Some claim a shrew is size which.
The taming of the shrew is no small matter. It is the world's smallest mammal but a most ferocious, ill-tempered and bloodthirsty creature. Its body is only 2 to 4 inches long, tail included, but it will eat animals several times its size. ... That is equivalent to an adult human eating 100 to 200 pounds of food
Get bite by one and your hand goes paralyzed for hours, trust me.
and it's not pound per pound but micro-gram per kilo gram force.
Cool pic Bruce T