Animal Kingdom Animalia (Animals)

This is a pretty clear photo of an Epeorus nymph clinging flat against a log. The big mound of debris on the bottom center of the picture, attached to the light rock, is a structure that's been puzzling me. I've found several in one section of the river. It's big, like 2 inches long and maybe 1/2-3/4 inch wide/tall, and hollow, like some sort of coccoon or something. It's clearly a structure built by some sort of little creature, but I'm not sure what.

In this picture: Mayfly Genus Epeorus (Little Maryatts).

I spotted this very large leech freely tumbling, and occasionally stopping, along the bottom of a clear, cool trout stream. I paid careful attention later and spotted two more like it, but this one was the largest -- probably over 7 inches stretched out.

There is one other picture of it.

In this picture: Animal Class Clitellata-Hirudinae (Leeches).

This tiny sculpin is the size of a mid-sized mayfly nymph.

In this picture: Fish Order Cottidae (Sculpins).

A water boatman and a scud are visible in this picture. Can you find them?

In this picture: True Bug Family Corixidae (Water Boatmen) and Arthropod Order Amphipoda (Scuds).