Snail Zone

Life in the Slow Lane: The Brown Garden Snail

Perhaps the most widely known member of the mollusk group, the brown garden snail (Cornu aspersum), also known as the European garden snail, is native to the Mediterranean region of southern Europe and northern Africa, and his since spread to every continent except Antarctica. It thrives in temperate zones, particularly in open forests, coastal dunes, and urban parks and agricultural spaces. This spread has largely been facilitated by humans, and may have started as early as the Neolithic era nearly 8500 years ago.

The brown garden snail's name is an excellent descriptor of the species; both the body and the shell are mainly shades of brown. Generally the body is lighter than the shell, and secretes a thin layer of mucus to keep itself moist. The shell is about 2.5 to 4 cm (0.98-1.57 in) wide, while the body itself is roughly 5-9 cm (1.97-3.54 in) long. Body and shell combined, C. aspersum only weighs 15g (0.53 oz) at maximum. The body is made of two parts; the head, which carries the eye stalks, mouth, and sensory tentacles; and the foot, essentially a large muscle which the snail uses to move from place to place. The rest of its organs, including the heart, lungs, stomach, and anus are contained within the shell itself. Only the genital pore, located on the side of the foot, is exposed.

C. aspersum is primarily an herbivore, feeding on leaves, flowers, and fruits, as well as rotting plant and animal matter. In order to obtain the calcium it needs to build and maintain its shell, the European garden snail also occasionally consumes soil. Because of its slow nature, reaching a maximum of only 2.4 mm/s (0.09 in/s), this species is a common food item for other predatory snails, centipedes, glow worms, small mammals, lizards, frogs, and birds. However, the brown garden snail is able to retreat into its shell and produce a thick, frothy mucus membrane when threatened.

Like other terrestrial mollusks, the European garden snail is a hermaphroditic species, possessing both male and female gametes. Individuals may reproduce year round, provided with plentiful resources and good environmental conditions. When two snails encounter each other and wish to mate, each one spears the other with a hard calcite spine, known as a love dart. These darts allow the two to exchange sperm, and the process may take several hours. Afterwards, an individual may store viable sperm for up to 4 years. About ten days after a snail fertilizes its sperm, it lays about 50 eggs in a sheltered area; a single snail may do this up to 6 times a year. Eggs take between 2-4 weeks to hatch, and emerge with a soft shell. It takes about 10 months for juveniles to reach full maturity, and they may live up to 3 years in the wild.

Conservation status: C. aspersum has been rated as Least Concern by the IUCN. In both its introduced and native range, it is considered a pest species due to its consumption of crops. However, this species has also been adopted in some areas as a pet or as an edible delicacy.

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Photos

Bill Frank

Alan Henderson

Kostas Zontanos