Theba Pisana - Ecology

Ecology

Theba pisana usually lives in coastlands, in or near sandy habitats. In hot climates it aestivates often directly exposed to the sun, attached to grasses, shrubs or succulent plants, fence posts, tall weeds, and so on. It is common near beaches. In dunes it can live on nearly bare sand that is poorly fixed in place by grasses. In colder regions the snails do not aestivate, but they do climb on plants in dry weather. This snail does not survive serious winter frosts.

Theba pisana is often associated with two other land snail species Cochlicella acuta and Cernuella virgata, but it can live slightly deeper inside pure sandy habitats, and is usually more common than Cochlicella acuta. It is one of the most common snails in coastal regions from south Portugal to Greece.

In South Africa, a study showed that these snails were most abundant along roadsides; densities decreased dramatically with distance from roads. These snails were observed on a wide variety of endemic and introduced plant species, and appeared to have a catholic diet. Theba pisana is also a significant pest of citrus, vines, legume crops and cereals in South Africa. In Australia, it feeds on a range of agricultural plants.

in Britain and France, Theba pisana has an annual life cycle, breeding in summer and autumn, while in the Mediterranean, they have a biennial life cycle with breeding in autumn and winter. In South Africa, Theba pisana appear to have an annual lifecycle, breeding in autumn to winter and growing to adult size of about 14 mm diameter by the end of the following summer. Maturity is reached at half maximum shell size after 1 year. Maximum shell size is attained after 2 years. This species of snail makes and uses love darts. The size of the egg is 2.2 mm. In South Africa, the population density can reach up to 300-700 snails m².

In South Africa, these snails are active mostly at night and especially during periods of high humidity, irrespective of temperature.