Crown snails

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Crown snails
Melanoides tuberculata

Melanoides tuberculata

Systematics
Class : Snails (gastropoda)
Subclass : Orthogastropoda
Superordinate : Caenogastropoda
Order : Sorbeoconcha
Superfamily : Cerithioidea
Family : Crown snails
Scientific name
Thiaridae
Troschel , 1857

Thiaridae (of Tiara , "Pope's Crown") to German also thiaridae called, are a family in the fresh water of live snails order sorbeoconcha that have their habitat in tropical regions. There are about 110 known recent species .

features

The small to medium-sized snails have a slender to conical, usually no more than 4 cm long, usually yellow to red-brown shell , often with a flamed or spirally banded pattern. Due to the elongated pointed shape of the shell, the apex of these snails is often worn out. The ganglia of the nervous system are more concentrated in the head than other groups of snails.

Reproduction

Crown snails are separate sexes, but many species of this family reproduce parthenogenetically , which is why there are only females in these species. The offspring are created from unfertilized egg cells, so that no male is required for reproduction. A search for a partner is therefore not necessary, the process of reproduction and thus the spreading is faster than with sexual reproduction. In addition, the females of the Thiaridae have a special breeding bag in which they hold back both eggs and the developing young as fully developed, small snails until they hatch.

Occurrence and distribution

Crown snails are found in tropical rivers and lakes in Central America , South America , Africa and Asia as well as on the Caribbean and Pacific islands.

Use and meaning for humans

The coniferous crown snail ( Melanoides tuberculata ) native to fresh waters of the Indo-Pacific region is one of the most common snails kept in aquariums . In this way it was introduced as an invasive species to areas on the Gulf of Mexico , among others , where it is seen as an intermediate host for various flukes and a health problem for humans. Crown snails are also intermediate hosts for the transversotrema patialense scale worm, which parasitizes fish .

Systematics

According to the system of Bouchet and Rocroi (2005), the Thiaridae family, along with many other families, belongs to the superfamily Cerithioidea , within which freshwater was populated several times from the sea. According to Bouchet and Rocroi, the Thiaridae family has no subfamilies. There are the following types :

literature

  • Philippe Bouchet & Jean-Pierre Rocroi: Part 2. Working classification of the Gastropoda . Malacologia, 47: 239-283, Ann Arbor 2005 ISSN 0076-2997
  • Matthias Glaubrecht: Evolutionary ecology and systematics using the example of freshwater and brackish water snails (Mollusca: Caenogastropoda: Cerithioidea): ontogenesis strategies, paleontological findings and historical zoogeography . Backhuys, Leiden 1996. pp. 200ff. On the question of the monophyly of the Thiaridae .
  • Peter Glöer: Freshwater gastropods in Northern and Central Europe: key to identification, way of life, distribution . ConchBooks, Harxheim 2002. S. 74. Order Neotaenioglossa HALLER 1892: Family Thiaridae TROSCHEL 1857 (1823) . ISBN 978-3925919602
  • Usa Klinhom: The Thiaridae (Prosobranchia: Gastropoda) of Thailand: Their Morphology, Anatomy, Allozymes and Systematic Relationships . Mahidol University, Bangkok 1989.
  • Brian John Smith, Ronald Calder Kershaw: Field Guide to the Non-Marine Molluscs of South Eastern Australia . Australian National University Press, Canberra 1979. p. 57. Thiaridae .

Web links

Commons : Crown snails  - Collection of images, videos, and audio files