Colored ringworm
| Colored ringworm | ||||||||||||
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Colored ringworm ( Neanthes fucata ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Nereis fucata | ||||||||||||
| ( Savigny , 1820) |
The Colored ragworm ( Neanthes fucata , frequent synonym Nereis fucata ) is up to 20 cm large marine annelid from the genus Nereis within the polychaete - family of the Nereidae , the at commons Einsiedlerkrebs as commensal lives.
features
The colored ringworm has a long body that narrows towards the back with a smooth surface and a yellowish back with red and white vertical stripes. It becomes up to 20 cm long and then has about 120 segments . His prostomium has a pair of antennae without antenna support and a pair of two-part palps that are slightly shorter than the antennae, as well as 2 pairs of eyes arranged in a trapezoid.
The bristle-free first segment is about twice as long as the first bristle-bearing segment and sometimes appears inflated; it bears four pairs of tentacles - cirrus , which differ slightly in length, with the second dorsal tentacle-cirrus reaching to the fourth bristle-bearing segment.
The pharynx has a pair of toothed jaws. Conical paragnaths protrude from the oral and maxillary rings. The articulated bristles are long and thin.
The parapodia of the first two segments are single-branched with 3 lobes, while the remaining segments have two branches with 4 lobes, the dorsal lobe of the notopodium being the largest and the middle and rear segments having a leaf-like shape, especially in larger animals. The other lobes are quite uniform in shape over the entire length of the body. The acicula lobe of the notopodium and the slightly smaller ventral lobe of the neuropodium are designed similarly, while the acicula lobe of the neuropodium tapers into a very pointed end and is the shortest.
In the case of the epitoken , the body is divided into two sections, the front section comprising 24 bristle-bearing segments in males and 27 to 29 in females. There are no changes in the dorsal or ventral cirrus of the anterior segments, as it is known. In the posterior section of the body, on the other hand, the parapodia metamorphose in both sexes with the formation of well-developed accessory valves at the base of the dorsal cirrus, below the lobe of the acicula of the notopodium, on the posterior surface of the lobe of the acicula of the neuropodium, and at the base of the ventral one Cirrus. In males, fine notches can develop on the lower edge of the dorsal cirrus, but no pygidial rosette is known. In both sexes, the common bristles are replaced by paddle-shaped bristles on modified parapodia, even if individual bristles of the atoke can remain in females.
Distribution, habitat and way of life
Nereis fucata is distributed in the northern Atlantic Ocean including the North Sea and Kattegat, as well as in the Mediterranean and Black Sea .
Nereis fucata lives as a commensal in the snail shells inhabited by the common hermit crab ( Pagurus bernhardus ). While it is only found in a few hermit crabs in the German Bight , it can also occur in half of all hermit crabs on the French coast. Occasionally the polychaet is found without the hermit crab, but this is likely to be a transitional situation. It usually lives in the smaller coils of the snail shell and leaves these when the crab eats to take part in its meal without getting too close to the crab claws.
Life cycle
The colored ringworm is sexually separated with females and males of roughly the same size, which come together in large numbers free-swimming as sexually mature female and male epitokes with leaf-like enlarged parapodia and die after the gametes are released into the sea water. The fertilization takes place in the open sea water. After fertilization, larvae develop from the eggs and live freely swimming as zooplankton until they sink and metamorphose into creeping worms .
literature
- JD Fish, S. Fish: A Student's Guide to the Seashore. Cambridge University Press, Cambridge 2011. Neanthes fucata (Savigny) (Nereis fucata) , pp. 160f.
- PJ Hayward, JS Ryland: Handbook of the Marine Fauna of North-West Europe. Oxford University Press, Oxford 1995. Neanthes fucata (Savigny) , p. 210.
- Volker Storch: Sea bristle worms (Polychaeta). Ziemsen, Wittenberg 1971, p. 70.
Web links
- MJ de Kluijver et al .: Nereis fucata (Savigny, 1820). Macrobenthos of the North Sea - Polychaeta, Marine Species Identification Portal