6. Bats are the slowest reproducing mammals on earth.
Moms give birth to only a single pup each year, making bats very vulnerable to extinction. Fortunately for their survival, the've been known to work together. Contrary to what the name might imply, Vampire bats can be particularly sweet: They adopt orphans—one of the few mammals willing to risk their lives to share food with less fortunate roost-mates.
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