April 1, 2008
From: Ryan Murphy
I've frequently noticed pieces of Ulva covered with uniform shapes like this one here.
I decided to take a quick picture to see what they were. The shape of the head and body reminded me a lot of the Elysia chlorotica I was working with in New Brunswick. I see that Newfoundland is way beyond the range of E. serca, and even past the range of E. catulus (if they are indeed separate species). Are there other candidates I'm not thinking of?
Locality: Tapper's Cove, approx. 15 m, Newfoundland, Canada, Atlantic Ocean, Torbay, 20 October 2007, gravel bottom. Length: approx. 5 mm. Photographer: Ryan Murphy.
email@example.comMurphy, R.M.J., 2008 (Apr 1) Elysia serca in Newfoundland?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20996
It is a bit hard to make out much detail in your photo, but if you are familiar with the shape of Elysia chlorotica then I guess we are not looking at a flatworm infestation. Elysia catulus is the most likely identification, and just because it has not been reported north of Nova Scotia certainly does not rule out the likelihood of it being found in Newfoundland.
As far as I can find, E. catulus has only been reported to feed on the sea-grass Zostera, which makes it almost unique amongst the sacoglossans. As is discussed elsewhere on the Forum, E. serca is an extremely similar species from further south on the west Atlantic coast and is probably the same species. Interestingly it is reported to feed on a variety of sea-grasses and also Ulva, which your animals are also apparently feeding on. It would be interesting to know if this snimal also occurs on Zostera in Newfoundland. Perhaps it changes food seasonally?