Cerberilla asamusiensis from sthrn Queensland

September 4, 2009
From: Gary Cobb

Concerning message #7457:

Hi Bill and everyone!
Great to see you're back in the Nudibranch Saddle! I wish to present to the Forum a species I find pretty incredible.
While sieving the white sand off the shore of Bulwer Beach, Moreton Island in about 4 m of water, I "uncovered" Cerberilla asamusiensis!

Locality: Bulwer Beach, Moreton Island, 4 m, Queensland Australia, Pacific Ocean, 12 July 2009, Subtidal. Length: 23 mm. Photographer: Gary Cobb and David Mullins

Got the animal onto the boat where it started immediately laying eegs. I have included a closeup photo of the eggs and they appear to be dividing after only 2 hours. Can this be? Is it possible the egg is born in multiple yokes?
I have also included a closeup of the cerata. The digestive organ is clearly visible.

This species has the widest foot I have seen.
Cheers
Gary

gary@nudibranch.com.au

Cobb, G.C., 2009 (Sep 4) Cerberilla asamusiensis from sthrn Queensland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22605

Dear Gary,

This is an interesting find. It certainly looks like C. asamusiensis, which would make this a huge range extension from Japan. The egg ribbon is also very interesting as we have little information on the biology of any species of these sand-dwelling aeolids. Looking at the eggs, some seem seem to have divided past the 4 cell stage so I am pretty sure this is egg division rather than cluster of 4 discrete eggs in each capsule. Not all nudibranchs lay their eggs at the single cell stage. I have observed some species of Pupa, such as Pupa kirki, delaying laying until the eggs were just about to 'hatch' as free -swiming veliger larvae. I guess if you are a sand-dweller and it is difficult to find 'safe' permanent structures to stick your egg ribbon to, there is an advantage in keeping the eggs until they are a late embryo. In this way they are less likely to be washed away from their preferred habitat.

Best wishes,
Bill Rudman

Rudman, W.B., 2009 (Sep 4). Comment on Cerberilla asamusiensis from sthrn Queensland by Gary Cobb. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/22605

Factsheet

Cerberilla asamusiensis

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