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''Nautilus belauensis'', also known as the Palau nautilus, is a species of nautilus native to the waters around the Pacific island nation of Palau.〔Saunders, W.B. 1981. A new species of ''Nautilus'' from Palau. ''Veliger'' 24(1): 1–7.〕 ''N. belauensis'' is very similar to ''Nautilus pompilius'' and shares with this species a closed umbilicus covered with a callus. It differs on the basis of a modified radula and fine raised ridges across and along the shell, which form a cross-grid texture. ''N. belauensis'' is the second-largest nautilus after the giant form of ''N. pompilius pompilius''. The shell is usually up to around 210 mm in diameter, although specimens up to 226 mm have been recorded.〔Jereb, P. 2005. Family Nautilidae. ''In'': P. Jereb & C.F.E. Roper, eds. ''Cephalopods of the world. An annotated and Illustrated catalogue of species known to date. Volume 1. Chambered nautiluses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae)''. FAO Species Catalogue for Fishery Purposes. No. 4, Vol. 1. Rome, FAO. pp. 51–55. 〕 Image:Nautilus front.jpg|''N. belauensis'' seen from the front, showing the hyponome Image:Nautilus from above.jpg|Palau nautilus viewed from above Image:Diver and nautilus.jpg|Diver with Palau nautilus showing size of a typical captured specimen File:Nautilus eye, Palau.jpg|Close-up view of the eye of the Palau nautilus Image:Nautilus side.jpg|View of a Palau nautilus from the side File:Nautilus cage Palau, Micronesia.jpg|A cage used to capture Palau nautiluses from a depth of approximately 30 m: note the five nautiluses and the mostly eaten chicken. The animals are released unharmed. ==References== * Norman, M. 2000. ''Cephalopods: A World Guide''. Hackenheim, ConchBooks, p. 22. 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「Nautilus belauensis」の詳細全文を読む スポンサード リンク
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