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Loricifera
From Wikipedia, the free encyclopedia
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 Pliciloricus enigmatus
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Nanaloricus |
Loricifera is a small phylum of marine sediment-dwelling animals with about twenty-one known species in six genera. The phylum was first described in 1983 by Reinhardt Kristensen.
Loriciferans are not yet well-studied, the entire phylum having been known to science for fewer than 25 years. They are generally less than 0.4 millimeters in length. The body of a loriciferan has three basic parts: an anterior head, a neck region, and a trunk encased in a lorica of protective plates. The anterior region is studded with spines called scalids, and it bears a mouth cone covered in stylets. This anterior part is attached to a segmented neck with which the animal can pull the head into the lorica-encased trunk region. The trunk may be covered in spines as well as hardened plates.
The animals have a muscular gut with salivary glands and a pumping mechanism that draws nutrients in. There is no circulatory system and no endocrine system, but there is a brain and ventral nerve cord. The body cavity is a pseudocoel with a mouth and an anus. The animals are divided into male and female individuals and are probably oviparous. They have a distinct larval stage. They have no fossil record.
Their closest relatives are thought to be the Kinorhyncha and Priapulida with which they constitute the taxon Scalidophora.
Barnes, R.S.K. et al (2001) The Invertebrates: A Synthesis. Oxford: Blackwell Science. ISBN 0-632-04761-5
Kristensen, R. M., (1983). Loricifera, a new phylum with aschelminthes characters from the meiobenthos. Journal for Zoological Systematics and Evolution. 21: 163-180 (in which Loricifera is first described)
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