Partula snail
Scientific name: Partula affinis
Country: French Polynesia
Continent: Oceania
Diet: Algae, leaves
Food & feeding: Herbivore
Habitats: Tropical rainforest
Conservation status: Critically Endangered
Relatives: Giant clam, octopus
Description: Partula snails are small spiral-shelled land snails, rarely more than 20 mm long. Like other snails, they can retract their bodies inside their shells. They move using waves of muscular activity in their single foot. The foot glides over the surface of leaves on a layer of slime that is produced by a gland at the front end of the foot. They have dozens of tiny teeth, embedded in a strip of flesh in the mouth called the radula. The radula acts like a file, grinding their food from the surface of the leaves.
Lifestyle: They spend their time grazing algae from the surface of leaves in the forests on the small islands of the Pacific Ocean. They are most active after rain.
Growing up: Partula snails give birth to live young, whereas most snails lay eggs. It takes longer to produce live young, so these animals cannot reproduce fast enough to keep up with the rate the introduced predatory snail is eating the adults and this is another reason why many Polynesian tree snail species (including some Partula snails) have become extinct.
Conservation news: The story of Polynesian tree snails, such as the Partula, is a sad one. African land snails were introduced to the islands as a source of food for the local people, but they soon escaped and started eating crops. In 1974 , in an effort to control the land snails, a smaller predatory species of snail was introduced; Euglandina rosea. This species started to feed on the native Polynesian tree snails. Before long, many species of Polynesian tree snails became extinct. Out of an original 125 species in 3 genera (including Partula), 50 species are now extinct in the wild, and 24 survive in captivity.
Six species of tree snail are being kept at Bristol Zoo Gardens, all of which are part of a captive breeding programme. Some snails bred in Bristol have been released onto their island home in the Pacific. The captive breeding programme is coordinated by the Zoological Society of London.
In the islands of French Polynesia, dozens of different species of tree snail used to live alongside one another. Some lived only in trees of a certain species, others lived only on a single island. Each snail became specialised for a particular island, forest or species of tree. This process of specialisation, called 'adaptive radiation', is of great importance for the study of evolution.
