What is that thing

September 28, 2008 2:28 PM

What is this creature?

It's difficult to tell from the images, but this thing was about six inches long and moving across the surface of the water by bending and straightening its body. Picture taken yesterday at McKinney Falls State Park, Austin, TX.

posted by sanko to science & nature (9 comments total)

My guess is that someone dropped a hornworm in the water.
posted by pullayup at 2:31 PM on September 28, 2008

Polychaete worm?
posted by Lukenlogs at 3:25 PM on September 28, 2008

It could be this here, Pseudothyatira cymatophoroides. It definitely does not look like it belongs in the water, though.
posted by Gneisskate at 3:37 PM on September 28, 2008

Sea Cucumber, I would think. It has different coloration than the ones I've seen in person, but I am on the west coast of Canada.

Apparently quite a delicacy in some parts of the world.
posted by Kickstart70 at 3:57 PM on September 28, 2008

Hornworm caterpillar thrown in water was my first thought.
posted by kuujjuarapik at 4:05 PM on September 28, 2008

I agree that is is some kind of hornworm or similar large caterpillar that does not belong in the water. Here is the closest image in terms of pattern and coloration I could find, but it is just a flickr post with no identification. I can say with certainty, however, that it is NOT a sea cucumber as those are exclusively marine (not in the middle of Texas) and benthic (not floating on the surface of the water) and don't really look like that at all. It is similarly not a polychete worm, which would also be marine and also look nothing like that.
posted by DanielDManiel at 4:30 PM on September 28, 2008

Polycheate and Sea cucumber are dead wrong. Both are marine and this is freshwater.
posted by special-k at 4:52 PM on September 28, 2008

I did a quick search for caterpillars that live in the Austin area and came up with a silkmoth larva that looks pretty darn close: Eumorpha fasciatus.
posted by The Light Fantastic at 5:51 PM on September 28, 2008

A sea cucumber looks like a turd, sitting on the bottom. Or perhaps, like a used cucumber.

I wonder about the water, as I would expect this looks like lunch to a lot of fish. Where are those fish?

The photo from The Light Fantastic is great, as it shows the same markings along the side.
posted by Goofyy at 7:16 AM on September 29, 2008