A review of giants: Examining the species identities of the world's heaviest extant bony fishes (ocean sunfishes, family <scp>Molidae</scp>)

Sawai, Etsuro; Nyegaard, Marianne

doi:10.1111/jfb.15039

Cited by 6 publications

(9 citation statements)

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“…The M. alexandrini reported here is the heaviest extant teleost specimen reported to date. It exceeds by nearly half a ton (444 kg) the largest previously known specimen (2300 kg), caught off Kamogawa, Japan in 1996 (Guinness World Records, 2019; Sawai & Nyegaard, 2022). The giant sunfish M. alexandrini can thus reach more than twice the maximum weight of its congeneric, the ocean sunfish M. mola (heaviest record 1320 kg; Kawakami et al ., 2008; Yamanoue et al ., 2010; Sawai et al ., 2020).…”

Section: Figurementioning

confidence: 99%

“…Unravelling animal extreme sizes brings new insights into species physiology and its role in ecosystems (Gaines & Denny, 1993; Goldbogen et al ., 2011). The round ocean sunfishes comprise the heaviest extant bony fishes, attaining more than 3 m in total length (TL) and over 2000 kg (Pope et al ., 2010; Sawai & Nyegaard, 2022), making them one of the most emblematic fishes in the ocean. The genus is ubiquitous in temperate and tropical seas, and is composed of three species: the ocean sunfish Mola mola (Linnaeus, 1758), the giant sunfish Mola alexandrini (Ranzani, 1839) and the hoodwinker sunfish Mola tecta Nyegaard et al ., 2017 (Caldera et al ., 2020; Sawai et al ., 2020).…”

Section: Figurementioning

confidence: 99%

“…M. alexandrini and M. tecta have a long history of being confused with M. mola, and the taxonomy was only recently clarified (Nyegaard et al, 2018;Sawai et al, 2018). To date, the heaviest reported sunfish was a female M. alexandrini (2300 kg, 272 cm TL) captured from Kamogawa, Chiba Prefecture, Japan, on 16 August 1996(Guinness World Records, 2019Sawai et al, 2020;Sawai & Nyegaard, 2022). However, in December 2021, a Mola specimen was recorded in the oceanic archipelago of the Azores, in the mid-north-east Atlantic, greatly exceeding the weight of the Kamogawa sunfish.…”

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confidence: 99%

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The heaviest bony fish in the world: A 2744‐kg giant sunfish Mola alexandrini (Ranzani, 1839) from the North Atlantic

Gomes‐Pereira

Pham

Miodonski³

et al. 2022

Journal of Fish Biology

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Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

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confidence: 99%

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The heaviest bony fish in the world: A 2744‐kg giant sunfish Mola alexandrini (Ranzani, 1839) from the North Atlantic

Gomes‐Pereira

Pham

Miodonski³

et al. 2022

Journal of Fish Biology

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“…However, given the large size spectrum of Mola spp., it is possible that new patterns could potentially develop with growth, akin to Turing's reaction-diffusion model (Turing, 1952) of pattern formation in biological systems (for examples in teleosts see Kondo and Asai, 1995;Rosenthal and Marshall, 2011;Delcourt et al, 2018). This is particularly pertinent for M. alexandrini due to the large growth spectrum and changes in morphology with size (Sawai et al, 2017;Sawai et al, 2018;Gomes-Pereira et al, 2022;Sawai and Nyegaard, 2022). Most notably, M. alexandrini develops a large head bump, a large chin bump, and bulging lateral ridges with growth, and as for all Mola species, the dorsal and anal fins become shorter and broader relative to fish length (Watanabe and Sato, 2008;Phillips et al, 2018;Sawai et al, 2018) (Figure 3).…”

Section: Pattern Stabilitymentioning

confidence: 99%

“…The method has also been applied to teleosts (e.g., Giglio et al, 2014;Chaves et al, 2016;Couffer, 2017;Mucientes et al, 2019;Pedersen and Mohammed, 2021;Sèbe, 2021), but has to date not been applied to the ocean sunfishes ('molids'). The family comprises five species (Fricke et al, 2022), including the world's heaviest bony fish, giant sunfish Mola alexandrini (Ranzani, 1839) sensu (Sawai et al, 2018), capable of reaching at least 2.7 ton in body weight and at least 3.3 m in total length (TL) (Gomes-Pereira et al, 2022;Sawai and Nyegaard, 2022).…”

Section: Introductionmentioning

confidence: 99%

Rapid physiological colouration change is a challenge - but not a hindrance - to successful photo identification of giant sunfish (Mola alexandrini, Molidae)

Nyegaard,

Karmy,

McBride

et al. 2023

Front. Mar. Sci.

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Photo ID is a common tool in ecology, but has not previously been attempted for the ocean sunfishes (Mola spp., Molidae; ‘molids’). The technique, based on body patterns, could potentially be informative for studying the seasonal occurrence of giant sunfish (Mola alexandrini) on the Bali reefs (Indonesia), where this species is an important drawcard for the local SCUBA diving tourism. However, molids are capable of rapid physiological colouration change, which may complicate the application of the method. Our study aimed to determine if photo ID is nevertheless achievable and informative. To test this, we created the citizen-science platform ‘Match My Mola’ for crowd-sourcing imagery (photos and video) of M. alexandrini in Bali, and undertook trial matching (n=1,098 submissions). The submitted imagery revealed a wide range of pattern clarity, from fish with no pattern to bold displays. Video confirmed physiological colouration change can occur in seconds in this species from low to high contrast, and cause individuals to look very different between moments. However, individual patterns appear to be stable although at least some parts can become inconspicuous during low contrast displays. Despite of this, photo ID is possible, including in some instances, where only partial patterns are visible on one image compared with another. However, true negatives (confirming two fish are not the same) can be challenging. Most identified matches were of fish photographed by different divers on the same day. Only a small number (n=9) were found with resighting durations ≥1 day (1 – 2,652 days). These matches demonstrate that at least some individuals return to the same reefs both within and between seasons, with the resighting duration of 7.2 years constituting the longest known example of molid site fidelity. Comparing body morphology between resightings of > 1 year (n=6) revealed limited indications of growth, contradicting the current understanding of rapid growth in captive molids (Mola mola), and highlighting the knowledge gap regarding growth in the wild. Continued photo ID in the Bali area could provide valuable complementary information to future growth studies using other methods as well as provide further insights into molid site fidelity.

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Response to Britz (2022) regarding the validity of the giant sunfish Mola alexandrini (Ranzani, 1834) (Teleostei: Molidae)

SAWAI,

NYEGAARD

2023

Zootaxa

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The small family of ocean sunfishes has a long and complicated taxonomic and nomenclatorial history dating back several centuries. Most recently, Britz (2022) questioned the validity of Mola alexandrini (Ranzani, 1839) as the valid name for Mola sp. A sensu Yoshita et al. (2009). Specifically, he questioned the authenticity of the purported Orthragoriscus alexandrini holotype rediscovered by Sawai et al. (2018) due to uncertainties regarding the original units of measurement, along with discrepancies between the original illustration and the purported holotype. He also questioned the reliability of the illustration to reflect the fresh morphology, and the adequacy of the species description (sans illustration and holotype) to link it to any of the currently recognized Mola species. In summary, Britz (2022) opined that M. alexandrini is a species inquirenda. Here we respond to Britz’s concerns with the findings from an additional literature review. Firstly, the original species description appears to give measurements in ‘Parisian units’, yielding a discrepancy in length with the purported holotype within human error. However, due to various uncertainties, length does not appear to be a robust piece of evidence to neither confirm nor refute the specimen’s authenticity. Secondly, the morphological differences between the original illustration and the purported holotype were found to be within the expected level of accuracy for Mola illustrations at the time, by both Ranzani and others. Thirdly, a contemporaneous publication describes how Ranzani himself bought the specimen which became the Or. alexandrini holotype, suggesting he would likely have seen it in its fresh state, rendering it unlikely he would have produced a species description and illustration incongruent with this. Fourthly, re-examining the original species description suggests this provides adequate and sufficient information to link Or. alexandrini to Mola sp. A, even in the absence of a holotype. Finally, during this review, we came upon an even older paper describing Or. alexandrini, and we conclude that the currently valid name for Mola sp. A sensu Yoshita et al. (2009) is Mola alexandrini (Ranzani, 1834).

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A review of giants: Examining the species identities of the world's heaviest extant bony fishes (ocean sunfishes, family Molidae)

Cited by 6 publications

References 65 publications

The heaviest bony fish in the world: A 2744‐kg giant sunfish Mola alexandrini (Ranzani, 1839) from the North Atlantic

The heaviest bony fish in the world: A 2744‐kg giant sunfish Mola alexandrini (Ranzani, 1839) from the North Atlantic

Rapid physiological colouration change is a challenge - but not a hindrance - to successful photo identification of giant sunfish (Mola alexandrini, Molidae)

Response to Britz (2022) regarding the validity of the giant sunfish Mola alexandrini (Ranzani, 1834) (Teleostei: Molidae)

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