pycnogonida

from The Century Dictionary.

• A group of marine arthropod articulate animals, combining some characters of both Crustacea and Arachnida with others of neither of these classes; the sea-spiders.

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Zoöl.) A class of marine arthropods in which the body is small and thin, and the eight legs usually very long; -- called also Pantopoda.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun sea spiders