Scolecida

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Scolecida
Arenicola marina

Arenicola marina

Systematics
Empire : Animals (Animalia)
Over trunk : Lophotrochozoa (Lophotrochozoa)
Trunk : Annelids (Annelida)
Class : Polychaete (Polychaeta)
Subclass : Scolecida
Order : Scolecida
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 :

literature

Web links

Commons : Scolecida  - collection of images, videos and audio files