Tethydidae
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| Rafinesque-Schmaltz , 1815 |
The Tethydidae are a family of mostly medium-sized to large tree snails in the subordination of the nudibranchs . They are exclusively marine , caseless snail species , some of which swim and mainly eat small crabs .
features
The Tethydidae have an extraordinarily large head, which is provided with a wide funnel-shaped "veil" (velum). The animals have no antennae and only very short, conical rhinophores . The back is covered on both sides with cerata of different shapes depending on the species , at the base of which sit gills. Processes lead from the compact midgut gland into the cerata, which can be rejected to distract enemies ( autotomy ).
Pine occurs only in some species of the genus Melibe and is absent in the other species, while a radula is absent in all species of the family. The anus opens on the side of the back above the emergency border.
Like other tree snails, the Tethydidae are hermaphrodites that, like many other swimming snails, have particularly long egg and seminal ducts. A receptaculum seminis for receiving the sperm from the sexual partner is available and, depending on the type, located at another point in the vagina or fallopian tube. The snails mate with each other. Numerous Veliger larvae hatch from the eggs, feed on plankton and, after a long pelagic phase, metamorphose into small shell-less snails .
The Tethydidae live on the sea floor or on aquatic plants. Even as adults, they move partly or mainly by swimming, but mostly stay close to the ground. With their mouth sail (veil) they mainly prey on small crabs , but also jellyfish , which are swallowed as a whole due to the lack of radula and jaws.
Spread and some species
The range of the Tethydidae includes all warm seas worldwide. Two of the largest species are up more than 30 cm of length, mainly in the Mediterranean living veil screw ( Tethys fimbria ) and the Indo-Pacific live, via the Red Sea immigrants into the Mediterranean Melibe viridis . On the Pacific coast of North America , among others, which is lion head screw ( Melibe leonina ) at home.
Systematics
According to Bouchet and Rocroi (2005) the family Tethydidae is one of nine families in the superfamily Tritonioidea , which in turn forms the suborder Dendronotida. The Tethydidae family includes two genera:
- Melibe rank, 1829 with 16 species
- Tethys Linnaeus, 1767 with 3 species, including the type species Tethys fimbria Linnaeus, 1767
The generic names Chioraera Gould, 1852, Jacunia de Filippi, 1867, Melibaea Angas, 1864 and Propemelibe Allan, 1932 are synonyms of Melibe Rang, 1829.
In 1981 the name of the nudibranch family with the type genus Tethys was set to Tethydidae (with d ) in order to differentiate them from the sponges of the family Tethyidae (type genus Tethya ), while the genus name of the sea squirts Tethyus and thus the name Tethyidae derived from there is now invalid.
literature
- Luise Schmekel, Adolf Portmann: Opisthobranchia of the Mediterranean: Nudibranchia and Saccoglossa . Springer-Verlag, Berlin Heidelberg New York 1982. Tethyidae [sic] Alder and Hancock, 1855 : p. 156.
- Adam Sedgwick, Joseph Jackson Lister, Sir Arthur Everett Shipley: A Student's Text-book of Zoology: Protozoa to Chaetognatha . S. Sonnenschein and Company, 1898. Tethyidae [sic]: p. 412.
- Philippe Bouchet & Jean-Pierre Rocroi: Part 2. Working classification of the Gastropoda . Malacologia, 47: 239-283, Ann Arbor 2005 ISSN 0076-2997
Web links
Individual evidence
- ^ A b World Register of Marine Species , Tethydidae Lamarck, 1809
- ^ RV Melville (Secretary ICZN), International Commission on Zoological Nomenclature: Opinion 1182, 1981. Tethyidae in Mollusca, Porifera and Tunicata: Removal of homonymy . Bulletin of Zoological Nomenclature 38 (3), 1981, pp. 174-177.