Adding to the trend of “going nude” at the beach, is one of my favourite creatures, the Nudibranch.

As per those at the Whites Beach and the Pt Addis area, “Nudi’s” come in all shapes and sizes; with some being microscopic, far smaller than the tip of a finger nail and well camouflaged, and those being brightly coloured and up to around 2 cm’s (for those around here).

Derived from the Latin nudus (naked) and branchia (gills), as the name suggests, there is a naked component to these wonderful opisthobranchs.

They are members of the mollusc family, yet the adults are minus a shell and their gills are exposed. Without a shell to protect them they have very interesting means of protecting themselves from predation.

The chemical diversity in Nudi’s is extensive. Whilst the majority manufacture their own pigment others are fantastic recyclers. Having highly specialised diets, they re-use the colour pigments from their diet by incorporating them in their skin. Others capture and ably retain the active stinging cells of their food source, some “farm” elements to become “solar powered”, whilst others again alter defensive compounds to enhance them, for their personal defence mechanisms. Fancy being able to utilise the toxins from what one eats for one’s own protection. Super neat.

They are thought to live for only 1 x year, and with their species specific eating habits, they are sensitive to any disruption to their food source.

This weeks post shows the Nudi Rostanga calumus. Given the strong red colour of this Nudi it is likely it dines on red sponges. (Phone footage, Aireys Inlet, 2014.)

  • Rebecca Hosking @ FERMS