Pleurobranchus hilli from eastern Australia

April 16, 2003
From: Sue Newson

Hi Bill,
I've been browsing your site for some time now and had to send you this information and photo's. I've been working on a live-a-board dive resort, Ocean Trek, situated in Jervis Bay, New South Wales, Australia. I've spent the past 4 years exploring the many dive sites (and still haven't done them all). I first came across this pleurobranch at a site on the southern side of the bay called Murrays Sandline. It has a depth range of 5 - 15m, beginning at 5m down a slope covered in seagrasses to 9m when the sand and muck dive begin. It was on the 16 December 2000 and I came across a mating pair. I cant tell you exactly the size, but the biggest was a lot bigger than 30cm. (the only thing I can compare it to is an oval plastic laundry basket. The other one was about 1/3 the size. I had no idea what it was until I recently saw it again, then began to see it in various locations around Jervis Bay. The first resighting was on 11.02.02 at around midday. It was buried under the sand with its tubercules exposed. I uncovered it and tried to lift it at the edge and the tiny piece I was holding broke off. I saw it regularly until the 30 December 2002.
Best wishes,
Sue Newson

Dear Sue,
Welcome to the Forum and thanks for the contribution. This is Pleurobranchus hilli, another species of Pleurobranchus absent from the Forum before your message. Being a subtidal, sand-dwelling species it is not often encountered, and so we don't have many records of it. I suspect however that it is nowhere near as rare as out list of sightings would suggest. As you have discovered, this would appear to be one of the giants of th pleurobranch world. For those of you unfamiliar with the species, the white reticulate pattern in the above photos is formed from white sand sitting on, or adhering to, the mantle. If you run across the species quite often, it would be nice to have some idea of what it eats and what its egg ribbons look like.

We may already have an idea about its egg ribbon as I have found an earlier message from Grey McNeil from Port Stephens, which shows an animal which is most probably is this species, laying eggs. It has been languishing, rather lost, amongst the P. forskalii messages.
Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Apr 16). Comment on Pleurobranchus hilli from eastern Australia by Sue Newson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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