Blood is nutritious, easy to digest, and not hard to come by, so it’s unsurprising – if a bit unsettling – that thousands of species have evolved a taste for the stuff. From birds to bats to bugs, the diversity of sanguivores includes a wide variety of body plans, feeding strategies, and unique evolutionary histories, all converging upon a similar set of behaviors and features honed for a diet of blood. Be aware, this episode is, at times, kinda gross.