Capitellidae

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Capitellidae
Capitella capitata

Capitella capitata

Systematics
Empire : Animals (Animalia)
Trunk : Annelids (Annelida)
Class : Polychaete (Polychaeta)
Subclass : Scolecida
Order : Capitellida
Family : Capitellidae
Scientific name
Capitellidae
Pit , 1862

Capitellidae is the name of a species-rich family of Vielborstern (Polychaeta) in seas worldwide either tube-making can be found or without tube in the sediment.

features

The often reddish colored multi-bristle of the family Capitellidae have a long, cylindrical body with up to 100 segments and only weakly developed parapodia , in which the bristles seem to sit directly on the body wall, which gives the worms an outward resemblance to earthworms. The body is clearly divided into the thorax and abdomen.

The clearly furrowed prostomium is shaped like a short, truncated cone, while the peristomium forms a ring around the mouth. The animals have neither antennae nor palps, but they have a pair of pit-shaped nuchal organs . The longitudinal muscles of the skin muscle tube are arranged in clear bundles.

While the first segment, which is longer than the second segment, has neither parapods nor bristles , these are present in all other segments. Both branches of the parapodia, which are often deeply drawn back into the body wall, have short, trimmed lobes on the first bristle-bearing segments, while tori on the rear segments . Dorsal and ventral cirrus organs are absent, as is the epidermal papillae. Cirrus on the Pygidium can be present in different numbers or even absent.

The Capitellidae have neither gills, nor hearts nor blood vessels. The celomial fluid contains cells with hemoglobin , and some authors speak of an open blood vessel system. In some species, extensions of the posterior wall of the body into the hollows of the coelom can possibly take over the function of gills. The intestinal canal is a straight tube. The animals have nephridia ; in addition, coelomoducts form as outputs for the gametes at sexual maturity .

Females and males are the same size in the Capitellidae and in most species can only be distinguished during mating on the basis of their differently colored gametes . At least in some species of capitella there seems to be mating and internal fertilization, in which all 50 egg cells up to 10,000 egg cells are fertilized as they pass through the fallopian tube. It is controversial whether hermaphroditism and self-fertilization also occur. Some species hatch their eggs, and there are free-swimming larvae that vary in length from plankton to metamorphosis into crawling worms.

Some species of Capitellidae build mucus tubes on the surface of the sediment, while others burrow in the sand and line their passages with mucus.

The Capitellidae feed on detritus and microorganisms, which they graze on the substrate with the everted pharynx.

Some sample styles

Among the most common representatives of Capitellidae the two cosmopolitan species include head worm ( Capitella capitata ) and Kotpillenwurm ( Heteromastus filiformis ).

Genera

The family Capitellidae is divided into 46 genera :

literature

  • Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Class Polychaeta. Pp. 87-93, Family Capitellidae.

Web links

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

Individual evidence

  1. ↑ Capitellidae Grube, 1862. WoRMS , 2018. Retrieved May 10, 2018.