This family was discovered in 1976 when the first specimen of the megamouth, Megachasma pelagios. was found in Hawaii. To date, no more than 10 animals have been found (9 males, 1 female). They are big sharks with a cylindrical trunk, very round head, huge, terminal mouth with a white upper lip. They have large pectoral fins and a relatively large first dorsal fin (compared to the second one). The biology of this species is poorly understood. The ninth specimen was the first one that has been found in the Atlantic. It is assumed that megamouth is a deepwater species with a sluggish lifestyle. They seem to prefer plankton but other invertebrates and even small fishes have to be considered as potential food.
Typical species of the family of "Megamouth sharks":