Krause drill shell
| Krause drill shell | ||||||||||||
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Curled burr mussel ( Zirfaea crispata ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Zirfaea crispata | ||||||||||||
| ( Linnaeus , 1758) |
The Krause piddock or Rough piddock (lat. Zirfaea crispata ) is a drilling into soft sediments or softer rocks and wood shellfish species from the order of Myida .
features
The flared, inflated housing is up to about 9 cm long. With a height of 4.7 cm, this results in a length-to-width ratio of 1.9. It is roughly rectangular in outline with rounded corners. The front edge of the housing is pointed at an acute angle, the rear edge of the housing is rounded and slightly trimmed. The two flaps gape at the back and especially at the front end. The casing is unequal, the vertebrae are in front of the center. The flaps are turned up and out in front of the vertebra and protrude beyond the vertebra. An additional triangular piece of shell has developed between the two flaps.
From the vertebra a depression (sulcus) runs obliquely backwards from the vertebra, approximately to the middle of the ventral margin. The rear part of the case bears only concentric growth strips of varying strength, the front part is heavily ornamented with concentric growth strips and radial ribs. The intersection of ribs and strips of growth are drawn out into small thorns, giving the gaping foot opening a serrated edge. The lock is without teeth. A long process is developed on both valves, to which the foot muscle attaches. The front "sphincter" sits on the outside of the envelope of the valves. By attaching the "sphincter" to the outside of the envelope of the valve, the muscle opens the front part of the housing when it contracts. The posterior sphincter actually pulls the two valves together when it contracts. The siphons reach about twice the length of the housing and can no longer be completely withdrawn into the housing. The coat is broad and deeply indented; the bay extends up to about half of the total length. The skin is firm and whitish. The inner edge smooth. The periostracum is light brown.
Geographical distribution, habitat and way of life
The Krause drilling mussel occurs on both sides of the North Atlantic and in the North Pacific (Sakhalin). In Europe the distribution area extends from the Bay of Biscay to Norway and Iceland. In eastern North America from Delaware to Labrador. It is also native to the North Sea and the western Baltic Sea .
The species occurs from the tidal range to about 16 m depth. The rear end faces the opening of the borehole; the siphons extend to the opening and swirl in water rich in oxygen and nutrients. It drills mechanically in peat, solidified clay, soft limestone or, more rarely, in wood. The strongly ornamented front part of the housing is pressed against the rear wall of the borehole, the foot moves the housing slightly around its longitudinal axis. In doing so, some material is scraped off the inner wall of the borehole. The boreholes are driven about 15 cm into the substrate, more rarely up to 30 cm. The Krause burr mussel lives individually, not like the American burr mussel ( Petricola pholadiformis ) in colonies.
Taxonomy
The taxon was established by Carl von Linné in 1758. It is the type species of the genus Zirfaea Gray, 1842. Synonyms are: Pholas bifrons da Costa, 1778, Zirfaea crispata var. Truncata Kaas, 1939 and Zirfaea crispata var. Typica Locard.
supporting documents
literature
- Fritz Nordsieck: The European sea shells (Bivalvia). From the Arctic Ocean to Cape Verde, the Mediterranean Sea and the Black Sea. 256 p., Gustav Fischer Verlag, Stuttgart 1969 (p. 152)
- Guido Poppe and Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 p., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc. Reprint), ISBN 3925919104 , p. 132/33.
- Rainer Willmann: Mussels and snails of the North and Baltic Seas. 310 pp., Neumann-Neudamm, Melsungen 1989, ISBN 3-7888-0555-2 , pp. 188/89
On-line
Individual evidence
- ↑ a b MolluscaBase: Zirfaea crispata (Linnaeus, 1758)
- ^ Carl von Linné: Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Pp. 1-824, Holmia / Stockholm, Salvius, 1758. Online at www.biodiversitylibrary.org (p. 670).