The only animal (mammal) that lives exclusively on blood is the Vampire Bat.
The biological word for this diet tract is Hematophagy.
The species of bat are fed on blood are: the common Vampire Bat, the hairy-legged Vampire Bat and the white-winged Vampire Bat.
They can be found in Central and South America.
The Vampire Bat has a sensor on his nose called thermoreceptor that help it finding the spot where the blood is flowing in the animal skin.
Vampire Bats are very agile and they can run very fast on land as well as fly.
They only hunt when it's dark. Common Vampire Bats are fed exclusively by mammal's blood (this include human's blood) and hairy-legged and white-winged are fed on bird's blood.