Echiurus

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Echiurus
Echiurus echiurus, from Brockhaus-Efron, 1905

Echiurus echiurus , from Brockhaus-Efron, 1905

Systematics
Trunk : Annelids (Annelida)
Class : Hedgehog worms (Echiura)
Order : Echiuroidea
Subordination : Echiurida
Family : Echiuridae
Genre : Echiurus
Scientific name of the  family
Echiuridae
Quatrefages , 1847
Scientific name of the  genus
Echiurus
Guérin-Méneville , 1831

Echiurus is the name of a genus of hedgehog worms (Echiura), which at the same time forms the monogeneric family of Echiuridae and includes 4 species in Arctic and Antarctic waters, partly as far as the North Sea .

features

The hedgehog worms of the Echiuridae family have two rings with protruding bristles around the anus at the end of the trunk. At the front there are two hooks on the abdomen. Behind the pharynx is a diaphragm which almost divides the coelom into two parts. The proboscis can be long and almost tubular or shorter and spatulate. The animals have 1 to 3 pairs of nephridia , in which the lips of the nephrostomata are not coiled in a spiral. The blood vessel system is closed and consists of a short back vessel in the anterior region, a longer abdominal or central vessel along the main nerve cord and a neurointestinal vessel, which are connected by a circular sinus on the intestine. The blood contains amebocytes but not red blood cells. The longitudinal muscles of the cutaneous muscle tube sit between the outer ring muscles and the inner transverse muscles.

Males and females are the same size. Fertilization is external and development is via a swimming trochophora larva.

The 10 to 15 cm long quappworm ( Echiurus echiurus ), which also occurs in front of the Elbe estuary , has been studied best as the first hedgehog worm species ever described by Peter Simon Pallas in 1766 .

species

There are currently 4 recognized types:

literature

  • Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Phylum Echiura. Pp. 18f., Family Echiuridae.
  • JD Fish, S. Fish: A Student's Guide to the Seashore. Cambridge University Press, 2011. p. 380.
  • Fritz Baltzer : Echiurida. In: Thilo Krumbach (Ed.): Handbuch der Zoologie, second volume, Vermes Amera , pp. 403–448. Walter de Gruyter, Berlin and Leipzig 1934.

Web links

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

Individual evidence

  1. ↑ WoRMS (2018). Echiurus Guérin-Méneville, 1831 and Echiuridae Quatrefages, 1847. Retrieved May 12, 2018