These things hit a lot more than their level would suggest, and they are social. A level 26 warrior and 31 bard wound up killing one and giving the other up as a bad job, since the first didn't drop anything at all. Not like we needed to swim near them!
I add my confirmation to this info as of 4-30-05. The one that attacked me in the moor near Paludal was hitting for consistent 38's, followed by a friend that was hitting for 42's. Careful with these little fellas.