Straight vaginal concha
| Straight vaginal concha | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
![Straight vaginal clam (Ensis magnus) (Original illustration by Schumacher 1817: Plate 14, Fig. 1 [1])](https://de.wikipedia.org/wiki/Datei:Schumacher1814_pl14_fig1_Ensis_magnus.png)
Straight vaginal clam ( Ensis magnus ) (original illustration by Schumacher 1817: plate 14, fig. 1) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Ensis magnus | ||||||||||||
| ( Schumacher , 1817) |
The Straight clams ( Ensis magnus , Syn. : Ensis arcuatus ) is a mussel from the family of Pharidae , also in the North Sea is common.
features
The equally-folded, slightly curved to straight housing is up to 20 cm long and up to 3 cm wide. It is very slim, so it has only a small thickness (measured in cross section). It is unequal because the vertebrae sit on the front edge of the case. The dorsal and ventral margins run almost parallel, the ventral margin is slightly (more) bulged. The anterior and posterior margins are truncated slightly obliquely and only slightly convexly curved. The rear end gapes, the opening is egg-shaped in cross section.
The ligament is a long, narrow, blackish-brown colored band behind the vertebrae. In the left valve there are two protruding, peg-shaped cardinal teeth and two elongated posterior lateral teeth, one above the other. The right valve has only one laminar cardinal tooth, and only one elongated lateral tooth. There are two sphincter muscles, whose attachments to the shell are clearly visible. The anterior sphincter is dorsal, elongated, and extends beyond the ligament. The posterior sphincter is small but clearly separated from the U-shaped mantle bay. The jacket bay at the rear end is rather small.
The brittle skin is white to cream-colored with red-brown or orange rays and spots. The ornamentation consists of fine growth strips and growth interruptions. The inner edge of the case is smooth. The periostracum is yellowish-greenish to dark green and becomes darker and brownish towards the edges. The inside is white with a pink or light purple tint.
Similar species
The American sheath clam ( Ensis americanus ) has an inverted S-shaped mantle sinus and a slightly wider housing.
Geographical distribution, habitat and way of life
The distribution area of the straight vaginal clam extends from Norway to the Iberian Peninsula . It occurs from about 15 to 40 m water depth.
The straight vaginal clam lives buried in fine or silty sand, more rarely in coarse sand or gravel. It sticks vertically in a tube with the rear end and the siphons up. During low tide, it can withdraw its foot up to 50 cm into its tube. In north-western Spain, the straight vaginal clam becomes sexually mature within a year at a size of around 80 mm. However, the onset of sexual maturity varies greatly from region to region. In Scotland it has been observed that sexual maturity only occurs there from a size of 81 to 90 mm, some specimens only reach it with a case length of 120 to 130 mm. At this point the animals are already four or five years old. The species has crept separately, and individual hermaphroditic specimens are very rare.
Taxonomy
Ensis magnus is considered by some authors to be a synonym of Ensis ensis Linnaeus, 1758. MolluscaBase considers the taxon to be an independent species, with the younger synonym Ensis arcuatus (Jeffreys, 1865).
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. 146 Ensis magnus and Ensis arcuatus )
- Guido Poppe & Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 p., Verlag Christa Hemmen, Wiesbaden 1993 (2000, un. Reprint). ISBN 3925919104 (p. 107)
On-line
- Marine Bivalve Shells of the British Isles: Ensis magnus Schumacher, 1817 (site of the National Museum Wales, Department of Natural Sciences, Cardiff)
- Marine Species Identification Portal: Ensis arcuatus (Jeffreys, 1865)
Individual evidence
- ^ Christian Friedrich Schumacher: Essai d'un nouveau système des habitations des vers testacés Avec XXII Planches. 287 p., Copenhagen, Schultz, 1817 Online at www.biodiversitylibrary.org (p. 143)
- ↑ MolluscaBase: Ensis magnus Schumacher, 1817
Web links
- Ensis arcuatus (Jeffreys, 1865) Conchological Society of Great Britain and Ireland (accessed May 7, 2016).