Megamouth shark The megamouth shark (Megachasma pelagios) is an extremely rare species of deepwater shark, and the smallest of the three planktivorous sharks besides the whale shark and basking shark. Since its discovery in 1976, few megamouth sharks have been seen, with 59 specimens known to have been caught or sighted as of May 2014, including three recordings on film. Like the other two filter feeders, it swims with its enormous mouth wide open, filtering water for plankton and jellyfish. It is distinctive for its large head with rubbery lips. It is so unlike any other type of shark that it is usually considered to be the sole extant species in the distinct family Megachasmidae, though suggestion has been made that it may belong in the family Cetorhinidae, of which the basking shark is currently the sole extant member. In addition to the living M. pelagios, however, two extinct megamouth species — the Cretaceous M. comanchensis and the Oligocene-Miocene M. applegatei — have also recently been proposed on the basis of fossilised tooth remains. Physical characteristics[edit] The appearance of the megamouth is distinctive, but little else is known about it. It has a brownish-black colour on top, is white underneath, and has an asymmetrical tail with a long upper lobe, similar to that of the thresher shark. The interior of its gill slits are lined with finger-like gill rakers that capture its food. A relatively poor swimmer, the megamouth has a soft, flabby body and lacks keels. Megamouths are large sharks, able to grow to 5.5 metres (18 ft) in length. Males mature by 4 metres (13 ft) and females by 5 metres (16 ft). Weights of up to 1,215 kg (2,679 lb) have been reported. The average size of their mouth is about 1.3 meters. As their name implies, megamouths have a large mouth with small teeth, and a broad, rounded snout, causing observers to occasionally mistake megamouth for a young orca. The mouth is surrounded by luminous photophores, which may act as a lure for plankton or small fish. Their mouths can reach up to 1.3 metres wide. Behaviour[edit]
Posted on: Thu, 03 Jul 2014 04:04:40 +0000
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