Flabelligeridae

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Flabelligeridae
Diplocirrus incognitus

Diplocirrus incognitus

Systematics
Trunk : Annelids (Annelida)
Class : Polychaete (Polychaeta)
Subclass : Palpata
Order : Canalipalpata
Subordination : Terebellida
Family : Flabelligeridae
Scientific name
Flabelligeridae
de Saint-Joseph , 1894

Flabelligeridae is the name of a family of mostly small, in soft sediments free crawling or in burrows living polychaete (Polychaeta) in seas worldwide as detritus can be found.

features

The Flabelligeridae have a short body with few segments . They have an indistinct head with buccal tentacles that are at rest withdrawn into a membrane sheath . The front segments often have elongated, forward-facing bristles , which in this way form a head cage. The parapodia are two-branched but barely developed, and the bristles arise directly from the body wall. The prostomium is just a narrow rib, while the peristomium is completely absent. The nuchal organs are two ciliate ribs on the sides of the prostomium. The first segments are fused together and form a gill membrane or hood from which dorsal gills arise in segments . Dorsal and ventral cirrus are absent. The animals have characteristic papillae that are particularly dense and long around the bristles. They have compound crescent-shaped and capillary-shaped bristles, but no aciculae.

The longitudinal muscles are arranged in bundles. The buccal organ lies ventrally and can be turned out, and the intestine forms loops. A throat membrane is present. The closed blood vessel system is well developed and has a central heart above the esophagus . A green pigment dissolved in the plasma, probably chlorocruorin, serves as the blood pigment . The nephridia are designed as mixonephridia, with the first pair serving as kidneys and the following pairs serving to release the gametes .

distribution and habitat

The Flabelligeridae occur in seas worldwide from the intertidal zone to the deep sea , but rarely in large numbers. Some species live in self-made living tubes , while others dig through the sediment or stay under stones, such as Flabelligera affinis . There is at least one species in the genus Pherusa that burrows through the calcareous skeleton of living corals. Flabelliderma commensalis lives as a commensal in the area of ​​the anus of sea ​​urchins , where it collects the excrement of the echinoderm with its slimy palps and transports it to the mouth via the eyelash groove.

Development cycle

The Flabelligeridae are separate sexes, but little is known about the reproductive biology of most species. Flabelligera mundata incubates its eggs in a thick layer of mucus on its back, and the embryos develop directly into creeping worms. Flabelliderma commensalis , on the other hand, releases its gametes into the open sea water, where fertilization occurs and the eggs develop into free-swimming larvae until the animals settle on sea ​​urchins and metamorphose to live as coprophages .

nutrition

Most Flabelligeridae are detritus eaters , which collect food particles or sediment grains covered with detritus with the help of their palps from the ground or from the bristles on the first two bristle-bearing segments, where the particles get caught, convey them to the mouth by striking the eyelashes and swallowing them. Flabelliderma commensalis , which eats sea urchin droppings , is an exception .

Subfamilies and genera

The more than 120 species of the Flabelligeridae family belong to the following genera :

literature

  • Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Class Polychaeta. Pp. 289-294, Family Flabelligeridae.

Web links

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

Individual evidence

  1. ↑ Flabelligeridae de Saint-Joseph, 1894. WoRMS , 2018. Accessed December 7, 2018.