Phoronid

Phoronis hippocrepia

All 15 extant species of the horseshoe worms ( Phoronida ) belonging to the two genera Phoronis and Phoronopsis who belong to the family Phoronidae.

Horseshoe worms live in tropical and subtropical seas. They live in interspersed with foreign bodies Chitinröhren, often in association with cylinder roses in marine sediments at depths up to 400 meters.

The name " horseshoe worms " refers to the characteristic U- shaped curved tentacle apparatus with which the animals filter their food. This tentacle apparatus is called a lophophore organ ( gr Lophos " head of hair " ), the lophophore is the U-shaped support on which sit the individual tentacles. A similarly structured crown of tentacles around the mouth opening is also found in the brachiopods ( Brachiopoda ) and bryozoans ( Bryozoa ), therefore these two groups often with horseshoe worms as a large group or Lophophorata Tentaculata ( ring probe) were pooled. Molecular biological relationship could this hypothesis be confirmed only partially. Horseshoe worms and brachiopods are therefore sister groups for this taxon different names such as " Brachiozoa " and " Phoronozoa " have been proposed. However, the third traditional " Lophophorata " group, the bryozoans appear to be not closely related to the other two lines.

Anatomy

List of species

• Phoronis ovalis
• Phoronis hippocrepia
• Phoronis ijimai
• Phoronis australis
• Phoronis muelleri
• Phoronis psammophila
• Phoronis pallida
• Phoronopsis albomaculata
• Phoronopsis harmeri
• Phoronopsis californica
• Phoronopsis malakhovi

See also: Classification of the animal kingdom