Perhaps we should have saved this column for Chinese New Year since the Blue Dragon nudibranch, (Pterolidia ianthina), really looks like it should be part of the parade.

Nudibranchs are small molluscs that do not have a shell. The Blue Dragon was first discovered in Sydney Harbour 120 years ago but is one of the most common and largest nudibranchs seen on Eurobodalla’s shores, reaching a length of 150mm. It lives on reef from low tide to 30 metres deep and can also be found in many parts of the tropical and subtropical Indian and West Pacific Oceans.

The colour of Blue Dragons varies considerably due to the animal’s ability to capture and farm microscopic algae (zooxanthellae) just like corals do. The more zooxanthellae the nudibranch has the browner it looks.

The projections on the nudibranch’s back function as gills and also contain branches of its stomach. When the animal feeds on soft corals it does not digest their zooxanthellae but instead diverts them to the projections on its back. Here the algae flourish and reproduce in their protected “greenhouse” and use the sun’s energy to make sugar, a high proportion of which is passed on to the nudibranch.

The Blue Dragon’s favourite food is a large solitary hydroid, an animal that is somewhat like a very simple sea anemone on a stalk. The hydroid is often found embedded in greyish soft coral colonies. However, due to the nourishment it receives from the zooxanthellae, the nudibranch can often go a long time without feeding.

The spectacular striped “horns” on the Blue Dragon’s head touch and taste its surroundings. The feathery pair of tentacles behind are especially good at “smelling” the water.

Like all nudibranchs, Blue Dragons are hermaphrodites - both male and female simultaneously. They reproduce by exchanging sperm packets then produce eggs. However, unlike other nudibranchs, the adult stays with its mass of eggs and protects them.