Pterobranchia
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Pterobranchia is a clade of small, worm-shaped animals. They belong to the hemichordata, and live in secreted tubes on the ocean floor. Pterobranchia feed by filtering plankton out of the water with the help of cilia attached to tentacles. There are about 30 known living species in the group.
The class Pterobranchia was established by Ray Lankester in 1877. It contained, at that time, the single genus Rhabdopleura. Rhabdopleura was at first regarded as an aberrant Polyzoon, but with the publication of the Challenger Report (Cephalodiscus) in 1887, it became clear that Cephalodiscus, the second genus now included in the order, had affinities in the direction of the Enteropneusta.
Study under an electron microscope have suggested that pterobranchs belong to the same clade as the extinct graptolites.[1]
[edit] Footnotes
- ^ Fortey, Richard A. (1998). Life: a natural history of the first four billion years of life on earth. New York: Alfred A. Knopf, 129. ISBN 0-375-40119-9.
[edit] References
- This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
- Cameron, C. B. Classification of the extant hemichordata
- At Billie Swalla's site
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