The molluscan genus Limax, or keel-backed slugs, is comprised partially of two of the
world’s largest terrestrial snails. the leopard slug (Limax maximus) and the the black keel back slug (Limax cinereoniger). Despite the names, the black keel-backed slug is the larger of the two, sometimes attaining a length of 20cm. The slightly smaller leopard slug rarely exceeds 13cm.
Their descent from shelled snails can be seen in the remnants of their small internal shell, in which they resemble their cephalapod relatives, the cuttlefish.
Most terrestrial slugs are hermaphrodites and in some instances can be self fertilizing. Here, however, we have an example of a pair of breeding leopard slugs, in all their sluggish glory.
While some people consider leopard slugs to be pests, there is contradictory evidence of this.
In general, leopard slugs are active at night, though they may also be seen in daytime during wet, warm and overcast weather. Usually they sleep under stones, rubble, deadwood, such as tree trunks and shelves, as well as in dark wall crevices. To feed they come out, and then can be found on mushrooms, withered plants and on algae growing on trees and stones. Partially Limax maximus is a carnivore, that also feeds on carrion, but also on other slugs and their eggs. Leopard slugs have even been observed to lead to a decrease of harmful slug species. So even if Limax maximus sometimes feeds on garden plants, it should not be called a garden pest, which it can only be in great numbers of overpopulation.
One does not usually think of slugs as beautiful or sensuous, but with the BBC’s photography and the narration of Richard Attenborough, Limax sex is amazing.