I take Zoology at uni (hence the interest and posting in this thread!) and I was on a field trip a few weeks ago doing some small mammal trapping. Held a couple of common shrews (unfortunately not a water or pygmy shrew) among other things. Was a bloody fast bastard though! Tried to bite through the bag we put him in For your first point, I maintain that no mammal would win this contest. They act too much when threatened, and don't just go out to attack things for no reason - a trait seen too often in the insect world.