Xerolenta obvia

White heath snail ( Xerolenta obvia )

The White heath snail ( Xerolenta obvia ), also called Eastern heath snail, is a species of snail from the family of deciduous snails ( Hygromiinae ) in the order of snails ( Pulmonata ). The nature tends to mass occurrence.

Features

The housings are of medium size (7-10 mm high, 14-20 mm wide) with a shallow thread. In the adult stage are 5 to 6 turns available that increase uniformly. The last turn is very low lowered relative to the axis of coiling of the previous whorls. The seam is weak. The umbilicus is relatively long, and takes about 1/4 of the housing diameter a. The mouth is slightly elliptical, the edges are not thickened. The mouth rim is slightly oblique to the axis of coiling. The shell is usually thick and the color white or yellowish white. Most individuals have to strongly variable, dark brown to almost black bands and the housing periphery, which could be resolved but also in band- like arrangement of spots. The soft body is yellowish brown with darker antennae.

Occurrence, lifestyle and dissemination

The species lives mainly in dry and open habitats such as steppes, dry grassy slopes and loose bush vegetation that can often have very high summer temperatures. They eat fresh and dry plant material. The animals lay in the summer often a dry rest and close their case having a calcareous diaphragm. In this state, it may be months without moisture and nourishment to survive. You're looking at no hiding place, but attach themselves to plants and stones. They can occur in such habitats in huge masses. The distribution ranges of Asia Minor, on the Balkan Peninsula to Central Europe to the Baltic Sea. The western border in Germany lies approximately on a line Heidelberg Lübeck. In France, there are some isolated occurrences such as in the Perigord. In the Alps, the type to be encountered at 2000 m altitude. She has since been deported to North America

Parasites

The populations of the white heath snail are often infected to a high degree with cercariae of the lancet or small liver fluke. The screws take the eggs, where already fully developed miracidia ( eyelashes larvae) are, with food on. From the miracidia form first sporocysts 1st order, the vegetative develop into sporocysts and 2nd order which in turn produce cercariae vegetatively. Are the cercariae fully developed, they migrate into the respiratory cavity of the screw. The snail slime forming small balls with a diameter up to 2 mm and closes the cercariae in the mucus one. These slime balls can contain up to 400 cercariae and are excreted by the worm from the respiratory cavity, respectively. The slime balls are eaten by ants, where the parasite is developing into metacercariae. If the ant picked up by a definitive host ( herbivore mammals), the metacercariae migrate into the bile ducts and trigger Dicrocoeliose from. The snails survive infection with the liver fluke small and can for 2 years produce and excrete cercariae.

System

The case of the white heath snail are very variable. Therefore, the species has been described under several different names: Helix candicans L. Pfeiffer, 1841, Helix dobrudschae Kobelt, 1877 (some still accepted as a subspecies ), Helix interpres Westerlund, 1879 and Helix kroli Clessin, 1879 This species was once common in the. genus Helicella provided. Today, this former much more extensive genus is divided into several distinct genera. The White heath snail is the typical species of the genus Xerolenta Monterosato, in 1829.