Tularia bractea from eastern Australia

Dear Leanne & David,

This is an interesting find and I am pretty sure it is a colour form of Tularia bractea, although as usual - we would need to check its anatomy. That species has been previously reported from so far up the east coast of Australia but, previously been known from the Bass Strait region and New Zealand.

It is clearly not a species of Phidiana, or related genera, which have the cerata arranged in rows, but the rows are arranged in regular groups or clusters of up to 6 rows. The smooth rhinophores and long tentacular anterior foot corners are characters of Tularia, but probably the most characteristic feature are the ridges (or 'bracts') on which the cerata are inserted. very few aeolids have such pronounced structures.

Concerning them being on the bryozoan Amathia tortuosa. In your photo with the eggs, all I can see are hydroids.  I have looked carefully at the full size files of your other two photos but can't see any sign of Amathia. All I can suggest is that the ones you saw on  Amathia were there because the bryozoan had settled and grown on hydroid colonies which had been eaten out by the aeolid. Often when you see great numbers of egg ribbons on a hydroid colony you can be sure when you look closely that most of the hydroid polyps have been destroyed. I am afraid the life cycle of aeolids is quite short and brutal. They settle on a colony of hydroids and quickly eat all the polyps. If the colony is large enough the aeolid population will be able to mate and lay their eggs before the adult either die from old age or starvation.

Best wishes,
Bill Rudman