Bonelliidae

from Wikipedia, the free encyclopedia
Bonelliidae
Bonellia viridis (adult female)

Bonellia viridis (adult female)

Systematics
Empire : Animals (Animalia)
Trunk : Annelids (Annelida)
Class : Hedgehog worms (Echiura)
Order : Echiuroidea
Subordination : Bonelliida
Family : Bonelliidae
Scientific name
Bonelliidae
Lacaze-Duthiers , 1858

Bonelliidae is the name of a family of hedgehog worms (Echiura), whose representatives, which are widespread in seas around the world, are characterized by a pronounced sexual dimorphism : The dwarf males live inside or on the proboscis of the much larger females, on which they are completely dependent for nutrition and protection are. The species Bonellia viridis , which also lives in European waters, has been studied best .

features

The females of the Bonelliidae have a 0.7 to 15 cm long, egg, cigar or sausage-shaped trunk, which is usually light to dark green in color. The proboscis , whose distal end is often forked, can be extended to many times the length of the trunk and is used to graze microscopic food particles from the sediment. On the trunk, the mouth sits near the base of the proboscis. The females have one or two nephridia that also serve as fallopian tubes , with a nephrostome sitting in front at the base or at the end. Usually there are two ventral bristles (Chaetae), which are missing in some deep-sea species, while anal bristles are always missing. The two anal vessels are usually heavily branched. As with most hedgehog worms, the blood vessel system is closed, with the dorsal and neurointestinal vessels connected by capillaries or lacunae in the intestinal wall.

The mostly 1 to 6 mm long, flattened and unpigmented dwarf males in Metabonellia live in most species in the female's nephridium, which also serves as a fallopian tube, but in some species on the outside of the proboscis or in a special tube inside the female, usually in larger numbers. With the exception of the strongly developed testicles , the internal organs such as the intestinal canal, blood vessel system and nervous system are greatly reduced in the male , but at least the coelom and nephridia are fully developed in the male of Bonellia viridis . The body surface of the males is covered with ciliate cells. The males are fed by the body fluids of the female.

Distribution and habitat and way of life

Hedgehog worms of the Bonelliidae family are found worldwide in both cold and warm seas, from shallow waters to the deep sea. They hardly move their trunk, which is anchored in a cave in the sand, mud or rock, but instead stretch their proboscis to several times the length of the trunk to graze detritus and microorganisms from the substrate. So far no Bonelliidae have been observed digging a cave; existing caves, often dug by other animals, are populated.

Some sample styles

In the eastern Atlantic Ocean , including the North Sea and the Mediterranean is Bonellia viridis widespread in addition to the sexual dimorphism and phenotypic sex determination has been thoroughly investigated. In Australian waters, Metabonellia haswelli and Pseudobonellia biuterina are common, both of which, like Bonellia viridis, are characterized by a green skin color and a forked proboscis.

Initial description

The Bonelliidae family was established in 1858 by the French zoologist Lacaze-Duthiers . The type genus is Bonellia Rolando 1821.

Internal system

The Bonelliidae family is divided into 41 genera :

literature

  • Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Phylum Echiura. Pp. 21-23, Family Bonelliidae.

Web links

Commons : Bonelliidae  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Bonelliidae Lacaze-Duthiers, 1858. WoRMS , 2018. Retrieved on 10 May 2018th