The Killer Shrews are a group of gigantic carnivorous rodents that appeared in the 1959 classic "The Killer Shrews." In the film, they were used as lab rats, and when food sources ran out, they started killing humans in the process.
Their creation starts with a scientist's experiments in an isolated island. He tries to make human life-size, because for him smaller rats eats less which will reduce world hunger and for him to be famous. He uses shrews as lab rats because there are many in the island.
The shrews started killing humans when there were no more food sources the scientist can give them, and civilization is miles away. The shrews kill them all until three survivors were left and escape the island.
The shrews are dog-sized and have a bite-force strong enough to crush bones. During their hunting, they attack and gnaw their victim using their cone-shape canines. They also have poisonous saliva and hunt in packs and coordination.
Shrews in real life are just the same with the Killer Shrews (except for the size). They too excrete poisonous spits but shrews in real life are loners and avoid direct contact with other shrews. Their aggresiveness are legendary that it's said that they can scare away big dogs, household cats and swamp pythons. Their poison spit is also used in erasing and replacing botox.