Megamouth Shark

Presentation

The megamouth shark is a rare species of filter-feeding shark discovered only in 1976. It owes its name to its particularly large and rounded mouth, which is disproportionate to the rest of its body. Living in ocean depths, it is rarely observed by humans and remains one of the most poorly understood sharks. Despite its impressive size, it is completely harmless to humans because it feeds exclusively on tiny planktonic organisms. Its skin is dark colored, brownish-black on the back and lighter on the belly. Fewer than a hundred specimens have been recorded since its discovery, making it one of the rarest large marine vertebrates in the world.

The megamouth shark has a massive cylindrical body, a large rounded head, and a mouth that can open very wide. It displays flabby and soft skin, unlike the rough skin of many other sharks. Its small eyes and photophore organs around the mouth suggest an adaptation to life in deep, dimly lit waters.

Characteristics

Indicative values: they vary by subspecies, sex and region.

Habitat and distribution

The megamouth shark inhabits the deep ocean waters, generally at depths of 150 to 200 metres during the day, rising to 12 to 25 metres at night. It frequents pelagic zones far from shore, away from the seafloor. It is not associated with coastal or reef habitats.

Behaviour

It is a pelagic and solitary species, most often observed alone. It practices marked diel vertical migration, remaining in the depths during the day and rising closer to the surface at night. Its behavior remains largely unknown due to the rarity of observations and its difficult-to-access habitat.

Reproduction

The reproduction of the megamouth shark is poorly documented. By analogy with other lamniform sharks, it is presumed to be ovoviviparous, with embryos developing inside the mother. The number of young per litter and the length of gestation remain unknown due to insufficient observations.

Peculiarities

The megamouth shark was not discovered by science until 1976, off the coast of Hawaii, making it one of the latest discoveries among large sharks. Its extremely large mouth, capable of opening wide to filter water, gave it its common name. It shares the filter-feeding mode of eating with the basking shark and whale shark, although these three species are not closely related.

Threats and conservation

The exact threats facing the species are poorly known because of its rarity and deep-sea habitat. It may occasionally be caught incidentally by pelagic nets or longlines. No targeted fishing pressure has been documented to date.

References

Profile updated 07 September 2026 · Reviewed by the TunisieVet editorial team.