Named after a terrestrial flower, the anemone, the sea
anemone is a group of water-dwelling, filter feeding animals
of the order Actinaria. As a cnidarian, it is closely
related to coral and jellyfish. The anemone is a (usually)
solitary polyp with stinging cells (cnidocytes) in its
tentacles. These stinging cells serve to paralyze and
capture prey, which is then moved by the tentacles to
the mouth for digestion inside a central cavity. Other
close relations to the sea anemone are the solitary, tube-dwelling
anemones and the hydras. The sea anemone has a foot which
in most species attaches itself to rocks or anchors in
the sand. Some species attach to kelp and others are free-swimming.
Although not plants and therefore incapable of photosynthesis
themselves, many sea anemones form an important symbiosis
with certain single-celled green algae species which reside
in the animals' gastrodermal cells.
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