The term 'slug' refers to a body type and not a group of closely related animals. The slug form has evolved several times in both land and marine molluscs.
A Leopard Slug, Limax maximus
Photographer: Alan Henderson / Source: Museum Victoria
Land snails and slugs belong to the Phylum Mollusca, the second-largest Phylum in the animal kingdom. They are all gastropods, and the slugs are all included in the order Pulmonata. In slugs, the shell that is so typical of most molluscs is lost or reduced to a small remnant buried in the soft tissue. The long, soft body of the slug is unsegmented and has tentacles on the head. It is capable of occupying very small spaces.
Distribution and habitat
Approximately 11 species of land slugs are found in Victoria. Most are introduced from Europe, however two native species, Cystopelta purpurea and Cystopelta astra, occur in forest & woodland areas of Victoria.
Slugs are generally found in cool, damp situations, with the introduced species preferring man modified areas, such as cultivated gardens and areas planted with crops and pasture. Because they have no shell, slugs are very susceptible to desiccation.
Most slugs feed on living plants, but some also eat decaying vegetable matter, and some will eat almost anything, including dog faeces and dog food. Some are regarded as serious pest in gardens, crops and pasture. Slugs are hermaphrodites and many species have complex courtship behaviour.
Barker, G. M. 1999. Naturalised Terrestrial Stylommatophora (Mollusca: Gastropoda). Fauna of New Zealand, volume 38. Whenua Press, New Zealand.
Beesley, P. L. et al. (eds) 1998. Mollusca, the Southern Synthesis. Fauna of Australia, volume 5. CSIRO Publishing, East Melbourne.
Runham, N. W. and Hunter, P. J. 1970. Terrestrial Slugs. Hutchinson University Library, London.
Smith, B. J. 1979. Field Guide to the Non-marine Molluscs of South-eastern Australia. ANU Press, Canberra.
Smith, B. J. 1992. Non-Marine Mollusca. In Houston, W. W. K. (ed.) Zoological Catalogue of Australia. Canberra: AGPS Vol. 8.