About the Rainbow Jellyfish

The rainbow jellyfish is not a true jellyfish. True jellyfish and their relatives belong to the phylum Cnidaria, while the rainbow "jellyfish" belongs to the phylum Ctenophora. Ctenophores go by many names, including comb jellies, sea walnuts and Venus's girdles. They superficially resemble jellyfish, but have slightly more complicated tissues and lack stinging cells. Their evolutionary relationship to other groups of animals is poorly understood.

The rainbow jellyfish does not quite glow, though some ctenophores do. Instead, it refracts light like a prism, creating a rainbow-like effect that makes it appear to be glowing. Specifically, the cilia, tiny hairlike structures, flicker as they move. The rainbow jellyfish uses these structures to move itself through water. It is about 5 inches long.

The rainbow jellyfish was discovered in March of 2009. Its discoverer, Lisa Gershwin, is a jellyfish expert. She made the find near the island of Tasmania. It is the 159th species that Gershwin has discovered near Australia. Gershwin speculated that the rainbow jellyfish had gone undetected for so long because it is extremely fragile and difficult to capture without destroying it.

Much about the rainbow jellyfish is presumed from a general understanding of ctenophores. Almost all ctenophores prey on plankton, and many find themselves prey to larger animals. All ctenophores are hermaphrodites, or organisms that are both male and female. A few oddball Ctenophores crawl across the bottom of the ocean, but most drift through the current, swimming weakly with their cilia. Ctenophores have slightly more complex biology than jellyfish. For example, their digestive tract is one-way, unlike the blind gut of cnidarians. They also appear to have an underlying bilateral symmetry, while all cnidarians have a radial symmetry.