stunning little sea slug Nudibranch

Hear all about it!

Nudibranchs move in the same way as land snails and slugs by sliding along on a muscular foot. They are carnivores and feed on animals that are sedentary (stay in one place). Nudibranchs have two highly sensitive tentacles called rhinophores on top of their head which they use to identify prey.

Nudibranchs protect themselves from predators with skin glands that contain chemicals that are either poisonous or distasteful to fish. It is thought the bright colour of the nudibranchs helps the fish to “remember” through association, just how unpalatable they are. Nudibranchs can also use the poisonous chemicals found in their prey for their own body defence.

Nudibranchs are hermaphrodites. This means the animal has both female and male reproductive organs. Mating pairs transfer sperm into each other. The fertilised eggs are then deposited in a coiled mass on a surface in the marine environment. The eggs hatch into larvae, which swim about in the water column until they are ready to settle on the sea bottom. Nudibranchs have a lifespan of usually less than a year and often as little as a month.

Threats include; human disturbance (standing on reef and coral, collecting), pollution and aquarium trade

Where you can find a Nudibranch

Conservation Status

The waters around Rottnest Island are a designated Marine Reserve. Also, some parts of Rottnest’ coral reefs are included the Marine Sanctuary Zones shown in the Rottnest Island Marine Management Strategy (2007).

  • Extinct
  • Extinct in Wild
  • Critically Endangered
  • Endangered
  • Vulnerable
  • Near Threatened
  • Least Concerned

Help keep Rottnest’s beaches and reefs healthy

  • Do Not stand on reef and coral while snorkelling or diving
  • Do Not remove or collect Nudibranchs
  • Do anchor only in sandy areas of water
  • Do take litter with you or use bins provided
  • Do collect fishing line if seen in ocean or on shores