropical oceans worldwide | Circumglobal: tropical and temperate zones of all oceans. (note: backs stats.habitat) |
| A body with no tail fin, steered by a stiff clavus rudder | The caudal fin is replaced by a rudder-like structure called (note: backs stats.superpower) |
| The ocean sunfish (Mola mola) can grow past 3 meters long and weigh up to 1.3 tonnes | Max length : 333 cm TL male/unsexed; ... max. published weight: 1.3 t (note: 333 cm TL is worded as 'past 3 meters'; a maximum, so 'can grow') |
| California sea lions go after the juveniles in Monterey Bay | Juveniles are victims of California sea lions in Monterey Bay (note: 'go after' is the phrasal verb for hunting (the source's 'are victims of'), not a sequence; FishBase is current and narrows ADW 2011's general sea-lion line) |
| A Mola mola can grow past 3 meters long and weigh up to 1.3 tonnes | Max length : 333 cm TL male/unsexed; ... max. published weight: 1.3 t (note: 333 cm TL is worded as 'past 3 meters') |
| Its name comes from the Latin for millstone | Etymology: Mola: Latin, mola, -ae = stone mill; because of the shape of this fish |
| One 1.5-meter female was found carrying about 300 million eggs, the largest clutch estimate for the species | 300 million eggs found in a 1.5 m long female ... This is the largest clutch estimate for this species (note: was 'A female can carry roughly 300 million eggs in one spawning': the figure is one 1.5 m female, and FishBase calls the species a multiple spawner, so not one spawning) |

## Ocean Sunfish. Oceana.

https://oceana.org/marine-life/ocean-sunfish/

| The page says | The source says |
| :--- | :--- |
| then floats flat at the surface between dives | Because they must sometimes dive into deep, cold waters to catch their prey, these fish will warm up by basking on their side at the water (note: the 'between dives' half) |
| juveniles can pack on up to 0.82 kilograms a day | they can grow up to 0.82 kilograms (1.8 pounds) every single day |
| consistent with basking between dives to recover warmth | these fish will warm up by basking on their side at the water (note: backs 'basking') |
| They are most likely warming back up after cold, deep dives | Because they must sometimes dive into deep, cold waters to catch their prey, these fish will warm up by basking on their side at the water (note: hedged 'most likely' because Nakamura et al. 2015 only 'suggest' it and the Australian Museum quotes Potter and Howell 2010 finding no evidence for it; reviewer cut 'not sunbathing for fun') |

## Ocean Sunfish, Mola mola. Australian Museum.

https://australian.museum/learn/animals/fishes/ocean-sunfish-mola-mola/

| The page says | The source says |
| :--- | :--- |
| with no tail fin | These interesting fish are completely without a caudal fin (note: reviewer: replaces 'finless'; sunfish have dorsal, anal and pectoral fins, only the caudal fin is missing) |
| tagged fish spent most of their time in the top 200 meters | over 80% of time in the top 200 m (note: backs stats.habitat; kept at the tagging study's scope; the Australian Museum page quotes this figure from Potter and Howell 2010) |
| and one dived to 844 meters | The maximum depth recorded by any fish was 844 m. (note: backs stats.habitat; the page quotes this from Potter and Howell 2010. Reviewer cut 'to feed', which no source ties to that dive) |
| Jellyfish, comb jellies and siphonophores | Ocean Sunfish feed on jellyfish, salps, ctenophores (note: backs stats.diet; 'comb jellies' is the common name for ctenophores; siphonophores backed by nakamura-2015 below. Reviewer dropped 'as adults': no source gives the adult diet as such) |
| the clavus, the sunfish's rudder-like rear end, has a wavy, frilled edge in Mola mola and a rounded one with no indent in M. alexandrini | Mola mola can be identified from its wavy (frilly) clavus edge, 11-14 clavus fin rays ... (the clavus is round without an indent in Mola alexandrini and rounded with an indent in Mola tecta) (note: reviewer: 'smooth' replaced by the source's own 'without an indent') |
| Sunfish have no tail fin | These interesting fish are completely without a caudal fin |
| one tracking study logged a dive to 844 meters | The maximum depth recorded by any fish was 844 m. (note: the page quotes this from Potter and Howell 2010) |
| a nod to its rounded shape | the name Mola comes from the Latin word for millstone and refers to the rounded shape of the fish (note: was 'round, flattened shape'; neither source says flattened) |
| its family, Molidae, includes the largest bony fish in the world | Sunfish are from the family Molidae and are the largest bony fish in the world. |

## Jing et al. (2015). Mola mola. The IUCN Red List of Threatened Species 2015: e.T190422A1951231.

https://doi.org/10.2305/iucn.uk.2015-4.rlts.t190422a1951231.en

| The page says | The source says |
| :--- | :--- |
| Vulnerable | IUCN Red List category: Vulnerable (VU). (note: backs stats.conservationStatus; FishBase lists the same category under Red List version 2025-2 (assessed 07 June 2011), so it is current) |

## Sawai & Nyegaard (2022). A review of giants: Examining the species identities of the world's heaviest extant bony fishes (ocean sunfishes, family Molidae). Journal of Fish Biology.

https://doi.org/10.1111/jfb.15039

| The page says | The source says |
| :--- | :--- |
| For a long time it also carried a bigger title: the world's heaviest bony fish, at around 2,300 kilograms | The world's heaviest extant bony fish has long been considered the ocean sunfish Mola mola (family Molidae). However, recent taxonomic research suggests the world record specimen (2300 kg) was actually a misidentified giant sunfish M. alexandrini. (note: 'for a long time' for the source's 'long been considered' (was 'for decades')) |
| A 2022 review of giant-sunfish records found that the specimen behind that number wasn't Mola mola | we confirm that the world's heaviest extant bony fish specimen actually weighed was a female M. alexandrini (2300 kg, 272 cm total length) captured from Kamogawa, Chiba Prefecture, Japan, on August 16, 1996. (note: 2022 is the paper's own publication year; 'wasn't Mola mola' reflects the paper's own confirmed finding, not the earlier hedged 'suggests' sentence) |
| It was a giant sunfish, Mola alexandrini, a separate species caught off Japan in 1996 | the world's heaviest extant bony fish specimen actually weighed was a female M. alexandrini (2300 kg, 272 cm total length) captured from Kamogawa, Chiba Prefecture, Japan, on August 16, 1996 |
| the same review concluded M. alexandrini is the only living bony fish researchers could confirm above 2,000 kilograms | we conclude that M. alexandrini is the only extant bony fish species we could confirm that exceeds 2000 kg (note: 'living' restores the source's 'extant'; 'above' is the source's 'exceeds') |
| So Mola mola is enormous, just not the outright record-holder its old reputation claims | we confirm that the world's heaviest extant bony fish specimen actually weighed was a female M. alexandrini (note: follows from the confirmed record specimen being M. alexandrini; 'enormous' rests on the 1.3 t above) |
| No, though it was long thought to be | The world's heaviest extant bony fish has long been considered the ocean sunfish Mola mola (note: was 'Not anymore', which implied the fish once held the record; the record fish was never Mola mola) |
| The title rested on a specimen weighed at about 2,300 kilograms | the world record specimen (2300 kg) was actually a misidentified giant sunfish M. alexandrini |
| a 2022 review of giant-sunfish records found that fish had been misidentified | we confirm that the world's heaviest extant bony fish specimen actually weighed was a female M. alexandrini (2300 kg, 272 cm total length) captured from Kamogawa, Chiba Prefecture, Japan, on August 16, 1996. (note: 2022 is the paper's own publication year; reflects the paper's own confirmed finding, not the earlier hedged 'suggests' sentence) |
| it was actually a giant sunfish, Mola alexandrini, a separate species caught off Japan in 1996 | captured from Kamogawa, Chiba Prefecture, Japan, on August 16, 1996 |
| The review concluded Mola alexandrini is the only living bony fish researchers could confirm above 2,000 kilograms | we conclude that M. alexandrini is the only extant bony fish species we could confirm that exceeds 2000 kg (note: 'living' restores the source's 'extant'; 'above' is the source's 'exceeds') |
| so the true ocean sunfish is a very big fish, just not the outright record-holder its old reputation claims | we confirm that the world's heaviest extant bony fish specimen actually weighed was a female M. alexandrini (note: follows from the confirmed record specimen being M. alexandrini) |

## Watanabe & Sato (2008). Functional Dorsoventral Symmetry in Relation to Lift-Based Swimming in the Ocean Sunfish Mola mola. PLoS ONE.

https://doi.org/10.1371/journal.pone.0003446

| The page says | The source says |
| :--- | :--- |
| cartilage-and-jelly fish | they are neutrally buoyant independent of depth because of their subcutaneous gelatinous tissue (note: the 'jelly' half) |
| driven by synchronized, penguin-style dorsal and anal fin strokes | they stroked their dorsal and anal fins synchronously ... to generate a lift-based thrust, as penguins do using two symmetrical flippers (note: backs stats.superpower) |
| The dorsal and anal fins do the work instead, beating side to side in sync | Lateral acceleration oscillated regularly, showing that the fish stroked their dorsal and anal fins from side-to-side |
| the way a penguin flaps both flippers together, to generate lift-based thrust rather than a drag-based push | demonstrating that the thrust was lift-based rather than drag-based. This pattern of acceleration was previously reported in penguins [7] , which flap both flippers synchronously, indicating that ocean sunfish oscillate the dorsal and anal fins synchronously |
| Tagged sunfish cruised at 0.4 to 0.7 meters per second, in the same range as salmon and marlin | sunfish indeed swam continuously with frequent vertical movements at speeds of 0.4-0.7 m s-1, which is similar to the records of other large fishes such as salmons, marlins, and pelagic sharks (note: kept at the tagged fish's scope; was 'That gets a sunfish cruising', which made the fin stroke the cause of the measured speed) |
| This is not the limp drifter its reputation suggests | Contrary to the common view that ocean sunfish are planktonic fish at the mercy of oceanic currents, the sunfish tagged in this study swam actively |
| a thick gelatinous layer under the skin made up 44 percent of the weight of one 247-kilogram fish | The proportion of the mass of the gelatinous tissue to body mass significantly increased with body size ... to 44% for a 247-kg individual (note: was 'can make up nearly half a large fish's weight', from one 247-kg individual) |
| keeping the whole fish neutrally buoyant without a swim bladder | sunfish lack a swimbladder, we found that they are neutrally buoyant independent of depth because of their subcutaneous gelatinous tissue that has low density and is incompressible |
| Actual propulsion comes from those same dorsal and anal fins beating side to side in unison, generating lift-based thrust the way a penguin's two flippers do | they stroked their dorsal and anal fins synchronously ... to generate a lift-based thrust, as penguins do using two symmetrical flippers |
| for a fish with no tail fin that swims by stroking its dorsal and anal fins side to side in sync | they stroked their dorsal and anal fins synchronously ... to generate a lift-based thrust, as penguins do using two symmetrical flippers (note: task #812, vibe.reason; 'no tail fin' is claimed elsewhere from australian-museum-mola-mola) |

## Sims et al. (2009). Long-Term GPS Tracking of Ocean Sunfish Mola mola Offers a New Direction in Fish Monitoring. PLoS ONE.

https://doi.org/10.1371/journal.pone.0007351

| The page says | The source says |
| :--- | :--- |
| one GPS-tagged fish covered an estimated 1,819 kilometers over 92 days | Sunfish 3, the largest of the fish tagged (1.0 m TL), was tracked for 92 days ... This fish covered an estimated distance of 1,819 km |

## Nakamura, Goto & Sato (2015). Ocean sunfish rewarm at the surface after deep excursions to forage for siphonophores. Journal of Animal Ecology.

https://doi.org/10.1111/1365-2656.12346

| The page says | The source says |
| :--- | :--- |
| It dives for siphonophores | Siphonophores were the most abundant prey items captured by ocean sunfish |
| Jellyfish, comb jellies and siphonophores | Siphonophores were the most abundant prey items captured by ocean sunfish (note: backs the 'siphonophores' part of stats.diet) |
| Camera tags have caught sunfish hunting siphonophores on repeated daytime dives to roughly 100 to 200 meters, in water colder than 12°C | Siphonophores were the most abundant prey items captured by ocean sunfish and were typically located at a depth of 50-200 m where the water temperature was <12 °C ... foraged mainly at 100-200 m depths during the day (note: 'colder than 12°C' is worded from the source's '<12 °C'; was 'caught adults', but the abstract gives no size or age for the tagged fish) |
| Deep dives cost heat | The body temperatures decreased during deep excursions (note: was 'Every dive costs heat'; the source says deep excursions) |
| A sunfish's body temperature drops on the way down | The body temperatures decreased during deep excursions |
| researchers found the rate of heat exchange runs 3 to 7 times greater at the surface than while cooling | the whole-body heat-transfer coefficient between sunfish and the surrounding water during warming was 3-7 times greater than that during cooling (note: 'rate of heat exchange' is plain-English for the source's 'whole-body heat-transfer coefficient'; warming happens 'during subsequent surfacing periods') |
| consistent with basking between dives to recover warmth | these results suggest that the main function of surfacing is the recovery of body temperature (note: 'consistent with' preserves the source's own hedge ('these results suggest'); reviewer cut 'rather than relax') |
| sunfish diving repeatedly to about 100 to 200 meters, into water colder than 12°C, to hunt siphonophores | Siphonophores were the most abundant prey items captured by ocean sunfish and were typically located at a depth of 50-200 m where the water temperature was <12 °C ... foraged mainly at 100-200 m depths during the day (note: 'colder than 12°C' is worded from the source's '<12 °C') |
| Each deep dive drops their body temperature | The body temperatures decreased during deep excursions |
| researchers found the rate of heat exchange runs 3 to 7 times greater once the fish is back at the surface than it did while cooling | the whole-body heat-transfer coefficient between sunfish and the surrounding water during warming was 3-7 times greater than that during cooling (note: 'rate of heat exchange' is plain-English for the source's 'whole-body heat-transfer coefficient') |
| consistent with time at the surface being how it rewarms between hunting trips | these results suggest that the main function of surfacing is the recovery of body temperature (note: 'consistent with' preserves the source's own hedge ('these results suggest'); was 'lying flat in the sun', but the source says surfacing and warm surface water) |

## Sousa et al. (2016). DNA barcoding identifies a cosmopolitan diet in the ocean sunfish. Scientific Reports.

https://doi.org/10.1038/srep28762

| The page says | The source says |
| :--- | :--- |
| smaller sunfish eat mainly crustaceans and small fish | smaller individuals feeding mainly on small crustaceans and teleost fish (note: backs stats.diet; keeps the source's 'mainly') |
| What a sunfish eats changes as it grows | we found evidence for an ontogenetic shift in the diet, with smaller individuals feeding mainly on small crustaceans and teleost fish, whereas the diet of larger fish included more cnidarian species |
| In a study of juveniles and sub-adults off southern Portugal, all 37 centimeters to 1.1 meters long | Total length of the 100 sampled individuals ranged from 0.37 to 1.10 m, corresponding to juveniles and sub-adults ... sunfish captured in the tuna set-net off southern Portugal (note: reviewer: puts the diet study at its own scope; it sampled no adults) |
| the smaller fish ate mainly small crustaceans and fish from the seabed and coastal waters | smaller individuals feeding mainly on small crustaceans and teleost fish ... smaller sunfish feed predominantly on benthic and on coastal pelagic species (note: 'from the seabed and coastal waters' is the source's 'benthic and ... coastal pelagic species') |
| while the larger ones relied on open-water prey and ate more kinds of jellyfish and their relatives | whereas the diet of larger fish included more cnidarian species ... whereas larger fish depend on pelagic prey (note: 'jellyfish and their relatives' for cnidarians; 'more kinds' for 'more cnidarian species'. Was 'larger adults ... especially siphonophores': the study sampled no adults, and siphonophores come from a different study) |

## Sawai et al. (2017). Redescription of the bump-head sunfish Mola alexandrini (Ranzani 1839), senior synonym of Mola ramsayi (Giglioli 1883), with designation of a neotype for Mola mola (Linnaeus 1758) (Tetraodontiformes: Molidae). Ichthyological Research.

https://doi.org/10.1007/s10228-017-0603-6

| The page says | The source says |
| :--- | :--- |
| These species had long been confused for each other | as these two species have long been confused |
| a 2017 taxonomic study designated a fixed reference specimen for Mola mola to sort them out | A neotype of M. mola is designated for comparison with M. alexandrini, as these two species have long been confused. (note: 2017 is the paper's own publication year) |

## Johnson & Britz (2004). Leis' conundrum: Homology of the clavus of the ocean sunfishes. 2. Ontogeny of the median fins and axial skeleton of Ranzania laevis (Teleostei, Tetraodontiformes, Molidae). Journal of Morphology.

https://doi.org/10.1002/jmor.10242

| The page says | The source says |
| :--- | :--- |
| a study tracing its development in a related sunfish found it is formed from modified elements of the dorsal and anal fins, not a leftover tail fin: the caudal fin is lost in the sunfish family | the molid clavus is unequivocally formed by modified elements of the dorsal and anal fin and that the caudal fin is lost in molids (note: the study traced the slender sunfish Ranzania laevis (title) and concluded for the family Molidae) |

## Davenport et al. (2018). The locomotor system of the ocean sunfish Mola mola (L.): role of gelatinous exoskeleton, horizontal septum, muscles and tendons. Journal of Anatomy.

https://doi.org/10.1111/joa.12842

| The page says | The source says |
| :--- | :--- |
| That gelatinous layer is roughly 90 percent water, threaded with a collagen and elastin meshwork | The capsule is gelatinous (89.8% water) with a collagen and elastin meshwork. (note: 89.8% rounded to 'roughly 90 percent') |
| it houses the muscles that drive the dorsal and anal fins | It provides two compartments, one for dorsal fin musculature and one for anal fin muscles |

## Pan et al. (2016). The genome of the largest bony fish, ocean sunfish (Mola mola), provides insights into its fast growth rate. Gigascience.

https://doi.org/10.1186/s13742-016-0144-3

| The page says | The source says |
| :--- | :--- |
| cartilage-and-jelly fish | its endoskeleton is mainly composed of cartilage (note: the 'cartilage' half; the 'jelly' half is the subcutaneous gelatinous tissue, next claim) |
| A body with no tail fin, steered by a stiff clavus rudder | its lack of a caudal fin, which is replaced by a broad and stiff lobe (note: backs 'stiff' (was 'rigid', which no source used)) |
| The skeleton is mostly cartilage | its endoskeleton is mainly composed of cartilage (note: reviewer cut the lead-in 'Most of that bulk isn't muscle or bone', which no source states) |
| Researchers studying the sunfish genome found several genes tied to growth-hormone signaling showing signs of positive selection or sped-up evolution, which the study says might explain its fast growth rate | Several sunfish genes involved in the growth hormone and insulin-like growth factor 1 (GH/IGF1) axis signalling pathway were found to be under positive selection or accelerated evolution, which might explain its fast growth rate and large body size (note: was 'under unusually strong selection', which the source does not say) |