The bats incisor teeth are hollow, allowing them to suck blood in through the teeth like a straw, the saliva has several ingredients that prolong bleeding.
My favorite thing about this is: where does the blood go once it hits the top of the tooth? Into the gums? Into the sinuses? Out the back of the tooth and into the mouth, removing the need of a straw in the first place?
Circa 2008 the wikipedia entry for vampire bat claimed that their teeth were like this. archive.org didn’t capture it at that time, but another page copied the whole thing: https://www.mundoandino.com/Argentina/Vampire-bat
My favorite thing about this is: where does the blood go once it hits the top of the tooth? Into the gums? Into the sinuses? Out the back of the tooth and into the mouth, removing the need of a straw in the first place?
I assumed they were basically reverse snake fangs
Diagram
One is the venom tooth and one is the straw tooth.