Land snails (Mollusca: Gastropoda) of India: status, threats and conservation strategies

The tropics have faced massive biodiversity loss due to intensive anthropogenic activities such as changes in land use and degradation of environment. Recent reports suggest that the tropics are losing biodiversity at an alarming rate (Sodhi 2008). Much of this biodiversity loss has been reported for vertebrates and plants. However, there is very little knowledge on the extent of loss in lesser known groups, especially the invertebrates. In this paper, we highlight the importance of land snails and the need for their conservation. Land snails include several distinct lineages of terrestrial gastropods and belong to the second largest phylum after arthropods in terms of number of species with more than one lakh described species (Lydeard et al. 2004). Land snails constitute about six per cent of the total species on Earth (Clark & May 2002). A large part of molluscan fauna in many tropical regions of the world is still poorly known. They form an important component of the forest ecosystem by recycling nutrients (Graveland et al. 1994; Dunk et al. 2004) and are the prey base for a number of small mammals, birds, reptiles, amphibians and other invertebrates, including carnivorous snails (Deepak et al. 2010). In calcium poor habitats land snails can form an important source of calcium for other animals. Land snails also serve as an indicator of ecological conditions, and are very sensitive to climatic and ecological change (Shimek 1930; Simone 1999; Čejka & Hamerlík 2009). Thus, they are useful for reconstructing past environments (Bar-Yosef Mayer 2002; Gümüş 2009). As early as 1839 Charles Darwin showed the value of land snails in studying environmental change (Naggs et al. 2006). Terrestrial snails prove to be Abstract: Land snails form an important component in the forest ecosystem. In terms of number of species, the phylum Mollusca, to which land snails belong, is the largest phylum after Arthropoda. Mollusca provide unique ecosystem services including recycling of nutrients and they provide a prey base for small mammals, birds, snakes and other reptiles. However, land snails have the largest number of documented extinctions, compared to any other taxa. Till date 1,129 species of land snails are recorded from Indian territory. But only basic information is known about their taxonomy and little is known of their population biology, ecology and their conservation status. In this paper, we briefly review status, threats and conservation strategies of land snails of India.