Opisthobranchia

Opisthobranchia

[ə‚pis·thə′braŋ·kē·ə]

(invertebrate zoology)

A subclass of the class Gastropoda containing the sea hares, sea butterflies, and sea slugs; generally characterized by having gills, a small external or internal shell, and two pairs of tentacles.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Opisthobranchia

 

a subclass of gastropod mollusks. The most primitive opisthobranches have an external shell and a muscular foot with lateral processes (parapodia). In the majority of opisthobranches the shell is overgrown by the mantle and is partially or completely reduced. The internal sac is also reduced. Complete secondary bilateral symmetry is characteristic of many opisthobranches. They are hermaphrodites. The majority of species have a swimming larva called a veliger. There are 11 orders, which include about 10,000 species. They inhabit all depths of the ocean; only a few live in fresh waters. The majority are benthonic. There are predacious and herbivorous forms.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.