| 翻訳と辞書 |
| Megamouth shark ： ウィキペディア英語版 |
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 60 specimens known to have been caught or sighted as of January 2015, 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 fossilized tooth remains.〔Shimada, K. 2007. Mesozoic origin for megamouth shark (Lamniformes: Megachasmidae). ''Journal of Vertebrate Paleontology'' 27:512–516. ((Link at BioOne) )〕〔Shimada, K., Welton, B.J., and Long, D.J. 2014. A new fossil megamouth shark (Lamniformes, Megachasmidae) from the Oligocene-Miocene of the western United States. ''Journal of Vertebrate Paleontology'' 34:281-290.〕
==Description==
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 caudal keels. The megamouth is considerably less active than the other filter-feeding sharks, the basking shark and the whale shark. The megamouth has a stout body and a long, wide bulbous head.
Megamouths are large sharks, able to grow to in length. Males mature by and females by . Weights of up to have been reported.
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. This white band is present in both sexes and is though to be used as a means of identification to other megamouth sharks. Their mouths can reach up to wide.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Megamouth shark」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|