While most vampires prefer their prey alive, vampire squid are rather less demanding. They munch on any dead plankton, crustacean remains and faecal matter that happens to pass by, making them the only cephalopod not to hunt living prey.
Vampyroteuthis infernalis – literally the "vampire squid from hell" – has a pair of thin, retractable filaments. It uses them like a fishing line, letting them drift and collect bits of waste. Wiping the filaments across its arms, the squid combines the waste with mucus secreted from its suckers to form balls of food, which it gobbles up.
This diet, unique among cephalopods, allows the squid to live in environments that are too difficult for most predators to survive in, says Henk-Jan Hoving at the Monterey Bay Aquarium Research Institute in California. He studied the squid's eating habits using a 20-year-long record of observations captured by deep-diving remotely operated vehicles in Monterey Bay.
Other squid and octopuses use their suckers and strong arms to capture prey, but the vampire squid's passive approach to finding food means it does not have to spend energy building muscles and chasing down live animals. This allows it to live in low-oxygen zones, where water doesn't circulate much and most predators cannot venture for long.