Sea Anemones and Other Cnidarians
Sea anemones and other benthic cnidarians are sessile animals, which mostly require hard substrates such as shells or rocks to settle on, although some may burrow in the sediment. Anemones are most diverse in the tropics, but are regularly found in the Arctic , in particular on the continental shelves. Other cnidarians found in the Arctic include sea pens (Pennatulacea), tube anemones (Ceriantharia) and benthic stages of true jellyfish. Over 200 species of cnidarians are known from Arctic waters to date, many of which are benthic or have a benthic life stage.
The columnar body of a sea anemone has a mouth in its center that is surrounded by tentacles used to collect food. Food particles end up in a stomach-like cavity that fills out most of the body and is partitioned by septa. Like other cnidarians, anemones have nematocysts, cells which are used to paralyze their prey consisting of various invertebrates and sometimes even fish. Unlike some other cnidarians, anemones lack a medusa (jelly fish) stage.
Page Author: Russ Hopcroft
Created: Oct 24, 2008