Invasive SpeciesCompound sea squirt

Didemnum vexillum
FOUND by SacoHarry
Ocean Park, ME
ID Confirmed
Quality checked by AMD
Peer reviewed by SMO
Field Notes
Walked the beach to pick up debris following large storm. Noticed that usual high-tide line was littered with hundreds of clams that had been deposited there live (see photo of site location taken two days later, 3/19), and manmade debris. Benches usually well-clear of high-tide line had been buried by over a foot of sand from the storm. Noticed what seemed to be corals nestled at edge of dune grass close to benches. Somehow they seemed "wrong," so I collected the ones I found. Returned on 3/20 to collect a few more. 8 pieces total, 5 from edge of dune grass, 3 caught up in kelp at "normal" high-tide line some 50 feet east of dune grass.
Supporting Evidence
Photo of my evidence.
All told, I found eight pieces, 5 on 3/17, 3 more on 3/20, all within about 50 to 100 feet of each other. 5 had blown up as far as the edge of dune grass, 3 were caught amongst kelp and debris at the usual high-tide line. The largest piece is is about 3 inches long by two inches wide by two inches thick. The smallest is about one inch square and a quarter-inch thick. Each of these pieces is exceptionally lightweight, very spongy to the touch, but with a smooth surface. Each piece is covered with hundreds of pore-like pockmarks, some deep enough for aquatic plant life to have taken hold; in others very small shelled sea creatures seem to have made their home. All 8 pieces a fairly uniform dull creamy white color. They have a faint scent, which I find unpleasant. Not rotten, exactly, more acrid, perhaps one could call it slightly smoky.
Photo of my evidence.
This is a close-up of one of the larger pieces, approximately 2" X 2", and maybe 3/4" thick. It shows the aquatic plant life that seemed to be growing out of the pores.
Photo of my evidence.
This is the largest of the 8 pieces I found, about 3" X 2" by an inch thick. The picture shows what appears to be a tiny (~3 mm) shelled creature that had taken up roost in one of the larger pores.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Didemnum vexillum
Common name:
Compound sea squirt
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 43.499756 °
W -70.383182 °
Observation Site Information
A photo of our study site.
Coastal - Beach or dune
Trip Information
Ocean Park Beach
Trip date: 
Wed, 2010-03-17 13:05
Town or city: 
Ocean Park, ME
Type of investigation: 
Species Survey
Time of low tide: 
Wed, 2010-03-17 06:46


The careful detail of your observations and the visual impact of your species photos are inspiring and exemplary.

I'm interested in why you chose the striking red background for your photos. It certainly got my attention.

Looking forward to your next observation.

Thanks to both of you for such nice comments. I'm excited to keep my eyes peeled next time I walk the beach; now I know you just never can predict what the tide will bring in.

I stumbled into the background through good dumb luck. My first pics were taken against our light-colored carpet, and just washed the specimens out. I noticed a bright red coffeetable book next to me in a stack and figured I'd give it a try!

Your intimate understanding of your place and ability to notice when something just doesn't seem right is refreshing. ...and who needs the real deal to hold and contemplate with furrowed brow when they have your stellar photos and detailed observations at the ready online?! Simply great evidence.

Keep posting the stuff you find that "seems wrong!"