The Great Barrier Reef and the wider Queensland coast are home to many kinds of sea slug. Here are ten nudibranchs you might come across, from a slug that can reach 60 cm to species only a couple of centimetres long. New to sea slugs? Start with our guide: what is a nudibranch?
How we chose these ten
Every species on this list has a documented record from Queensland waters: either a photo record in the Australian Museum's Sea Slug Forum or a preserved museum specimen listed in the Atlas of Living Australia. Scientific names follow the World Register of Marine Species (WoRMS), and we note older names you may see in field guides.
Ten nudibranchs of Queensland waters
1. Spanish dancer (Hexabranchus sanguineus)
The giant of the group. The Queensland Museum says it can reach 60 cm, although animals of 20 to 30 cm are more usual, and that it is usually orange-red with white dots. It lives on coral and rocky reefs in Queensland and across the Indo-Pacific. It can swim, and unusually for its group, its gills have no pouch to retract into.
2. Nembrotha kubaryana
A large, bold slug that can grow past 120 mm. It is essentially black with green bumps or green ridges, with a bright orange border around the foot, the rhinophore pockets and the mouth area. It feeds on sea squirts. The Sea Slug Forum includes a green-spotted animal photographed at North East Orpheus Island, North Queensland. You will find a Nembrotha design among our nudibranch tees.
3. Chromodoris elisabethina
One of several blue chromodorids with dark lines. Its background is blue or bluish white with black or dark blue lines running lengthways, and its gills, rhinophores and mantle border are usually orange or yellow. The Sea Slug Forum's example was photographed at Lizard Island, North Queensland. Its close look-alike, Chromodoris annae, has scattered dark specks in the blue and usually no central black line.
4. Chromodoris lochi
A translucent white or bluish-white slug with dark blue or black lines along the back. The giveaway is its plain gills and rhinophores, which range from translucent straw to dull orange or pink. The Sea Slug Forum shows one from Escape Reef on the Great Barrier Reef, north of Cairns.
5. Goniobranchus coi
Once known as Chromodoris coi. Its dull brown centre is outlined by a wavy purple line, with a thin purple line around the edge of the mantle. As it crawls, the whole mantle edge flaps rhythmically up and down. Sea Slug Forum photos come from Lizard Island, Queensland.
6. Hypselodoris bullockii
A good reminder that colour can vary within one species. It ranges from pale straw or white to deep purplish pink, usually with a thin white line around the mantle edge, and its gills and rhinophores are typically yellow or orange with a pink or purple band at the base. Sea Slug Forum photos come from Pelorus Island and Heron Island in Queensland. You may also see it spelt bullocki.
7. Hypselodoris tryoni
Formerly Risbecia tryoni. It belongs to a group of look-alikes with large purple or purple-brown spots, usually ringed with white, on a brownish, often net-patterned background, with a narrow purple line at the border. The Sea Slug Forum's Queensland example was photographed at 15 metres at Heron Island and measured 61 mm.
8. Doriprismatica atromarginata
Older guides call it Glossodoris atromarginata. It is creamy white to pale brown, with a black line along a very wavy mantle edge, black rhinophores and black-edged gills that often wave as it crawls. It grows to about 60 mm. Sea Slug Forum photos come from Heron Island and Pelorus Island, and museum specimens in the Atlas of Living Australia include animals collected at Alma Bay and Cockle Bay on Magnetic Island.
9. Phyllidiella pustulosa
A firm, bumpy slug. Its key features are three clusters of pink bumps (tubercles) down the middle of the back and a pale pink edge to the mantle, although the bumps can range from pink to green to white. The Sea Slug Forum shows animals from Pelorus Island, North Queensland, and the Atlas of Living Australia lists a museum specimen collected at Alma Bay, Magnetic Island, in 1976.
10. Phyllidia ocellata
One of the mainly gold-yellow Phyllidia species. Its typical pattern is four to ten black rings bordered in white, each with a gold or white bump in the centre, although individuals vary a lot. The Sea Slug Forum shows one photographed off North Stradbroke Island in southern Queensland, and museum specimens listed in the Atlas of Living Australia include animals from Lizard Island.
Bonus: polka dot nudibranch (Jorunna funebris)
Reef Life Survey gives its common name as the polka dot nudibranch and its maximum size as 7 cm. Its back is covered in tiny bumps. The Sea Slug Forum records two juveniles at Heron Island on the Great Barrier Reef, sitting on what appeared to be their food sponge.
Tips for finding them
Most of these slugs are small and slow, so go slowly and look closely at sponges, sea squirts and rock surfaces. Photograph the gills and rhinophores as well as the body, because several species share similar patterns. Our nudibranch guide has more spotting tips and advice on photographing them without disturbing them or the reef.
Wear your favourites
Our nudibranch collection brings these colours to neck gaiters, and there is plenty more sea life in our reef and ocean range. Visiting the island? Browse our Magnetic Island souvenirs and gifts. Everything is designed in Townsville, made to order, and ships free.