A Field Guide to the Snails of Lord Howe Island

6 the inside back cover. To simplify the description of geographic ranges, we have subdivided the island into four regions (see map on p. 4): • the North Bay region (including North Bay, Mt Eliza, Malabar, Kim’s Lookout and Old Settlement), • the Settlement region (including Lagoon Beach, Transit Hill, the Clear Place, Valley of the Shadows, Middle Beach and Steven’s Reserve), • the Intermediate Hill region (including Intermediate Hill slopes and summit, Johnsons Beach, Blinky Beach, Rocky Run and Boat Harbour), • the Southern Mountains (including the Mt Lidgbird and Mt Gower summits and slopes). Land snail biology Snails and slugs belong to the phylum Mollusca, which is one of the largest animal groups, second only to the arthropods (insects, spiders, crustaceans and their relatives). As well as the slugs and snails, collectively known as the gastropods, other mollusc groups include bivalves, cephalopods (octopus and squid) and chitons as well as several smaller groups. The majority of molluscs are marine species, but there have been several independent invasions of freshwater and terrestrial environments. Approximately one third of all extant gastropods live in terrestrial habitats (MolluscaBase, 2020). Land snails are very diverse and are found in a broad range of habitats. Some species are still partially dependent on aquatic environments and are found in mangroves or the intertidal zone. There are species adapted to desert conditions that are able to survive long periods without water, and high montane species that survive in freezing temperatures. A huge diversity is found in tropical rainforests, some living exclusively on trees and others in the leaf litter or under logs. Many snail species are associated with limestone-rich areas, and some are specialists who live directly on rock faces. Shell reduction and loss has also evolved multiple times, giving rise to numerous lineages of slugs and semislugs. The majority of land snails graze on biofilm (made up of fungi and other micro-organisms) in leaf litter or on tree trunks and leaves. Other species are carnivorous and feed on other snail species or earthworms. Many land snails, but not all, are hermaphroditic. Most are egg-layers, but some give birth to live young.