The megamouth shark (Megachasma pelagios) is an elusive deep‑sea filter‑feeding shark first identified in 1976 and remains one of the ocean’s rarest and least understood large species
Discovery and rarity
The first confirmed megamouth was brought to scientists in 1976, making it a relatively recent addition to modern ichthyology. Sightings and specimens remain uncommon, so our knowledge of its biology and population status is limited.
Filter feeding and behaviour
Like whale sharks and basking sharks, the megamouth feeds by filtering plankton, small fish and jellyfish through its wide mouth while swimming slowly. Its large oral cavity and gill rakers are adapted for this passive feeding style.
Anatomy and appearance
Megamouths have a soft, flabby body, broad head and huge, rounded mouth lined with many small teeth. Their dark dorsal coloration and lighter underside, plus subtle bioluminescent photophores in the mouth region, suit a deep‑water, low‑light lifestyle.
Habitat and distribution
They inhabit deep and open ocean waters in tropical and temperate regions worldwide and often perform vertical migrations, coming nearer the surface at night to feed. Because encounters are rare, precise distribution and abundance estimates remain uncertain.
Conservation and research needs
Due to limited observations, megamouth sharks are challenging to study and monitor. Threats include bycatch and ship interactions, so continued reporting, targeted surveys and noninvasive technologies are important for understanding their ecology and informing conservation.
Takeaway
Discovered only in 1976, the megamouth shark is a rare, deep‑dwelling filter feeder whose elusive nature makes it both mysterious and scientifically valuable, highlighting how much remains to be learned about life in the open ocean.