Megamouth Shark

IUCN

Scientific Name：Megachasma pelagios

Basic Information

Scientific classification

name：Megamouth Shark
Scientific Name：Megachasma pelagios
Outline：Large Fish
Family：Megachasmidae Megachasma

Vital signs

length：4–5.5 m common; max ~7 m
Weight：Approx. 750–1500 kg (est.)
lifetime：Est. 30–50 years

Feature

Rare large planktivore; huge mouth & thick lips; likely diel vertical migrations; discovered in 1976.

Distribution and Habitat

Warm outer‑shelf/slope waters worldwide (tropical–subtropical), epipelagic–mesopelagic.

Appearance

Brown‑grey to dark dorsum, pale belly; very large mouth; two spineless dorsal fins; slow swimmer.

Details

The megamouth shark (Megachasma pelagios) is a rare, filter‑feeding large shark in the familyMegachasmidae, formally described in 1976. It inhabits the epipelagic–mesopelagic zone and likely performsdiel vertical migrations to follow zooplankton.

Ecology & Reproduction

Feeds on copepods and euphausiids by slow ram‑filtering. Reproduction presumed aplacental viviparous with small litters; life‑history data remain limited.

Identification

Common length 4–5.5 m (max ~7 m); huge mouth with thick, rubbery lips; short blunt snout; brown‑grey to dark dorsum and pale underside; two spineless dorsal fins. Pale mouth lining may include faint luminescent/reflective tissue (hypothesized).

Range & Habitat

Warm‑water outer‑shelf and slope waters worldwide, especially in tropical–subtropical regions; many reports from the W Pacific/SE Asia and the E Pacific.

Threats & Conservation

Bycatch in gillnets/longlines; occasional display/use.
Knowledge gaps complicate management.
Potential nearshore disturbance from lights/vessels at night (hypothesized).

IUCN: Least Concern (LC). Priorities: standardized documentation & rapid release, minimal‑impact sampling, mitigation near coasts, and citizen‑science reporting.