Madrella ferruginosa from Fremantle, Western Australia

February 20, 2007
From: Brent Murdoch


Hi Bill,
Can you please identify the attached. From the books I have I think it is a Madrella ferruginosa but the color is very dark. In its undisturbed state the "extra branchial appendages" are retracted, when disturbed they "fluff up" to
make it look twice the size. I have included a photo of this on my hand. Has
this been seen in the west before?

Locality: Fremantle, Swan River, 7.5, Western Australia, Indian, 05 February 2007, muddy. Length: 45 mm. Photographer: Brent Murdoch.

Brent Murdoch

brent@murdoch.id.au

Murdoch, B.D., 2007 (Feb 20) Madrella ferruginosa from Fremantle, Western Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19498

Dear Brent,

Yes this is M. ferruginosa. You will see on the Forum that there are photos showing animals as dark as yours. Most photos in books - and mine on the Fact Sheet - are brightly lit so we can see some detail. On the dark brown bryozoan the feed on they are almost invisible. The 'bristling' of the dorsal papillae that you describe is almost certainly a defensive behaviour. These animals don't have defensive cnidosacs, like the aeolids, but it is possible they have distasteful glandular secretions. They have a sac at the base of the papillae which can exude a yellowish secretion when they are disturbed. It seems to be based on waste fron the digestive system and so is most probably from their bryozoan food. Again, we don't know if it has a defensive purpose.

This species has been reported from southwestern Australia, but it has been misidentified as Madrella sanguinea, which is a smaller, bright red species, apparently endemic to southern Australia.

Best wishes,
Bill Rudman

Rudman, W.B., 2007 (Feb 20). Comment on Madrella ferruginosa from Fremantle, Western Australia by Brent Murdoch. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19498

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