City - Sol Duc River State - WASHINGTON Country - United States
About
I spotted this animal in Sol Duc River, a fast-flowing river in the northwest of the Olympic Peninsula, Washington state, USA. There were hundreds of them, all located on rocks as shown in the picture, about 4 to 8 inches (10 to 20 cm) beneath the surface of the water. The animal is a little over half an inch (about 15 mm) long. It is clearly an arthropod, probably an insect (if those 6 legs are all it has). It seems to me that the legs are all we're seeing here of the actual animal, its "harness" looks like a contraption of tiny stones and seeds, glued together with a secretion from the animal's body. I gently touched the creature with a twig, and it did not flee or otherwise appear agitated. It did move a bit, making sure it held on to the rock. Clearly being on these rocks is important for the animal; I figure it can breathe under water, and that it feeds by grazing algae and/or other microorganisms off these rocks. Can anybody tell me more about this creature? Post-editing done on this picture: downsized from 2560 x 1920, clarified and sharpened.
Thank you very much, Tony! I took a look around on the internet, and the information I found confirms this is indeed a caddisfly. I'd like to do something nice for you -- maybe I could (try to) make a picture according to your instructions, and then send it to you or post it here?
It turns out this animal is related to moths and butterflies. It spends most of its life as a larva under water, in a protective case of sand and other materials, spun together with silk. Only the last few weeks of the animal's life is spent as a moth-like creature, with hairs instead of scales on its wings, and focused entirely on procreation. Since I found these animals ON rocks and not under them, I figure they were fairly "mature", i.e. close to pupation and adopting the moth-like form. For those who are interested, there's a webpage with brief, to-the-point information and good pictures at http://www.cirrusimage.com/Trichoptera_caddisfly.htm A bit more in-depth information can be found at http://tolweb.org/tree?group=Trichoptera&contgroup=Endopterygota and at http://en.wikipedia.org/wiki/Caddis_fly
0 
{K:23858} 8/16/2007
