Killer Shrew

The Killer Shrew appeared in 1959 movie called The Killer Shrews and 2012 movie called Return of the Killer Shrews. Its an unnamed species of vicious, venomous, dog-sized "Killer Shrews" were accidentally created by Dr. Marlowe Cragis and his team working on an unnamed island off the coast of Texas. The creatures weight between 50 and 100 pounds, and have enormous fangs which deliver deadly poisonous saliva. This makes them extremely dangerous, as even a small scratch from them is enough to result in near-instantaneous death for the victim. Unlike normal shrews, they are pack hunters, and afraid to go into water. Cragis and his associates hoped to find a way to combat global overpopulation by altering human metabolism so as to make people require less food. They attempted to alter their test subjects - small shrews - in order to increase their body mass to slow down the metabolism. Unfortunately, the research was vastly unsuccessful, as the creatures grew several times larger and started mutating, while retaining the natural voraciousness for which the species is famous.

They have since established a population of about two or three hundred individuals. Fortunately for the rest of the world, their inability to swim means they're still confined to the island, which doesn't have a sufficiently productive ecosystem to sustain their numbers for long - meaning that in the near future the Killer Shrews will most likely go extinct, unless they rapidly adapt.