Marbled bean shell
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Marbled bean clam ( Musculus subpictus ) |
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| ( Cantraine , 1835) |
The marbled bean clam ( Musculus subpictus , syn .: Modiolarca subpicta , Modiolarca marmorata , Modiolarca tumida ) is a type of mussel from the family of mussels (Mytilidae). It usually lives epizoically on sea squirts.
features
The puffed up, strongly convexly curved casing of the marbled bean clam is up to 22 millimeters long. It is elongated-egg-shaped, slightly truncated at the front end and narrowing at the rear end. The dorsal margin is strongly curved, the ventral margin, however, only slightly convexly curved. The high rounded vertebra sits almost at the front end. The housing is divided into three fields, a front field with 15 to 18 radial ribs, a middle field with fine radial stripes and a rear field with 20 to 35 radial ribs. The ribs end in small nodules at the edge of the case. The radial ribs and stripes intersect with very fine growth stripes. The shell is colored green-yellow with red-brown spots arranged in a zigzag pattern. The periostracum is light green, after removing the periostracum the shell is white with a fine yellow-brown zigzag pattern. The slightly iridescent, shiny insides of the flaps are yellowish white. The sphincter muscles leave only indistinct impressions, a front long and narrow impression and a rear, larger and circular impression. The ligament is on the outside. The lock edge is short, almost straight; the lock has no teeth. The surface line is not indented. The foot is long and finger-shaped.
Similar species
In contrast to the green and black bean clams ( Musculus discors and Musculus niger ), the marbled bean clam has a pelagic larval stage. It usually lives epizoically on sea squirts.
Geographical distribution and way of life
The marbled bean clam occurs in the eastern North Atlantic from northern Norway to southwest Africa (Angola). It also penetrates into the North Sea, the western Baltic Sea and the Mediterranean Sea. It occurs from about 10 meters water depth to over 1000 meters water depth.
The marbled bean clam attaches itself to algae, under stones or under empty mussel flaps, or to the mantle of sea squirts (ascidia), usually near the siphons of the sea squirt. The mussels do not dig into the mantle of the sea squirt, but press pockets or depressions in the mantle where the mussel resides. The animals are there with the dorsal side down in the depressions and pockets of the sea squirt coat. The bags are spun with byssus threads.
development
The sexes cannot (yet) differentiate in winter. The gonads only develop from stem cells towards the end of January / beginning of February. The release of the sex products begins in July and ends in early September. The gonads regress by December, followed by a period of rest. The egg measures about 60 µm in diameter. The development proceeds through a pelagic larval stage. The larvae stay in the plankton for about four to six weeks. The Prodissoconch I measures around 95 µm. After the metamorphosis, the young mussels attach themselves to the mantle of the sea squirt and crawl, front end first, on the mantle to the siphons of the sea squirt, where they are attached with a few threads of byssus. The following types were observed Marbled beans Shell moved to its jacket: Ascidia mentula , Ascidia sordida , Ascidia conchilega , Ascidiella aspera , Ascidiella scabra , Polycarpa pomaria , Dendrodoa parallelogramma , Dendrodoa grossularia , Styela coriacea , Styela plicata , Ciona intestinalis , Microcosmus sulcatus and Phallusia mamillata . Up to 176 mussel larvae were found on a 40 millimeter large sea squirt. On the great majority of the acidia, however, only four or fewer mussels settle. Occasionally Holothuria ( Holothuria tubulosa ) are also colonized. The mussels are usually two to three, very rarely four years old. After the death of the populated host, the mussels can either move on to soil life or look for a new host.
Taxonomy
Taxonomy and nomenclature of this type is involved. Not only has the species been described several times under different names, but whether it belongs to the genus has been or is still controversial. The oldest description of the species comes from François-Joseph Cantraine , who first described the species as Modiolus subpictus . Forbes described the species three years later under the name Mytilus marmoratus ; However, the name is already taken by Mytilus marmoratus Schroeter, 1803. Another more recent synonym is Modiola tumida Hanley, 1843. The MolluscaBase lists the species under Musculus subpictus .
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. 36)
- 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. 51, as Musculus subpictus )
- Rainer Willmann: Mussels and snails of the North and Baltic Seas. 310 p., Neumann-Neudamm, Melsungen 1989, ISBN 3-7888-0555-2 (p. 103, as Musculus (Modiolarca) marmoratus )
- PM Bodger, JA Allen: The ecology and life cycle of a population of Modiolarca tumida (Hanley, 1843) (Bivalvia: Mytilidae) of the coast off North Eastern England. Journal of Molluscan Studies, 74: 97-101, 2008 (as Modiolarca tumida )
Individual evidence
- ↑ Cantraine, F .: Les diagnoses ou descriptions succintes de quelques espèces nouvelles de mollusques. Bulletins de l'Académie Royale des Sciences et Belles-Lettres de Bruxelles, 1.série, 2 (11): 380-401 1835. Online at www.biodiversitylibrary.org (p. 397)
- ↑ MolluscaBase: Musculus subpictus (Cantraine, 1835)
