Cephalopod

related topics
{specie, animal, plant}
{math, energy, light}
{disease, patient, cell}
{ship, engine, design}
{@card@, make, design}
{language, word, form}

A cephalopod is any member of the molluscan class Cephalopoda (Greek plural Κεφαλόποδα (kephalópoda); "head-feet"). These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles (muscular hydrostats) modified from the primitive molluscan foot. Fishermen sometimes call them inkfish, referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology.

Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two, only distantly related, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by Nautilus and Allonautilus. In the Coleoidea the molluscan shell has been internalized or is absent, whereas in the Nautiloidea the external shell remains. About 800 living species of cephalopods have been identified. Two important extinct taxa are the Ammonoidea (ammonites) and Belemnoidea (belemnites).

Contents

Full article ▸

related documents
Flatworm
Eared seal
Mole
Wolverine
Australian Kelpie
Picinae
Pteranodon
Apicomplexa
Gecko
Genetic drift
Manx (cat)
Neoteny
Aardwolf
Baboon
Mouse
Possum
Koi
Akita Inu
Strepsiptera
Locust
Mesozoa
Junk DNA
British Shorthair
Diprotodontia
Xylem
Spiny lobster
Virginia Opossum
Narcissus (genus)
True owl
Magnoliaceae