Land snails

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Land snails
Beautiful land snail (Pomatias elegans)

Beautiful land snail ( Pomatias elegans )

Systematics
Subclass : Orthogastropoda
Superordinate : Caenogastropoda
Order : Sorbeoconcha
Subordination : Hypsogastropoda
Superfamily : Littorinoidea
Family : Land snails
Scientific name
Pomatiidae
Newton , 1891

The pomatiidae (Pomatiidae) are a living on the land snails - Family of order sorbeoconcha . The oldest representatives of the family appear in the Campan (Upper Cretaceous).

features

The housings are small to large, from about 4 mm to 60 mm in height. They are usually helicoid to tower-shaped, more rarely flattened or disc-shaped. The sculpture consists of spiral lines, which are mostly crossed by longitudinal ribs and lines. This results in a typical net-like pattern. The ribs can also be weaker or even absent. There are also almost smooth housings. The round, multi-spiral operculum consists of two calcareous layers and a system of micro-channels. It can be retracted deep into the housing. The outer layer is smooth or with a single spiral lamella. In some species a sexual dimorphism can also be seen in the housing. The females are slightly larger on average. In a few species, males and females also differ in the sculpture of the housing.

Like other Sorbeoconcha , the animals are of separate sexes, with the females usually being larger than the males. The head is extended to a distinct trunk ( proboscis ), which is not forked or only slightly bilobed. The animals have only one pair of antennae, and the eyes are at the base of the antennae. The sole of the foot is divided into two zones lengthways by a furrow. In the radula , the central tooth has five tips, the posterior teeth with two different tips. The females produce relatively large egg capsules that are filled with lots of egg white. The embryos feed on this egg white. The development time for some species is very long; ready-made small animals hatch from the egg capsule.

Due to the longitudinal division of the sole of the foot, the locomotion of land snails differs considerably from the locomotion type of land snails ( Stylommatophora ). These move forward through wave-like movements of the sole of the foot perpendicular to the longitudinal axis of the animal. The representatives of the terrestrial snail alternately move the left and right half of the foot forward and thus move forward in a kind of walking gait.

Unlike other aquatic Sorbeoconcha, there are no gills. Breathing takes place through the mantle cavity, which is formed as a lungs analogous to the pulmonary snail and is permeated by fine blood vessels. As with other Sorbeoconcha, but in contrast to the pulmonary snails an osphradium is present.

Geographical distribution

The range of the family is disjoint. The north-western area extends from the warmer areas of Western Europe (in the north to the British Isles and Ireland), across southern Europe, individual occurrences in Germany and Denmark ( beautiful land snail Pomatias elegans , more often only in the Upper Rhine area, e.g. Isteiner Klotz ) , North Africa to the Middle East, the coasts of Asia Minor to the Caucasus and the southern coastal areas of the Caspian Sea. The second area extends from the south-western coastal areas of the Arabian Peninsula, the Horn of Africa, Socotra, along the East African coasts and Madagascar, including from Mauritius to South Africa. A third, smaller area is located on the Indian subcontinent ( Maharashtra , Tamil Nadu , Nilgiri Mountains ).

Taxonomy

Bouchet & Rocroi (2005) divided the family Pomatiidae into two subfamilies, Pomatiinae and Annulariinae Henderson & Bartsch, 1920. The latter, however, is now regarded as an independent family Annulariidae . Neubert (2010) divides the family, which is somewhat reduced in size, into the subfamilies Cyclotopsinae Kobelt & Möllendorff, 1898 and the nominate subfamily Pomatiinae. Synonyms are: Cyclostomatidae Menke, 1828 and Ericiidae Wenz, 1915. The following genera are currently included in the Pomatiidae family.

supporting documents

literature

  • Eike Neubert: The continental malacofauna of Arabia and adjacent areas. VI. Pomatiidae of Arabia, Socotra and Northeast Africa, with descriptions of new genera and species (Gastropoda: Caenogastropoda: Littorinoidea). Fauna of Arabia, 24: 47-127, 2009 PDF
  • Wilhelm Wenz: Gastropoda. Part I: General Part and Prosobranchia. In: Handbuch der Paläozoologie Volume 6, 948 p., Berlin, Verlag von Gebrüder Borntraeger, 1938 (p. 531)

Individual evidence

  1. ↑ a b c Klaus Bandel: Caenogastropoda during Mesozoic times. Scripta Geologica, Special Issue, 2: 7-56, Leiden 1993 PDF
  2. ↑ GT Watters: The Caribbean land snail family Annulariidae: A revision of the higher taxa and a catalog of the species. 558 pp., Leiden 2006.
  3. ^ Neubert (2009: p. 50)

Web links

Commons : Land snails (Pomatiidae)  - Collection of images, videos, and audio files