A New Phylum: Cycliophora

In December of 1995, two Danish biologists reported the discovery of a strange new kind of creature, smaller than a period on a printed page, with a striking circular mouth surrounded by a ring of fine hairlike cilia. The tiny organism was so unusual that they assigned it to an entirely new phylum, Cycliophora (Greek for "carrying a small wheel"). Found adhering to the mouthparts of a lobster like a suction cup, Cycliophora apparently sucks up stray food particles as the lobster eats. There are only about 35 known animal phyla, so finding a new one is an extremely rare event! The last new phylum -- also of a microscopic marine creature -- was proposed in 1983. So far there is only one species in the phylum, given the name Symbion pandora, the first word referring to the animal's life as a symbiont, the second an allusion to its intricate life cycle. While adhering to the lobster, the tiny animal reproduced asexually from buds, but when the lobster starts to molt, the symbiont begins a bizarre form of sexual reproduction. Dwarf males emerge, with nothing but brains and reproductive organs. Each dwarf male seeks out another female symbiont on the molting lobster and fertilizes its eggs, generating free-swimming individuals that can seek out another lobster and renew the life cycle. It is this highly unusual life cycle, with both asexual and sexual stages, that has prompted the Danish scientists to propose assigning S. pandora to a unique phylum all its own.

Source: "Flyspeck on a Lobster Lip Turns Biology on Its Ear" by Natalie Angier, New York Times, December 14, 1995.

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