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Helix pomatia(Linnaeus,1758)

Description:Shell spherical with a conical spire,very strong with thin axial lines.The aperture is round and the lip thin. The umbilicus is narrow and covered by the edge of the columella in a way that leaves only a slitlike opening visible.In some cases the umbilicus is completely covered. In old shells the periostracum is often worn away giving the surface a whitish color. There are 4.5-5 whorls,shellsize is 32-50 mm wide and 30-50 mm high. The color is light yellowish brown to whitish grey,often with 3 faint mauve or dark violet bands. Habitat:Copses,thickets,parks,gardens and vineyards.The snail prefers a chalky substrate in warm low lying country. Distribution:Orginally from Central- and Southeast Europe this species has spread out towards other areas mainly by human hands. From South-Denmark southwards to Central-Italy,westwards to France and Southern England, eastwards to Russia(Riga).It has been introduced in the USA as well(Michigan). In some areas(especially France)overcollecting has greatly diminished the numbers of H.pomatia.In some countries in Europe this species has been put on the Red list of endangered animals.

The shell The shell is big enough for the snail to retract the whole body in it.It usually has 4-5 whorls which coil clockwise as the snail grows.The axis of the shell is called the columella,attached to this is a muscle which runs through to foot to the tentacles. The snail builds his shell by secretion of calciumcarbonat from the mantle. A thin layer,called the periostracum,covers the outside of the shell.In adult snails this is often weathered and flaking off. Because Vineyard snails often crawl on walls and trees,accidents happen and they fall off.That is why you often see shells with rough patches on it,the snail is able to repair the shell very quickly.

Slime Slime or mucus has different functions for a snail and can be thin or thick. It is an organic hydrogel which can absorb a great quantity of water,almost 250 % its on weight.On the body there are glands which run from the mouth to the backend. Slime helps prevent waterloss,is used in locomotion by enabling them to crawl over rough surfaces or slick ones(glass).It is also used as a deterrent against enemies, although the slime itself doesn't contain any bitter tasting chemicals.

Locomotion There are two sets of muscle fibers,each performs a different task.When moving forward one set contracts pulling the snail from the front and pushing it off toward the back. At the same time the second set pulls the outer surface of the sole forward.

Body:digestion On the front of the body is the head,where two pairs of tentacles are located. The upper pair bearing the eyes,the lower pair is being used for smelling and feeling. The mouth has a tongue called radula.In the top of the mouth is a hard ridge and food is being mashed between the radula and this ridge.The front teeth of the radula wear very fast but the radula grows from the backend. Near the opening of the mouth salivary glands release digestive enzymes.The salivary glands secretions moisten the digested food and envelop them,thereby making easier it for the food to go into the oesophagus. The oesophagus ends in the stomach.The intestines release large quantities of a brown digestive juice in the stomach.The intestinal gland fills up most of the space in the visceral sac.The intestinal gland consists of smaller and bigger follicles.A steady back and forth movement of the digestive juices between stomach and intestines enhances the process of absorption of the food.The movement of the digestive juices is caused by the muscles of the intestinal gland and ciliae. The digested food flows over the livercells which absorb the food. The smaller intestine starts at the visceral sac it follows the edge of the kidney and enters the pulmonary cavity.It ends near the pneumostome(breathing pore). In the smaller intestine is on the point of exit from the visceral sac a deep groove.This groove which is coated with cilae takes over all non-absorbed solids and directs it into the small intestine. There the solids are compressed and enveloped with a layer of slime after which they leave the body. The kidney of the Vineyard snail lays as a yellowish,trangular,organ in the rear segment of the lung.One of the sides of the kidney runs parallel to the intestine,the other side is arranged closely to the pericard.The kidney consists of two parts:the kidney cavity where the excrements are secreted and the primary urethra,in which the first part of the discharge of the excrements takes place. This goes then to a second segment,the secondary urethra,where it leaves the body.

Body:respiration and blood circulation The blood system in Helix pomatia is open,with blood spaces and no veins. The pigment is colorless,and is called haemocyanin,which contains copper. The relative weak heart consists of a single thick walled ventricle and a single thin walled auricle.The blood takes oxygen from the lung and transports it to the auricle,and then to the ventricle. The ventricle releases blood with oxygen in the arteries,after which the blood goes to the tissues. The so-called lung(pulmonary cavity) lays on the inside of the roof of the visceral-sac. Through the breathing-pore,the pneumostome,oxygen reaches the snails lung. When the pneumostome is open the roof and bottom of the pulmonary cavity are close together.When the bottom goes down the oxygen can flow into the lung. Then the pneumostome closes and the bottom goes up,pushing the oxygen in the body.It is comparable to the midriff in mammals.

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