|Various examples of sea anemones| Sea anemones are a group of
water-dwelling, predatory animals of the order Actiniaria. They
are named for the anemone, a terrestrial flower. Sea anemones
are classified in the phylum Cnidaria, class Anthozoa, subclass
Zoantharia. Anthozoa often have large polyps that allow for
digestion of larger prey and also lack a medusa stage. As
cnidarians, sea anemones are related to corals, jellyfish, tube-
dwelling anemones, and Hydra. A sea anemone is a polyp attached
at the bottom to the surface beneath it by an adhesive foot,
called a basal disc, with a column shaped body ending in an oral
disc. Most are from 1.8 to 3 centimetres (0.71 to 1.2 in) in
diameter, but anemones as small as 4 millimetres (0.16 in) or as
large as nearly 2 metres (6.6 ft) are known. They can have
anywhere from a few tens to a few hundred tentacles. The mouth,
also the anus of the sea anemone, is in the middle of the oral
disc surrounded by tentacles armed with many cnidocytes, which
are cells that function