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Chaetopterus variopedatus : ウィキペディア英語版 | Chaetopterus variopedatus
''Chaetopterus variopedatus'' is a species of parchment worm, a marine polychaete in the family Chaetopteridae. It is found worldwide. However, recent discoveries from molecular phylogeny analysis show that ''Chaetopterus variopedatus ''sensu Hartman (1959) is not a single species. Polychaetes, or marine bristle worms, have elongated bodies divided into many segments. Each segment may bear setae (bristles) and parapodia (paddle-like appendages). Some species live freely, either swimming, crawling or burrowing, and these are known as "errant". Others live permanently in tubes, either calcareous or parchment-like, and these are known as "sedentary". ==Description==
''C. variopedatus'' builds and lives permanently in a tough, flexible, papery U-shaped tube buried in soft substrate with both ends protruding like little chimneys. The worm itself is segmented, pale coloured and up to twenty-five centimetres long. The anterior end is short and has bristle-bearing segments and a shovel-like mouth.〔(Encyclopedia of Life )〕 The middle section bears parapodia. On the 12th segment these are modified into long wing-like structures which secrete mucus and form a bag. The parapodia on segments 13, 14 and 15 are fused into three paddle-shaped, piston-like structures, the purpose of which is to pump water through the tube. The water is drawn in through the anterior end and expelled through the posterior end,〔 passing through the fine mesh of the mucus bag where food particles get trapped. The mucus bag is later rolled up and passed by a conveyor belt of whipping hairs in the ciliated dorsal groove 〔(Invasion of the parchment worm )〕 to the mouth where it is swallowed whole.〔(Marine organisms database )〕 The posterior half of the worm is segmented and tapers towards the rear, bearing appendages on each segment.〔(Marine Life Information Network )〕
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