Melibe japonica from sthn Queensland

October 22, 2008
From: Kathy Townsend & John Kirkwood

Concerning message #21272:

Dear Bill,
We have since had additional sightings of the Melibe sp. The local prawn trawlers are picking them up in their nets. John Kirkwood from Griffith University has been recording them on observer trials and they have recently started picking up as much as 4 kg of the animals per net. John Healy and I are starting to feel even more strongly that it is probably Melibe japonica, if only for the colour alone. It is very red/pink. While M. viridis is thinner and green - unless they show a marked variation of colour we are unaware of.

While this is a really bad shot of the animals on the deck of a trawler, you can see the colour and the dropped off cerata within the mess. We would really appreciate your opinion. Particularly since there is some concern that they may have recently populated Moreton Bay, southern Queensland in large numbers and are becoming a pest species for the prawn trawlers.

Here is a comment from one observer: "we pulled up this species that were just a gelatinous mass (red spots/lines on them) - fisherman said they had only just started seeing them in Moreton Bay. We pulled up buckets of them, ranging from palm size to half kilo in weight".

Kathy and John

Townsend, K. & Kirkwood, J., 2008 (Oct 22) Melibe japonica from sthn Queensland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Kathy and John,

Although the photos are not perfect 'specimen shots' they certainly show the reddish pustules which seem to be characteristic of Melibe japonica, so I agree with your identification. Your suggestion that this may be a recent introduction to Queensland sent me back to earlier reports of Melibe from your part of the world, in particular Joyce Allan's description of Melibe mirifica from Cairns. As I discuss in a separate message [#21985] I am now of the opinion that M. mirifica and M. japonica are the same species. I guess I should have picked up on this earlier, but when I last looked at the original Melibe mirifica description I had not seen photos of living M. japonica and so did not know it had red pustules, as its original description was also rather lacking in detail.

What this means is that I am pretty sure this animal is not a recent introduction to Queensland, it has been there since at least 1931, and could be widespread throughout the western Pacific. I also think that the animals I previously identified as M. mirifica [#3026, #12461, #19393] are not that species.

I assume the swimming animal in the message from Colleen McGrath that you originally referred to [#21272] is also M. japonica, but although it is a good photo of swimming, and has a reddish tinge, it doesn't give any good clues which would allow me to confirm its identity.

Best wishes,
Bill Rudman

Rudman, W.B., 2008 (Oct 22). Comment on Melibe japonica from sthn Queensland by Kathy Townsend & John Kirkwood. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Melibe japonica

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