Scolecida
Scolecida | ||||||||||||
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Systematics | ||||||||||||
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Scientific name of the subclass | ||||||||||||
Scolecida | ||||||||||||
Rouse & Fauchald , 1997 | ||||||||||||
Scientific name of the order | ||||||||||||
Scolecida | ||||||||||||
Huxley , 1864 |
Scolecida (from ancient Greek σκώληξ scolex "worm" and εἶδος eîdos "type, form") is the name of an order while a subclass of wild and often grave forming in the sediment, as detritus or substrate eaters living polychaete (Polychaeta), the world in seas can be found.
features
The Scolecida are characterized by the fact that on their pygidium there are two pairs, sometimes even more pairs, of cirrus , while with other polygons there is at most one pair. In contrast to its sister group, the palpata , there are neither antennae nor palps at the head end of the Scolecida. The Paraonidae , which have a single central antenna , are an exception . In the Scolecida, the prostomium is clearly separated and mostly conical; only in the Scalibregmatidae does it have a T-shaped tip. In some families there are species with tiny eye spots; the rest of the species are blind. The Scolecida have parapodia with uniform ramifications. The esophagus can be turned out and thus forms a sac-like proboscis that can have several finger-like lobes. The anterior segments and their appendages are very similar to each other. Unbranched , capillary-like bristles , sometimes with hooks, sit on the notopodia and neuropodia . In some families there are simple unbranched gills on the segments , and in the family Cossuridae it is a single central pair of gills on an anterior segment.
Distribution, habitat and way of life
The Scolecida are widespread in seas around the world and live predominantly on sandy or muddy subsoil. They feed on detritus as free-living, burrowing or crawling annelids in the soft sediment , which they swallow with their evertable proboscis . As a substrate eater, they often take up the entire substrate, but only digest the organic components and excrete the mineral particles, much like earthworms do.
Systematics
The order and at the same time subclass Scolecida forms the class Polychaeta according to the systematics according to Rouse & Fauchald from 1998 with its sister group Palpata .
According to this system, the following families belong to the order Scolecida :
- Arenicolidae
- Maldanidae
- Capitellidae
- Opheliidae
- Scalibregmatidae
- Orbiniidae
- Paraonidae
- Questidae
- Cossuridae
literature
- Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Class Polychaeta. Pp. 80f., Scolecida.
- Gregory W. Rouse, Kristian Fauchald (1998): Recent views on the status, delineation, and classification of the Annelida. (PDF). American Zoologist. 38 (6), pp. 953-964. doi: 10.1093 / icb / 38.6.953
- Peter Ax: The system of Metazoa II. A textbook on phylogenetic systematics. Gustav Fischer Verlag, Stuttgart / Jena 1999. pp. 47-56, chapter Polychaeta : Scolecida , pp. 49f.
Web links
- Fredrik Pleijel and Gregory W. Rouse: Scolecida. In: The Tree of Life Web Project, 2004.
- G. Read: Polychaeta: Scolecida. Annelida.net, July 21, 2003.