Green ringworm
| Green ringworm | ||||||||||||
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Green ringworm ( Alitta virens ) |
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| Scientific name | ||||||||||||
| Alitta virens | ||||||||||||
| ( Sars , 1835) |
The Green ragworm ( Alitta virens , frequent synonyms : Nereis virens , Neanthes virens ) is a cosmopolitan marine annelid of the genus Alitta within the polychaete - Family of Nereididae .
features
The green ringworm has a long, narrow body with smooth skin. It becomes up to 90 cm long and then has about 200 segments . On the prostomium sit a pair of antennae without antenna support, a pair of two-part palps that are slightly longer than the antennae, and 2 pairs of eyes arranged in a trapezoid. The dorsal Tentakular - Cirrus clouds are about as long as the ventral twice; the second dorsal cirrus extends to the eighth segment. The pharynx has a pair of toothed jaws. The mouth and maxillary rings have conical paragnaths. The articulated bristles are long and thin.
The parapodia of the first two bristle-bearing segments are single-branched with three lobes. All other parapodia have two branches with 4 lobes that vary little in shape and size across the body. The dorsal lobe of the notopodium , which is leaf-shaped, especially in large animals, is the longest. The lobe of the acicula of the notopodium is bilobed and the lobe above the aciula is always shorter than the one below. The lobe of the acicula of the neuropodium is also bilobed, and the lobe above the aciula is always shorter than the one below; In addition, behind the bristles, a rag protrudes over the acicula. On the posterior segments, the lobes differ only slightly in size. The dorsal cirrus starts at the dorsal edge of the dorsal lobe of the notopodium.
The animal is dark green and shimmers bluish. The lobes of the parapodia are lined with yellow.
distribution and habitat
Alitta virens is widespread as a cosmopolitan, including in the northern Atlantic Ocean including the North Sea , the Skagerrak , Kattegat , the Arctic and the northern Pacific Ocean .
The green ring worm lives on different types of sediment, such as soft mud, muddy sand or coarse-grained substrate. In contrast to Hediste diversicolor , it does not penetrate into river estuaries, as it apparently does not tolerate water with little salt.
It digs in the sediment and lines its passages with slime, but it can also swim like a snake.
Life cycle
The green ringworm is separate sexes with females and males of roughly equal size and external fertilization. In contrast to the amber ringworm , the sexually mature female of the green ringworm does not change its external shape at all and the sexually mature male as epitoke only slightly, with the dorsal cirrus lengthening at the parapodia of the anterior segments and small sails on the dorsal cirrus at the posterior segments arise. Females and males come together in large numbers and die after mating. After external fertilization, the eggs develop into larvae that swim freely as zooplankton and later metamorphose into crawling worms .
nutrition
Alitta virens is an omnivore that swallows substrate particles in order to digest adhering detritus and microorganisms, but it also preyes on more agile small animals, especially other polychaetes such as the opal worm , and ingests carrion.
literature
- JD Fish, S. Fish: A Student's Guide to the Seashore. Cambridge University Press, Cambridge 2011. p. 160.
- PJ Hayward, JS Ryland: Handbook of the Marine Fauna of North-West Europe. Oxford University Press, Oxford 1995. p. 210.
- Edwin P. Creaser, David A. Clifford: Life History Studies on the Sandworm, Nereis Virens Sars, in the Sheepscot Estuary, Maine. State of Maine Department of Marine Resources Fisheries Research Station, 1981.
Web links
- MJ de Kluijver et al .: Nereis virens Sars, 1835. Macrobenthos of the North Sea - Polychaeta, Marine Species Identification Portal