This tiny water shrew, the size of a thumb, is the world’s smallest warm-blooded diving species. It lives in the cool forests and montane regions of Canada and the USA. With a high metabolism ...

It weighs 10-17 g (0.35-0.60 oz), slightly less than the largest short-tailed shrew. The water shrew’s weight and long tail (67-71 mm, 2.6-2.8 in) (as long or longer than the combined head-body length ...