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Cephalopoda 头足纲 头足纲 Cephalopoda n 1: octopuses; squids; cuttlefish; pearly nautilus [ synonym: { Cephalopoda}, { class Cephalopoda}] Cephalopoda \ Ceph` a* lop" o* da\ ( s[ e^] f`[. a]* l[ o^] p"[- o]* d[. a]), n. pl. [ NL., gr. Gr. kefalh` head - poda: cf. F. c[' e] phalopode.] ( Zool.) The highest class of Mollusca. [ 1913 Webster] Note: They have, around the front of the head, a group of elongated muscular arms, which are usually furnished with prehensile suckers or hooks. The head is highly developed, with large, well organized eyes and ears, and usually with a cartilaginous brain case. The higher forms, as the cuttlefishes, squids, and octopi, swim rapidly by ejecting a jet of water from the tubular siphon beneath the head. They have a pair of powerful horny jaws shaped like a parrot' s beak, and a bag of inklike fluid which they can eject from the siphon, thus clouding the water in order to escape from their enemies. They are divided into two orders, the { Dibranchiata}, having two gills and eight or ten sucker- bearing arms, and the { Tetrabranchiata}, with four gills and numerous arms without suckers. The latter are all extinct except the { Nautilus}. See { Octopus}, { Squid}, { Nautilus}. [ 1913 Webster] Cephalopodic
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