Brackish triangle clam
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Brackish triangle clam ( Mytilopsis leucophaeata ) |
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| Mytilopsis leucophaeata | ||||||||||||
| ( Conrad , 1831) |
The brackish Wedge shell ( Mytilopsis leucophaeata ) is a shell - type from the family of zebra mussels (Dreissenidae). For Europe, it is an invasive species that was introduced to the European coasts from North America with ballast water in ships.
features
The flared case is slightly uneven, the right flap is slightly larger than the left flap. It is rounded wedge-shaped (mytiliform) or narrow wedge-shaped in outline. It is therefore very clearly unequal. The size is generally 10 to 15 millimeters, up to a maximum of 2.7 centimeters. The vertebrae sit near the front end. The ligament is external but sunk. It extends over half of the dorsal margin. The lock has a triangular tooth (or saprophyte) that attaches to the inner dorsal ridge (or myophore plate). There are two sphincters. The posterior sphincter muscle and the posterior foot retraction muscle are fused into one large, crescent-shaped muscle or muscle impression in the posterior dorsal region. The surface line is slightly concave below the sphincter / foot muscle.
The aragonitic shell is thin, but still quite firm. It consists of cross slats and complex cross slats. The ornamentation consists only of growth strips that are crowded at irregular intervals and represent growth interruptions. The inner edge of the case is smooth. The brown periostracum is thick with dense and upright lamina. The inside of the shell is whitish with a purple tint.
Similar species
The brackish triangular mussel ( Mytilopsis leucophaeta ) differs from the migrant mussel ( Dreissena polymorpha ), which is very variable in terms of color and morphology, in that it has a pointed vertebra, the angular transition between the ventral and the rear edge and the pointed ventrolateral shoulder, as well as the presence of a triangular tooth (or Apophysis) in the lock area.
Geographical distribution, habitat and way of life
The original range of the brackish triangular mussel was the northern coastal waters of the Gulf of Mexico (south coast of the USA to Tampico, Mexico). Through displacement, it has expanded its range to the north along the east coast of the USA to the mouth of the Hudson River , and in the south to Brazil . It also came to Europe in the ballast water of ships and is now found in the Baltic Sea from Denmark , southern Sweden and southern Finland along the European coasts (including the British Isles ) to the Mediterranean and the Black Sea . It has also been found in the Caspian Sea .
It lives in the tidal area of brackish lagoons , estuaries and harbors , attached to hard substrate (e.g. stones, oysters, ropes and boats) with byssus .
development
The animals are separate sexes, the sex products are released (in Europe) from the end of May / beginning of June to September synchronously into the open water, where fertilization takes place. The eggs have a diameter of about or greater than 32 µm. After just 24 hours, free-swimming trochophora larvae with a cilia ring and a prototroch with a diameter of 63 µm appear. After two days, the larva changes into a freely swimming Veliger larva, which forms a first D-shaped bowl. This has a dorsal length of 50 or a total length of 90 µm. In a later Veliger stage, a first umbo is formed, the small housing is then 109 to 150 µm in size. Then the Pediveliger develops, the housing is now 145 to 220 µm in length, and the larva changes to metamorphosis and life on the ground after 6 to 10 days . The animals filter phytoplankton and organic detritus from the water. They live to be up to five years old.
Adult brackish water triangular clams can survive at salinities of 0.1 to 31 PSU (Practical Salinity Units). Larvae are a little more sensitive and can only develop at salinities of 3 to 22 PSU. Open sea areas with normal salinity are therefore insurmountable barriers to the natural distribution of the species. It can therefore only bridge open sea areas with normal salinity using ballast water from ships.
Taxonomy
The species was established by Timothy Abbott Conrad in 1831 under the original binomial Mytilus leucophaeatus . It is the type species of the genus Mytilopsis Conrad, 1857.
supporting documents
literature
- Diane A. Pathy, Gerald L. Mackie: Comparative shell morphology of Dreissena polymorpha, Mytilopsis leucophaeata, and the "quagga" mussel (Bivalvia: Dreissenidae) in North America. In: Canadian Journal of Zoology. 71, 1993, pp. 1012-1023. (PDF)
- Dan C. Marelli, Susan Gray: Conchological redescriptions of Mytilopsis sallei and Mytilopsis leucophaeta of the brackish western Atlantic. In: The Veliger. 25 (3), 1983, pp. 185-193. (online at www.biodiversitylibrary.org)
- Scott E. Siddall: Early Development of Mytilopsis leucophaeata (Bivalvia: Dreissenacea). In: The Veliger. 22 (4), 1980, pp. 378-379.
- Annick Verween, Magda Vincx, Steven Degraer: Mytilopsis leucophaeata: The brackish water equivalent of Dreissena polymorpha? A review. In: G. Van der Velde, S. Rajagopal, A. Bij de Vaate (eds.): The Zebra Mussel in Europe. Backhuys Publishers, Leiden 2010, ISBN 978-90-5782-189-9 , pp. 29-43. (PDF)
On-line
Individual evidence
- ^ Ari O. Laine, Jukka Mattila, Annukka Lehikoinen: First record of the brackish water dreissenid bivalve Mytilopsis leucophaeata in the northern Baltic Sea. In: Aquatic Invasions. 1, 2006, pp. 38-41. (PDF)
- ↑ Thomas W. Therriault, Margaret F. Docker, Marina I. Orlova, Daniel D. Heath, Hugh J. MacIsaac: Molecular resolution of the family Dreissenidae (Mollusca: Bivalvia) with emphasis on Ponto-Caspian species, including first report of Mytilopsis leucophaeata in the Black Sea basin. In: Molecular Phylogenetics and Evolution. 30, 2004, pp. 479-489.
- ↑ Katharina CM Heiler, Nahid Nahavandi, Christian Albrecht: A New Invasion Into an Ancient Lake - The Invasion History of the Dreissenid Mussel Mytilopsis leucophaeata (Conrad, 1831) and Its First Record in the Caspian Sea. In: Malacologia. 53 (1), 2010, pp. 185-192. doi : 10.4002 / 040.053.0112
- ^ Timothy Abbott Conrad: Description of Fifteen New Species of Recent, and three of Fossil Shells, chiefly from the coast of the United States. In: Journal of the Academy of Natural Sciences of Philadelphia. 6, Philadelphia 1831, pp. 256-268. online at www.biodiversitylibrary.org (p. 263)
- ↑ MolluscaBase: Mytilopsis leucophaeata (Conrad, 1831)