Distribution: Uncommon in the Solitary Islands Marine Park. Distributed throughout the tropical Indo-Pacific region, from Mozambique and East Africa to the Solomon Islands and Fiji, north to Sulawesi, south to Australia. In Australia recorded from around Shark Bay in Western Australia, across the tropical north, the Coral Sea and Great Barrier Reef in Queensland south to northern New South Wales.
Ecological Notes: Frequent rocky and coral reefs, depth from intertidal to at least 15 m.
Additional Notes: Characterised by the the dark colouration and longitudinal yellow lines which sometimes may be obscure or represented by a line of yellow or orange dots. These lines consist of a series of glandular pits which secrete a yellow substance if disturbed. The rhinophores appear outsized for the animals body, as do the rolled oral tentacles visible in this photograph. The oral tentacles are believed to be used to follow the mucus trail of its prey. Diet is not certain but it is believed members of this genus prey on other ophistobranchs. Grows to around 25 mm.
References: Australian Museum, Sea Slug Forum. http://www.seaslugforum.net/find/5368. Accessed 22/09/2019.
Atlas of Living Australia website at https://bie.ala.org.au/search?q=roboastra+gracilis. Accessed 22/09/2019.