Warty Slug

• As well as the eyes on its head, it has accessory eyes on the papillae of its back, complete with retina and lens, which let it detect the shadows of predators from above.
• It is not a nudibranch despite its looks: it is a pulmonate, more closely related to land slugs than to sea slugs. It breathes air with a lung.
• Its eyes sit at the tips of two head tentacles, and it also has dorsal eyes scattered over its back, which is most unusual.
• It always returns to the same refuge. It comes out to feed at low tide and finds its way back along its own mucus trail; a 1981 study showed that the outward and return trails carry different information.
• When submerged it unfurls branched gill papillae from its tubercles that look like a nudibranch's gills, and only on picking it up does its pulmonate anatomy become obvious.

Habitat and environment

Tropical intertidal rocks and muds, including mangroves

Sources consulted: Cuvier (1830) · McFarlane (1981), Journal of Experimental Marine Biology and Ecology · Rudman, Sea Slug Forum