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Class: Anthozoa
 Range
and Habitat: Anemones are found in coastal areas all over
the world, especiallyin warmer waters. They are found both in
shallow and deeper water. They attach themselves to shells, rocks,
timber, or whatever submerged substrata they can find, by their
pedal discs. Some burrow.
Description: They range in size from less than a 1.25
cm (.5 in) to nearly 1.8 m (6 ft) in diameter. They are cylindrical
in form with a crown of tentacles arranged in one or more circles
around the mouth. The stalk ends with a smooth muscular basal
disc on which the anemone can slide about very slowly.
 Habits
and Adaptations: On the tentacles are stinging cells or nematocysts.
A nematocyst is a small capsule with a thread-like tube coiled
inside. When a trigger bristle is disturbed, the coiled tube shoots
out and imbeds in whatever triggered it. There is a minute amount
of poison injected. The nematocysts are used both for defense
and capturing food.
Diet: Carnivorous, feeding on fish or almost any live
animals of suitable size. Some species live on minute forms caught
by ciliary currents.
 Breeding
and Maturation: The sexes are separate. The eggs or sperm
are ejected through the mouth. The fertilized egg develops into
a planula, which finally settles down somewhere and grows into
a single anemone. Asexually they reproduce by pulling apart into
2 halves, or, in some species, small pieces of the pedal disc
break off and regenerate into a small anemone.
Miscellaneous: Anemones form some interesting mutualistic
relationships with other organisms. Many anemones house unicellular
algae in their tissues from which they undoubtedly derive some
nutrients. Some hermit crabs place anemones on the snail shells
in which the crabs live, gaining some protection from the presence
of the anemone, while the anemone dines on particles of food dropped
by the crab. The clownfish form associations with large anemones.
Somehow, these fish do not trigger discharge of the anemone's
nematocysts, but if some other fish is so unfortunate as to brush
the anemone's tentacles, it is likely to become a meal.
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