Distribution: Seasonally common and widespread in the Solitary Islands Marine Park. Recorded only from the South West Pacific, including Heron Island, Lord Howe Island, Norfolk Island and the east coast of Australia from southern Queensland to northern New South Wales.

Ecological Notes: Found on rocky reef to a depth of 25 m. Feeds on sponges, particularly Euryspongia sp.

Additional Notes: The background colour of the mantle and foot is translucent greyish often covered in part by opaque white. There is an open reticulation of thin dark brown to black lines surrounding yellow spots and patches. The tiled pattern on the mantle is distinctive as is the white spot on the tip of the reddish orange rhinophores. Mating pair at top, animal with egg mass in second photo. Grows to 35 mm.

References: Gary Cobb, David Mullins, Nudibranchs Encyclopedia, 2nd Edition, 2015. Publishers Thomas Slone, Masalai Press and Tim Hochgrebe, Underwater Australasia. p.145.

Australian Museum, Sea Slug Forum. http://www.seaslugforum.net/find/hypsjack. Accessed 24/09/2018.