Natalina cafra

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Natalina cafra
Housing by Natalina cafra, Amsterdam Zoological Museum

Housing by Natalina cafra , Amsterdam Zoological Museum

Systematics
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Superfamily : Rhytidoidea
Family : Rhytididae
Genre : Natalina
Type : Natalina cafra
Scientific name
Natalina cafra
( Férussac , 1821)

Natalina Cafra is a predator living snail from the family Rhytididae in the subordination of terrestrial snails (gastropod), which in South Africa is widespread and has undesirable herbivorous for humans as predator snails importance.

features

The closely genabelte, spherical depressed, rippenstreifige, very thin and fragile, large to very large shell of Natalina Cafra is greenish and has irregular olive colored stripes. The thread, which is blunt at the top, stands out as a short cone. In the adult snail, the shell has five moderately arched coils, the last of which is widened towards the front and slightly depressed. The slightly oblique, wide and oval case mouth has a moderate cutout. The sharp, straight edge of the mouth, the edges of which are connected by a thin callus, is slightly surmounted by the periostracum . The edge of the spindle is broadly bent and partially covers the navel. The house is 73 mm wide and 50 mm high, the opening 49 mm wide, 45 mm long and 39 mm high. The case diameter of very large examples was up to 75.7 mm, but it is rarely more than 65 mm. The protoconch is typically 7 to 8 mm in diameter.

Due to its very thin layer of lime compared to the periostracum, the snail shell disintegrates - similar to other Rhytididae - after the snail dies when it is exposed to dry air.

The snail is gray or grayish-brown to dark orange-brown on the head and foot, darker on the back and usually also on both sides with a paler stripe that runs backwards from the base of the respective eye feeler. The antennae and the well-developed labial palps are darker gray-brown. The skin surface is finely grained. The rear part of the foot is flat and triangular, the tip of the tail tapering to a point. The edge of the coat is often orange to orange-brown. The epiphallos has a well-developed bulla on the outer wall next to its mouth in the vas deferens .

The tooth formula of the radula of Natalina cafra is 1 + 5 + (20–30) in a total of four examined radulae up to 53 mm long with up to 57 transverse rows of teeth. A young animal with a shell diameter of 12.5 mm had a 12 mm long radula with 47 rows of teeth and a tooth formula of 1 + 5 + 10. Longer radulae of older animals are up to 58 mm long with 80 transverse rows of teeth. The outermost lateral teeth are very large, but all marginal teeth are stunted, while there are no medium-sized teeth between the lateral and marginal teeth.

The radula teeth are sharp enough not only to cut up captured snails and earthworms. The South African malacologist Markus Lussi reports that a snail, which he picked up from the lawn, inflicted a 5 mm long bleeding wound on his thumb with its radula in a lightning-fast movement. The muscles in the mouth area are very strong, so that a large Roman snail is completely eaten in a few days.

Distribution and occurrence

Natalina cafra is common in the South African provinces of KwaZulu-Natal and East Cape . It tolerates relatively dry environments and occurs in different types of vegetation of the scrubland of Albany on, including the fynbos on the coast, Strandveld , grass rich fynbos mountains, Bontveld , thornveld , various types of thickets, coastal forest and suburban gardens. It lives in leaf litter under bushes and bush vegetation, under rocks, fallen aloe plants or dense tufts of grass. It is common here, but in low density and most common on limestone such as in Grassridge north of Port Elizabeth in the Alexandria Formation.

Life cycle

Like other lung snails, Natalina cafra is also a hermaphrodite , in which the partners exchange their sperm during mating. Sexual intercourse, including foreplay, lasts less than an hour. One sexual partner crawls onto the other's house and with his mouth caresses the neck of the other, who is holding his head towards him. The roles can be swapped after a short sexual act of barely 10 minutes. Since Natalina cafra does not mate from foot to foot, unlike, for example, Roman snails and most other lung snails, only one-sided mating and fertilization with male and female roles is assumed as a rule, but there is also mutual penetration of the penises in the sex position on the shell into the partner's vagina.

Ideally, both partners lay their eggs soon after mating, which have a whitish, soft shell with tightly packed tiny lime crystals in a flexible matrix and are around 10 to 16 mm long and 8 to 12 mm wide. When the young snails hatch, in addition to the protoconch of the snail shell, a quarter of the teleoconch has already been formed.

nutrition

The predator snail Natalina Cafra preferred as other species of the genus in particular other housing-bearing worm as prey and eats addition also slugs and earthworms . The victim is grasped with the radula and either put into the mouth as a whole or, in the case of larger prey with a casing, first cut up with the help of the sharp radula teeth and picked up in small bits and then grated in the foregut. The preferred snails to eat include Achatina immaculata , Cornu aspersum and the nudibranch Elisolimax flavescens .

Natalina cafra can drag an empty snail shell with her on the back of her foot for up to 3 days in order to extract the lime from it.

Due to their predilection for snails as prey, the Natalina predatory snails in South Africa are colloquially referred to as cannibal snails and Natalina cafra as common cannibal snail (" common cannibal snail ").

Systematics

Natalina cafra was first described in 1821 by André Étienne d'Audebert de Férussac as Helix (Helicophanta) cafra .

literature

Web links

Commons : Natalina cafra  - collection of pictures, videos and audio files

Individual evidence

  1. ↑ a b O. von Möllendorff: Agnatha Moerch. Predator snails. 4. Genus Natalina Pilsbry, 1. Natalina caffra (Fér.) , Pp. 20f. In. O. von Moellendorff and Wilhelm Kobelt: The predatory lung snails (Agnatha). Systematic Conchylia Cabinet by Martini and Chemnitz. Verlag von Bauer and Raspe (Emil Küster), Nuremberg 1905.
  2. ↑ a b c D. G. Herbert, A. Moussalli (2010), p. 33.
  3. ^ A b David Herbert, Dick Kilburn: Field Guide to the Land Snails and Slugs of Eastern South Africa. Natal Museum, Pietermaritzburg 2004. p. 217. ( Snippet: person injured by Natalina cafra )
  4. ↑ DG Herbert, A. Moussalli (2010), pp 15f.
  5. ↑ DG Herbert, A. Moussalli (2010), pp. 30–35.
  6. ↑ DG Herbert, A. Moussalli (2010), p. 10
  7. ↑ DG Herbert, A. Moussalli (2010), p. 11
  8. ↑ DG Herbert, A. Moussalli (2010), p 7f.
  9. ^ DG Herbert (1991): South Africa's carnivorous snails. African Wildlife 45 (1), pp. 6-11.
  10. ^ David Herbert, Dick Kilburn: Field Guide to the Land Snails and Slugs of Eastern South Africa. Natal Museum, Pietermaritzburg 2004. p. 217.
  11. ^ André Étienne d'Audebert de Férussac : Tableaux systématiques des animaux mollusques classés en familles naturelles, dans lesquelles on a établi la concordance de tous les systèmes: suivis d'un prodrome général pour tous les mollusques terrestres ouviatiles ouviatiles ouviatiles ouviatiles or fossils. Deuxième partie (première section). Tableaux paticulières des mollusques terrestres et fluviatiles, present for chaque famille les genres et espèces qui la composent. Class des gastéropodes. Order des pulmonés sans opercules. II. Tableau de la famille des limaçons. Arthus – Bertrand, Paris 1821–1822.