Loricifera
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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.
[edit] References
Barnes, R.S.K. et al (2001) The Invertebrates: A Synthesis. Oxford: Blackwell Science. ISBN 0-632-04761-5
[edit] Further reading
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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