The vampire squid is a small ( 12-inch-long ) cephalopod found in deep temperate and tropical seas. Originally thought to be an octopus because it lacks the two long tentacles that usually extend past a squid’s eight arms, the vampire squid possesses characteristics of both squid and octopi, and occupies its own order in taxonomy (scientific classification).
On the freshwater side, the vampire fish is a nickname for the payara, an abundant gamefish found in the Amazon Basin. While this large, 1.5-to-3 feet, fish does not suck the blood of its prey, its six-inch-long fangs, which protrude from an undershot jaw, result in a face only a (payara) mother could love.
Original article: What are the vampire squid and the vampire fish?