Moderately common in the Solitary Islands Marine Park. Widespread throughout the tropical Indo-West Pacific, in Australia recorded from Western Australia, Queensland and in New South Wales south to at least Jervis Bay.
Found on rocky reef areas. Feeds on sponges. Depth to at least 32 m.
Extremely variable in colour and pattern. Characterised by yellow ridges with yellow and brown lines in between. Black band around rhinophore club may also be an identifying feature. Grows to at least 80 mm in our region, reported up to 30 cm in tropical waters.
Gary Cobb, David Mullins, Nudibranchs Encyclopedia, 2nd Edition, 2015. Publishers Thomas Slone, Masalai Press and Tim Hochgrebe, Underwater Australasia. p.179.
Australian Museum, Sea Slug Forum. http://www.seaslugforum.net/find/halgwill. Accessed 24/09/2018.