Opheliidae

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Opheliidae
Euzonus flabelligerus

Euzonus flabelligerus

Systematics
Empire : Animals (Animalia)
Trunk : Annelids (Annelida)
Class : Polychaete (Polychaeta)
Subclass : Aciculata
Order : Scolecida
Family : Opheliidae
Scientific name
Opheliidae
Malmgren , 1867

Opheliidae is the name of a family of very small to small polychaeta that can be found burrowing in the sandy subsoil in oceans around the world.

features

The fully grown polybristles of the family Opheliidae, a few millimeters to about 6 cm in size, have a mostly spindle-shaped body with inconspicuous 30 to 60 segments and only weakly developed parapodia and a compact head without appendages. The body shape of the Opheliidae varies: While the bristle worms of the genera Dindymenides and Travisia have rather short, thick and maggot -like bodies, they are very slender, smooth and torpedo-shaped in the genera Armandia and Polyophthalmus or Ophelina with the up to 6 cm large Ophelina acuminata , in the genera Ophelia , Euzonus and Lobochesis, on the other hand, inflated in front and cylindrical or narrow behind.

The quadrangular prostomium (head lobe) has neither antennae nor palps, but it can end in an elongated palpod at the front. The peristomium has receded and is either fused with the prostomium or forms a conspicuous ring. The evertable nuchal organs are paired. The longitudinal muscles of the skin muscle tube are arranged in bundles. The first segment is similar to the following, in which all parapodies are similar to one another. Both branches of the parapodia are small, and mostly the notopodium is somewhat smaller than the neuropodium . The representatives of the genus Travisia with their large, well-developed parapodic branches are an exception . The gills , designed as simple threads, sit close to the Notopodium. Back and abdominal cirrus organs are missing, as is papillae of the epidermis. The pygidium can be hood-shaped without internal and lateral cirrus or hoodless with many cirrus. The axial, simple buccal organ has a sac-like, evertable proboscis . The animals have a throat membrane.

The intestine is designed as a straight tube. In all known species, the closed blood vessel system has a central heart . To bind the oxygen , hemoglobins , which are freely dissolved in the blood and not bound to blood cells, serve as blood pigments .

Most species in the family have numerous paired nephridia , of which there are up to 27 pairs in the genera Travisia and Ophelina . In clear contrast to this, the representatives of the genus Ophelia show only three segments of nephridia, the six exits of which can sit on or next to the crests of the parapodia.

The segments often also have an eye spot on both sides .

The Opheliidae are separate sexes with the same size and roughly the same number of males and females. As far as is known, there is external fertilization and development via free-swimming larvae, which, depending on the type, live on yolk reserves or on phytoplankton .

Way of life

The animals burrow upside down in the sandy or muddy seabed.

As far as is known, all Opheliidae are detritus eaters who take up their food particles from the substrate or swallow sand particles on which there is organic material.

The Opheliidae are separate sexes. The fertilization takes place externally in the open sea water. Larvae hatch from the eggs and initially live freely swimming as zooplankton and then metamorphose into crawling worms .

Genera

The family Opheliidae is divided into 9 genera :

literature

  • Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Class Polychaeta. Pp. 99-103, Family Opheliidae.

Web links

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

Individual evidence

  1. ↑ Opheliidae Malmgren, 1867. WoRMS , 2018. Retrieved May 10, 2018.