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.
