Meet North America's only venomous mammal, the Northern Short-tailed Shrew!

The Northern Short-tailed Shrew is a tiny but fierce predator, subduing its prey with neurotoxic saliva.

Don't worry, unless you are a small mammal, invertebrate, or a small amphibian, the short-tailed shrew's venomous saliva is not medically significant to humans.

Despite their tiny size, these little hunters have a huge appetite and need to eat up to half their body weight in food a day to keep up with their metabolism.

Not exactly the kind of animal you'd expect to be venomous!

To save you a wikipedia search:

The saliva of the northern short-tailed shrew contains a kallikrein-like protease, used to paralyze and subdue its prey. The toxin is strong enough to kill small animals, up to sizes somewhat larger than the shrew itself, and results in painful bites to humans who attempt to handle the shrew. The venomous saliva is secreted from submaxillary glands, through a duct which opens at the base of the lower incisors, where the saliva flows along the groove formed by the two incisors, and into the prey. The toxin is very similar in structure to the one produced by the Mexican beaded lizard (Heloderma horridum) which independently developed its toxin from the same precursor protein.

For you true shrew-ophiles, a relatively fun article on soricidin and blarina toxin, 2 poisons found so far in the shrew venom, a little on how they work, the people that discovered the compounds, and potential pharmaceutical benefits. With a read!