Unusual Sea Slug

01/08/2019

Emma asks: "My dad and I found this peculiar slug at Warrington Beach in a rockpool and we don't know what it is. it was 6 cm long when stretched out. 

I would be very grateful if you could tell us what it is.

Scientist response:

This is one of the more beautiful nudibranchs found locally. It is described as relatively uncommon but we have found one on the shore at Portobello, and it seems to be regularly seen at Blackhead.

Its name has recently been changed to Aeolidiella drusilla. They are light sensitive so that might explain why they are not seen oftem.

It has feathery projections (cerata) on its back, which are extensions of the gut. It feeds on hydroids and like sea anemones and jellyfish, they have tiny stinging cells. This slug eats the hydroid without discharging the stinging cells and then stores them in their cerata for its own use to ward off predators.

This slug has a NZ wide distribution and apparently extends from the low tide zone to 12m. We are interested to hear where else people find it in the intertidal zone.