Aeolid

Part of speech: noun, adjective

Definitions

1. A small marine mollusk characterized by numerous finger-like appendages on its back called cerata used for respiration and defense; a type of nudibranch distinguished by this distinctive anatomy; an oceanic gastropod noted for its often bright colors and unique external gills
2. An underwater creature featuring multiple elongated dorsal projections serving respiratory and protective functions; a subclass of sea slugs identified by these external appendages; a colorful shell-less sea snail inhabiting marine environments with specialized cerata for breathing
3. A sea-dwelling, shell-free gastropod possessing numerous tentacle-like cerata that aid in gas exchange and defense mechanisms; a species within nudibranchs known for vibrant appearances and external gills; a soft-bodied mollusk adapted to aquatic life with distinctive cerata structures

Etymology: The name goes back to Aeolus, the keeper of the winds in Greek myth. Naturalists gave the genus "Aeolidia" to a group of sea slugs whose branching, waving cerata seemed to suit a wind god, though the exact reason for the choice is uncertain. Those cerata are the feathery projections along the back that do much of the breathing and carry digestive gland extensions. The English word is formed from that genus name plus "-id," a suffix borrowed from Greek "-idēs," which marked descent or belonging and became standard in zoology for members of a family or group. So an aeolid is simply a member of the group named for Aeolus. Strictly, it is a sea slug, a nudibranch, not a snail.

Synonyms: nudibranch, sea slug, gastropod, marine mollusk, shell-less snail