Megachasma pelagios Taylor, Compagno & Struhsaker, 1983
Megamouth shark
photo by Carvalho Filho, A.

Family:  Megachasmidae (Megamouth sharks)
Max. size:  549 cm TL (male/unsexed); 709 cm TL (female)
Environment:  pelagic-oceanic; marine; depth range 5 - 600 m, oceanodromous
Distribution:  Pacific Ocean: Japan, Indonesia, Philippines, Hawaii and California, USA. Atlantic Ocean: Brazil and Senegal.
Diagnosis:  Dorsal spines (total): 0-0; Vertebrae: 125. Body stout, tapering posteriorly (Ref. 6871), tadpole-like with larger head and tapering trunk and tail (Ref. 47786). Snout extremely short but broadly rounded (Ref 43278, 47786). Head huge, blubbery (Ref. 6871). Mouth very broad and terminal on head, with corner extending behind the eyes (Ref. 6871, 43278). Jaws huge, protrusible anteriorly but not greatly distensible laterally (Ref. 43278, 47786), lower jaw extending to snout tip (Ref. 6871). Teeth very small, numerous, hooked (Ref. 43278, 6871, 47787). Gill slits moderately long, not reaching dorsal surface of head (Ref. 6871; 43278), internal gill slits lined with dense rows of papillose gill rakers (Ref. 43278). Eyes semicircular (Ref. 47786), with no nictitating membrane (Ref. 43278, 6871, 47786). Two dorsal fins, relatively low and angular; small anal fin; long, narrow pectoral fins; moderate-sized pelvic fin; caudal fin asymmetrical, non-lunate, with a short and strong ventral lobe; upper pre-caudal pit only; caudal peduncle without keels or ridges (Ref, 6871, 43278).
Biology:  Oceanic, possibly occurring in depths between 150 and 1,000 m (Ref. 6871). Epi- and mesopelagic (Ref. 58302). Feeds on planktivorous prey such as euphausiid shrimps, copepods and jellyfish (Ref. 6871). May also eat small midwater fishes. Ovoviviparous (Ref. 50449). Possibly less active than the basking and whale sharks (Ref. 6871). Its feeding habits and habitat suggest that it may be a rare catch in the future. Ovoviviparous, embryos feeding on yolk sac and other ova produced by the mother (Ref. 50449). Males mature by 400 cm (Ref. 6871). A bright white band on the snout just above the upper jaw may play a role in feeding behavior or with recognition of individuals (Ref. 47761). Preyed on by the semi-parasitic cookiecutter shark, Isistius brasiliensis.
IUCN Red List Status: Least Concern (LC); Date assessed: 09 November 2018 Ref. (130435)
Threat to humans:  Harmless
Country info:  Photographed from captured specimen from Cagayan de Oro, 21 February 1998 and 06 January 2003; by-catch in gillnet fishery; stranded specimen on the beach of Barangay Namocon in Tigbauan, Iloilo (Ref. 47737). Also Ref. 43278.


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