Myzostomidae

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Myzostomidae
Three well camouflaged specimens of Myzostoma fuscomaculatum on their host, the hairy star Tropiometra carinata.

Three well camouflaged specimens of Myzostoma fuscomaculatum on their host, the hairy star Tropiometra carinata .

Systematics
Over trunk : Lophotrochozoa (Lophotrochozoa)
Trunk : Annelids (Annelida)
Class : Polychaete (Polychaeta)
Subclass : Aciculata
Order : Myzostomida
Family : Myzostomidae
Scientific name
Myzostomidae
Benham , 1896

The Myzostomidae are a family of marine worms known as commensals or parasites on echinoderms live (Echinodermata), most of feather stars or sea lilies , some species of starfish and brittle stars . They prefer echinoderms that live deeper than 200 m and encourage them to form small, gall-like skeletal elements that serve to protect the Myzostomidae.

features

The animals have a disc-shaped, flattened body with strong dorsal and ventral muscles and are surrounded by hook-like bristles to cling to their hosts. By parapodia and the segmental disposed side nerves of the modified into an integral mass ventral nerve cord , a is segmentation to recognize. A ganglion is located at the upper throat. The intestine has blind sacs.

Multiplication

The animals are simultaneous twitterers . The mating takes place via the mutual attachment of complex spermatophores from 5 different cell types. The spermatophore penetrates the body like a root and transports the sperm to the egg cells. There is a spiral groove . The larva is a spherical trochophora larva.

Systematics

The taxonomic classification has long been uncertain. Traditionally, the Myzostomidae were counted among the polychaeta , since many organs are arranged segmentally like the annelids. Molecular studies have confirmed this notion.

Genera

There are about 140 species in 6 genera.

literature

  • Westheide, W .; Rieger, R .: Special Zoology. Part 1: Protozoa and invertebrates. Pages 421-422, 2nd edition. Spektrum Akademischer Verlag, Heidelberg 2007 ISBN 3-8274-1575-6

Individual evidence

  1. ↑ Torsten H. Struck, Christiane Paul, Natascha Hill, Stefanie Hartmann, Christoph Hösel: Phylogenomic analyzes unravel annelid evolution . In: Nature . tape 471 , no. 7336 , March 2011, ISSN  0028-0836 , p. 95-98 , doi : 10.1038 / nature09864 .

Web links

Commons : Myzostomida  - Collection of pictures, videos and audio files
  • Fauchald, K. (2009). Myzostomidae. In: Fauchald, K. (Ed) (2009). World Polychaeta database. Accessed through: World Register of Marine Species ( accessed July 8, 2010 )