Green Wednesday - Comb Jellyfish!

on 15 Jan 2013 

Comb Jellyfish!

The Ctenophora, commonly known as comb jellies, are a phylum of animals that live in marine waters worldwide. Their most distinctive feature is the "combs", groups of cilia they use for swimming, and they are the largest animals that swim by means of cilia – adults of various species range from a few millimeters to 1.5 meters (59 in) in size. Like cnidarians, their bodies consist of a mass of jelly, with one layer of cells on the outside and another lining the internal cavity.

Most species are hermaphrodites, in other words a single animal can produce both eggs and sperm; if they are both produced at the same time, the animal is a simultaneous hermaphrodite, and if the eggs and sperm mature at different times, the animal is a sequential hermaphrodite.  (The Sequential Hermaphrodites would be a good name for a band – Liz)

Ctenophores may be abundant during the summer months in some coastal locations, but in other places they are uncommon and difficult to find. In bays where they occur in very high numbers, predation by ctenophores may control the populations of small zooplanktonic organisms such as copepods, which might otherwise wipe out the phytoplankton (planktonic plants), which are a vital part of marine food chains.

The comb rows of most planktonic ctenophores produce a rainbow effect, which is not caused by bioluminescence but by the scattering of light as the combs move. Most species are also bioluminescent, but the light is usually blue or green and can only be seen in darkness.

Despite their soft, gelatinous bodies, fossils thought to represent ctenophores, apparently with no tentacles but many more comb-rows than modern forms, have been found in lagerstätten as far back as the early Cambrian, about 525 million years ago.

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