Megamouth shark
| Megamouth shark | ||||||||||||||
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| Megachasma pelagios |
The megamouth shark Megachasma pelagios is an extremely rare and unusual species of shark, first seen in 1976, with 17 specimens having been found as of 2003. Like the basking shark and whale shark, it is a filter feeder, consuming plankton and jellyfish, and is distinctive for its large head with rubbery lips. It is so unlike any other type of shark that it is classified in its own family Megachasmidae.
The first megamouth was captured on November 15, 1976 off Oahu when it attempted to swallow the sea anchor of a US Navy ship. Examination of the 4.5 m (14.6 ft), 750 kg (1,650 lb) specimen by Leighton Taylor showed it to be an entirely unknown type of shark, rivaling the coelacanth as the most sensational discovery in ichthyology during the 20th century.
Since then, several more have been collected in various parts of the world, with the most (five) in the vicinity of Japan. On October 21 1990, Megamouth #6 was found entangled in a drift gillnet off Dana Point, California, taken alive, and then released after tracking devices were attached; it was observed to move close to the surface at night and deeper during the day. The carcass of Megamouth #7 was found in 1994 in Japan and put on display at Marine World Umino-Nakamichi.
The appearance of the megamouth is unmistakable. It has a large mouth with small teeth, and a broad rounded snout - observers have mistaken it for a young orca - a generally brownish-blackish color on top and white underneath, and an asymmetrical tail with a long upper lobe, similar to the thresher shark. The interior of its gill slits are lined with finger-like gill rakers that capture its food.
