Definify.com
Webster 1913 Edition
Cephalopoda
‖
Cephˊa-lop′o-da
(sĕfˊȧ-lŏp′ō̍-dȧ)
, Noun.
pl.
[NL., gr. Gr.
κεφαλή
head + -poda
: cf. F. céphalopode
.] (Zool.)
The highest class of
Mollusca
. ☞ 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
.