Ctenophore
Tentaculata
Nuda
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Ctenophores are jellyfish-like
animals commonly called "
comb jellies", "
sea gooseberries", "
sea walnuts", or "
Venus's girdles." Comb jellies are voracious marine predators on
plankton. The word ctenophore (pronounced teen-oh-for) comes from
Greek,kteno-, kteis comb + -phore, meaning "comb-bearers" via New Latin ctenophorus in the 19th century.
Ctenophores are mainly composed of inert mesoglea, which causes them to have a low rate of
metabolic activity.
Many species have
bioluminescence. The name comb jelly comes from eight "comb rows" of fused
cilia, called
ctenes, that are arranged laterally along the sides of the animal and used primarily for locomotion. The ctenes of the ctenophores gives rise to a rainbow like effect, this is caused by scattering of light due to the beating of cilia and not because of bioluminescence. The Ctenophores are
hermaphroditic, and some species can reproduce asexually. Most ctenophores have two long
tentacles, but some lack tentacles completely. The tentacles have adhesive structures called colloblasts or lasso cells. These cells burst open when prey comes in contact with the tentacle, sticky threads released from each of the colloblasts will then capture the food. Some species have their entire bodysurface covered with sticky mucus that captures prey.
There are about 100 modern
species of these marine animals. One of the most familiar genus of Ctenophore is
Mnemiopsis. Due to their soft and fragile bodies, the fossil record for comb jellies is poor. A possible Ctenophore is known from the Middle
Cambrian.
