Megamouth Shark

The Megamouth Shark is a filter-feeding species and one of only three plankton-eating sharks, alongside the whale shark and basking shark. First discovered in 1976 off Hawaii, it remains among the most rarely encountered large sharks, with only a few hundred confirmed sightings worldwide. It is the sole member of family Megachasmidae. Adults reach roughly 4-5.5 meters. Despite its enormous size and cavernous mouth, it is completely harmless to humans, feeding exclusively on tiny planktonic organisms. Its conservation status is listed as Least Concern, though data remain sparse given how infrequently it is observed.

• Extremely large, broad, rounded head with a huge terminal mouth spanning nearly the width of the head
• Blackish-brown to gray back with a pale, silvery-white underside
• Soft, flabby body with loose skin
• Small eyes set well forward on the head
• Long, asymmetrical tail with a large upper lobe The combination of the oversized rounded mouth and soft flabby body distinguishes it instantly from other large filter feeders like the basking shark, which has a pointed snout and gill slits nearly encircling the head.

Megamouth Sharks inhabit deep tropical and warm-temperate oceanic waters, generally at depths of 120-166 meters during the day and rising to near-surface waters, around 12-25 meters, at night. This vertical migration follows the daily movement of deep scattering layer plankton, its primary food source. Confirmed records span the Pacific, Atlantic, and Indian Oceans, including Japan, the Philippines, Taiwan, California, and the Gulf of Mexico. It appears to be a pelagic, wide-ranging species rather than one tied to any coastline, though most sightings remain incidental catches or strandings.

Megamouth Sharks are slow, sluggish swimmers that filter feed by opening their huge mouths to engulf water containing plankton, straining prey through fine gill rakers before expelling the water. They undertake a daily vertical migration, following planktonic prey from deep water by day to shallower depths at night. Unlike the whale shark, which is more surface-oriented, the megamouth remains largely a mesopelagic species. Reproduction is presumed ovoviviparous, though no pregnant females or litters have ever been documented, leaving much of its life history a mystery.