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Megamouth Shark

The mystery shark of the deep

Order: Lamniformes

Family: Megachasmidae

Genus & Species: Megachasma pelagios


The megamouth shark's name says it all: it is a shark with a huge mouth. The head is bulbous with protruding jaws. There are white marks on the tips of the fins and mouth and a dark triangular mark on the base of the throat. The average length of the megamouth is 4.5 m (15 ft.), although a captured female was 5 m (16.6 ft) long. The average weight is 750 kg (1650 lb). The captured female weighed a whopping 1040 kg (2288 lb). The female had 55 tooth rows on the upper jaw and 75 on the lower jaw. The teeth are small and used to filter food. The body is flabby and cylindrical and the eyes are rather small. Megamouths are slow swimmers.


The megamouth shark has been spotted off the coasts of Hawaii, California, Japan, the Philippines, Senegal, Indonesia, and western Australia in the Pacific and Atlantic Oceans. It is a deep-ocean creature and comes up to the surface to feed. They have been spotted in both temperate and tropical waters of the Pacific.


The megamouth shark is a filter-feeder like the whale and basking sharks. It migrates through the water along with its prey, which is mainly shrimp and plankton. For example, at 6 pm the megamouth comes up to the surface where the shrimp swim. At 6 am it follows the shrimp back down into the depths of 150 ft of water to continue feeding.


Because the megamouth shark is somewhat of a mystery fish and is considered the rarest of all sharks, no enemies are known. Because of its size its enemies are probably very few. However, on August 30, 1998, off the coast of Indonesia, a boat with WWF Italy volunteers out looking for whales came across three sperm whales "attacking" a megamouth shark. As they approached, the whales swam off. The shark was bewildered and evidence of the assault were clearly shown along the gills and dorsal fin. Whether the sperm whales were attacking the shark, playing with it, or just curious is not known.


Little is known about its breeding habits. It breeds sexually through internal fertilization. The babies are miniature replicas of the parents. The captured female had several whitish ova measuring 5-10 mm in diameter.


The megamouth shark was not known to exist until 1976, when a male got caught in a US Navy trawler's parachute anchor off the coast of Hawaii. The discovery shocked the scientific world because before 1976 there was not even a hint as to its existence. Since 1976, 11 other megamouth sharks have been spotted, caught, or washed ashore. Only one female has been found.


The megamouth is the only known species in the family Megachasmidae. It shares the order Lamniformes along with the mackerel sharks, such as the great white and basking sharks.