Brachiozoa
| Brachiozoa | ||||||||||||
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A colony of the horseshoe worm Phoronis hippocrepis in shallow water on the coast of Italy. |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Brachiozoa | ||||||||||||
| Cavalier-Smith , 1998 |
The Brachiozoa are a rankless taxon in which two tribes of marine invertebrates are united, the horseshoe worms (Phoronida) and the armpods (Brachiopoda). Both morphological and molecular genetic research shows that the two taxa are sister groups .
features
The most important common characteristic of the Brachiozoa is their tentacle apparatus (lophophor), which is created very early in the larvae. The mouth opening is between the tentacles, the anus outside, near the lophophore. Further autapomorphies are the monociliary skin cells, i. This means that each individual cell has only one cilia and paired metanephridia (excretory organs). Since the body and intestine of armpods and horseshoe worms are twisted in different ways, it is assumed that the intestines of the Brachiozoa parent species were straight. While the arm pods form shells and thus resemble the unrelated mussels , the horseshoe worms are shellless.
Internal system
Molecular biological studies indicate that the horseshoe worms are part of the armpods taxon. The possible phylogenetic relationships are illustrated by the following cladogram :
| Brachiozoa |
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The inarticulata are divided as a paraphyletic group into the linguliformea and the craniiformea .
literature
- Hynek Burda , Gero Hilken, Jan Zrzavý: Systematic Zoology. UTB, Stuttgart; : 1st edition 2008, pp. 135-140, ISBN 3825231194
Individual evidence
- ^ A. Williams, SJ Carlson, CHC Brunton, LE Holmer, L. Popov: A supra-ordinal classification of the Brachiopoda. In: Philosophical Transactions of the Royal Society of London. Series B 351 , 1996, pp. 1171-1193.