hydroid

a member of the COELENTERATE class Hydrozoa. Most are colonial forms which grow in the marine environment on rocks and seaweeds, such as Obelia. Usually, there is an ALTERNATION OF GENERATIONS (not in HYDRA) in which the MEDUSA (free-swimming) stage carries the sex organs. The sedentary, nonsexual stage of this life cycle is itself referred to as the POLYP or (less commonly) hydroid stage.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

Mentioned in

alternation of generations
animal kingdom
blastostyle
bryozoan, polyzoan
Cnidaria
Coelenterata
coelenterate
hydrozoan
Trachylina

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