You think Dracula is bad? At least he's a fictional bloodsucker. You don't have to worry about him leaping on you in the middle of the night to siphon the blood from your skin, or wiggling his way up into your urethra to feast on your insides when you decide you want to go for a swim. These real animals that drink blood are notorious for actions like these, though. The vampire animals that live out in the wild (and even in people's homes) pose more of a threat than any famous movie fiend ever could.
Hematophagy, or the act of eating blood, is a common practice in the animal kingdom. After all, blood has tons of tasty proteins and lipids, and it's extremely easy to come across. Bloodsucking animals are all around, sinking their teeth, snouts, and other appendages into whatever tasty blood-host proves to be the most appetizing.
The vampire ground finch earned its name from its blood-siphoning habits. While it may look like a normal bird, its neighboring avians are in on its vampiric secrets. Sharing its habitat with boobies and other seabirds, the vampire ground finch will peck away at their skin with its sharp beak so it can break the surface and drink their blood.
Oddly, these other birds don't fight the finch's snacking. Experts theorize that the finches used to eat unwanted ticks and flies off the seabirds' backs, and the larger birds simply got used to the unusual relationship.
Candiru are very small, parasitic catfish that feed on the blood of other fish. Averaging less than an inch in length, these tiny bloodsuckers have been observed swimming into the gills of other fish to anchor themselves to their insides and feast. The fish do this to mammals as well, notably swimming up the urine streams of humans to latch onto the urethra.
There are three types of vampire bats who live off of blood alone: the common vampire bat, the hairy-legged vampire bat, and the white-winged vampire bat. All species hunt exclusively in the dark, seeking out their food sources through echolocation. Although sleeping livestock are a common meal for vampire bats, they occasionally nip at humans, too.