Thecosomata

This article deals with the snail suborder Thecosomata, not to be confused with the snail family Strombidae , which is also referred to as "wing snails ".

Thecosomata
Thecosomata
Systematics
Trunk : Molluscs (mollusca) Class : Snails (gastropoda) Subclass : Orthogastropoda Superordinate : Heterobranchia Order : Hind gill snails (Opisthobranchia) Subordination : Thecosomata
Scientific name
Thecosomata
HDM de Blainville , 1824

The Thecosomata (Greek for “shell body”), formerly Pteropoda (“winged fish”), also known as “sea butterflies” or “winged snails”, are a subordination of the hind- gill snails . The planktonic sea ​​snails are all very small; the size of their housing is usually less than 1 cm.

features

The thecosomata show a number of adaptations to the planktonic way of life. So your foot has the shape of two wing-shaped lobes (parapodia), with which you can float backwards in the open water or move actively by rowing. Their calcareous shells, which are very different in shape, are, if present, bilaterally symmetrical , like the whole animal mostly colorless and usually less than 1 cm long. The shell and gills have regressed in some families.

The snails live on plankton, which in some species is caught with a net that is up to 5 cm wide and larger than the snail. In the event of a fault, the net is dropped. The animals migrate vertically during the day, following their plankton food: at night they are close to the surface, during the day at greater depths.

Systematics

The taxonomy of snails is subject to revision and change. Therefore there are different classifications. The one that goes back to J.Thiele (1929–1935) is usually considered classic . It was recognized until the 1990s. A more modern and the last one established on the basis of purely morphological approaches is that of Ponder & Lindberg (1997). The current system is phylogenetically oriented and goes back to Bouchet & Rocroi (2005).

The Thecosomata used to belong to the group of pteropods ( Pteropoda ) that existed well into the 20th century . At the end of the 19th century the Pteropoda formed an order of the Gastropoda, and at the beginning of the 20th century even a separate class of molluscs. In more modern taxonomies they form a subordination or have a comparable rank.

Systematics according to Bouchet & Rocroi (2005)

• Class Gastropoda G. Cuvier, 1797
  • Klade Heterobranchia JE Gray, 1840
    • informal group Opisthobranchia H. Milne Edwards, 1848
      • Klade Thecosomata HDM de Blainville 1824
        • Superfamily Cavolinioidea JE Gray, 1850 (1815)
          • Family Cavoliniidae JE Gray, 1850 (1815)
          • Limacinidae Costa family , 1873
          • Family † Sphaerocinidae Pelseneer, 1886
          • Family Pneumodermatidae PA Latreille, 1825
        • Superfamily Cymbulioidea JE Gray, 1840
          • Family Cymbuliidae JE Gray, 1840
          • Family Desmopteridae Chun, 1889
          • Family Peraclidae Tesch, 1913

The Pneumodermatidae family changed from the Gymnosomata to the Cavolinioidea superfamily .

Systematics according to Ponder & Lindberg (1997)

• Class Gastropoda G. Cuvier, 1797
  • Subclass Orthogastropoda WF Ponder & DR Lindberg, 1995
    • Subclass Apogastropoda L. Salvini-Plawen & G. Haszprunar, 1987
      • Superorder Heterobranchia JE Gray, 1840
        • Group Euthyneura JW Spengel, 1881
          • Order Opisthobranchia H. Milne Edwards 1848
            • Suborder Thecosomata HDM de Blainville, 1824
              • Partial order Euthecosomata
                • Superfamily Cavolinioidea JE Gray, 1850 (1815)
                • Superfamily Limacinoidea JE Gray, 1840
              • Partial order Pseudothecosomata
                • Superfamily Cymbulioidea JE Gray, 1840
                • Superfamily Peraclidoidea

literature

• AWH Bé and RW Gilmer: A zoogeographic and taxonomic review of euthecosomatous pteropoda. In: Oceanic Micropaleontology. Vol. 1. ATS Ramsey (ed.). Academic Press, London 1977, ISBN 978-0-125773-01-0 , pp. 733-808.
• S. van der Spoel: Euthecosomata, a group with remarkable developmental stages (Gastropoda, Pteropoda). J. Noorduijn (Thesis University of Amsterdam), Gorinchem 1967, 375 S., 17 tabs, 366 figs, OCLC 927599049 .
• S. van der Spoel: Pseudothecosomata, Gymnosomata and Heteropoda (Gastropoda). Bohn, Scheltema & Holkema, Amsterdam 1976, 484 pp., 246 figs, ISBN 978-90-313-0176-8 .

Web links

Commons : Thecosomata  - collection of images, videos and audio files

Individual evidence

1. ^ Thiele, J. (1929-1935). Manual of systematic molluscology. 2 volumes. 1-1154.
2. ^ R. Bieler & PM Mikkelsen (Sci.Ed.); JS Bhatti (Transl.); J. Thiele : Handbook of systematic molluscology. English: Handbook of systematic malacology. Publ: Washington, DC; Smithsonian Institution Libraries; National Science Foundation; 1992-. Content: pt. 1. Loricata; Gastropoda: Prosobranchia - pt. 2. Gastropoda: Opisthobranchia and Pulmonata - pt. 3. Scaphopoda / Bivalvia / Cehalopoda - pt. 4. Comparative Morphology / Phylogeny / Geographical Distribution. OCLC 680545970 .
3. ^ Ponder, WF & Lindberg, DR (1997). Towards a phylogeny of gastropod molluscs: an analysis using morphological characters . In: Zoological Journal of the Linnean Society. 119 (2): 83-265. doi : 10.1111 / j.1096-3642.1997.tb00137.x .
4. ↑ Bouchet, P. & Rocroi, J.-P .: Part 2. Working classification of the Gastropoda. In: Malacologia. 47: 239-283; Ann Arbor 2005; ISSN  0076-2997 , archive.org , ConchBooks, ISBN 978-3-92591972-5 .
5. ↑ Bouchet, P. & Rocroi, J.-P. (Ed.): J. Frýda, B. Hausdorf, WF Ponder, Á. Valdés & A. Warén (2005). Classification and nomenclator of gastropod families. In: Malacologia: International Journal of Malacology. 47 (1-2). ConchBooks: Hackenheim, Germany. ISBN 3-925919-72-4 . ISSN 0076-2997 . 397 p. Http://www.vliz.be/Vmdcdata/imis2/ref.php?refid=78278  
6. ↑ GT Poppe & SP Tagaro, February 23, 2006. The New Classification of Gastropods according to Bouchet & Rocroi, 2005. PDF ( Memento of the original from September 27, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked . Please check the original and archive link according to the instructions and then remove this notice.