actinozoa

Century Dictionary and Cyclopedia

1. A class of Cælenterata; radiated, marine zoöphytes, embracing the sea-anemones, corals, sea-pens, etc., in which the mouth is furnished with hollow retractile tentacles, simple in one subclass (Zoantharia) or fringed in the other (Alcyonaria). The digestive cavity is separated from the body-wall by an intervening perivisceral space, which is radially divided into several compartments by partitions called mesenteries, in which the reproductive organs are situated. The great majority are compound, living in a polypidom; some adhere to rocks, etc., and some are free. The rayed tentacles about the mouth present in some genera, as Actinia, no remote resemblance to some of the finest composite flowers. Reproduction is effected by eggs thrown out at the mouth, by gemmules or buds developed on the base of their disk, and by division, each separated part becoming a complete animal. They present the phenomenon known as metagenesis or alternation of generation. When reproduced by ordinary generation, the egg develops into a free locomotive planula with vibratile cilia. The sexes are either united or distinct. The Actinozoa and Hydrozoa constitute the subkingdom Cælenterata. Also called Actinoida. See Hydrozoa.

Wiktionary

1. n. Plural form of actinozoon.

GNU Webster's 1913

1. n. (Zoöl.) A group of Cœlenterata, comprising the Anthozoa and Ctenophora. The sea anemone, or actinia, is a familiar example.

WordNet 3.0

1. n. a large class of sedentary marine coelenterates that includes sea anemones and corals; the medusoid phase is entirely suppressed