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London A. Fletcher

  • Biodiversity Journal, 14 (1): 0061-0164

    Ingrid N. Visser, Marianne Nyegaard & London A. Fletcher
    Orca, Orcinus orca (Linnaeus, 1758) (Mammalia Cetacea), interactions with ocean sunfishes (Family Molidae, genus Mola Kölreuter, 1766 and Masturus Gill, 1884): A global review.
    https://doi.org/10.31396/Biodiv.Jour.2023.14.1.61.164

    ABSTRACT
    To better understand the interactions between orca, Orcinus orca (Linnaeus, 1758), killer whale (Mammalia Cetacea Delphinidae) and the large species of ocean sunfish (molids), Mola spp. and Masturus lanceolatus (Tetraodontiformes Molidae Actinopterygii), we searched for published and unpublished records of contact between these taxa. We reviewed a total of 73 interactions between 1961 and 2022, with social media in recent decades clearly facilitating dissemination of records. The interactions were primarily clustered in hotspots in Oceania (n=17), the eastern Pacific Ocean off Central and North America (n=33), and the South Atlantic off South Africa (n=10). We assessed predation risk for the molids by distinguishing between non-predation (n=29) and predation (n=42) interactions (the status of two interactions could not be established). We document what we believe to be the first confirmed predation by orca on M. alexandrini (n=3) and we reaffirm that predation occurs on M. mola and Ma. lanceolatus. Both non-predation and predation interactions involved orca who had previously been documented feeding on fish (elasmobranch and teleost) (n=9) and mammals (pinnipeds and cetaceans) (n=19). The most common orca group size was a single orca (n=27) and where molid numbers could be established (n=65), all but one interaction involved a single molid. During interactions the orca exhibited cooperative hunting and food sharing and learning/teaching may have been occurring. The relatively low number of interactions found for these two sympatric and charismatic species is surprising. Explanations may include prey-selection specificity by some orca and/or reflect the opportunistic nature of human documentation. However, our findings suggest that molids are potentially a localized food source for some orca in Oceania and the eastern Pacific, as predation was documented for 65% and 58% of interactions within those regions respectively.

  • Biodiversity Journal, 14 (1): 0019-0060

    Ingrid N. Visser & London A. Fletcher
    First records of orca, Orcinus orca (Linnaeus, 1758) (Mammalia Cetacea), predation on sharptail ocean sunfish, Masturus lanceolatus (É. Liénard, 1840) (Pisces Molidae), with novel components of foraging behaviour discovered through social media.
    https://doi.org/10.31396/Biodiv.Jour.2023.14.1.19.60

    ABSTRACT
    Foraging techniques for orca - Orcinus orca (Linnaeus, 1758), killer whale, Mammalia, Cetacea), have been documented since at least the 16th century and in the last few decades a wide range of behaviours such as ‘carousel feeding’, ‘intentional stranding’ and ‘karate-chop-ping’ have been added to the species repertoire. During a recent global review, where records were sourced primarily through social media postings, orca interactions with the large species of ocean sunfish - Mola spp. and Masturus lanceolatus (É. Liénard, 1840) (Actinopterygii, Tetraodontiformes, Family Molidae) - were collated. We discovered orca utilizing novel components of foraging strategies on these fishes. Specifically, after targeting the molids pectoral fins, the orca; (i) created a wound in the side of the molid and removed the intestines (and potentially other organs) from the still-alive molid and consumed them and (ii) then disarticulated the molid and inserted their rostrum (maxillae & mandibles) into the body cavity to extract tissue. These behaviours were documented in the South Atlantic, Oceania and the eastern Pacific Ocean, with those in the latter including what we believe to be the first confirmed predation by orca of Ma. lanceolatus. That, coupled with the novel behaviours described, may suggest an orca ecotype which has yet to be formally described, highlighting how social media can be used to document biodiversity.

  • Biodiversity Journal, 14 (1): 0003-0017

    Marianne Nyegaard, Ingrid N. Visser & London A. Fletcher
    Ocean sunfish, genus Mola Kölreuter, 1766 (Pisces Molidae), exhibit surprising levels of agility during interactions with orca, Orcinus orca (Linnaeus, 1758) (Mammalia Delphinidae)
    https://doi.org/10.31396/Biodiv.Jour.2023.14.1.3.17

    ABSTRACT
    Ocean sunfish (Mola spp.) are well known for their large adult size and peculiar morphology, which in combination give them the resemblance of a giant, swimming fish head. At first glance, this unusual body form hints at locomotive ineptitude, and traditionally molids have indeed been considered poor swimmers. Although this archaic view has been thoroughly rebutted in recent years, with studies revealing molids are strong swimmers (for example their ability to rapidly accelerate, with recorded burst speeds for Mola mola of 6.6 m/s), their fine scale maneuverability is unclear. Furthermore, many natural molid behaviours are not well understood, including antipredator behaviours, as opportunities to observe this taxa in the wild are limited. Unexpectedly, during a recent global review of molid interactions with orca (a molid predator), a number of video recordings revealed surprisingly rapid and agile molid movements. These included the molids turning up-side down, rolling backwards, pivoting and spinning. These behaviours appeared to be deliberate attempts on behalf of the molids to keep the clavus (‘tail’) towards the orca, keep the ventral area away, evade the orca, and/or discourage the orca from making physical contact. Here, we describe eight ‘Evade’ behaviours based on video analysis, present detailed descriptions and provide examples.