Squid are an important food source for many different fish, including most of the large predatory species. Marlins, tuna and groupers frequently eat squid, and sharks and rays consume the mollusks as well. In addition to fish, dolphins, whales, sea mammals and oceanic birds predate on squid.
Most sharks, including thresher sharks, bull sharks and hammerhead sharks, consume squid when the opportunity arises. However, some species, such as blue sharks, are especially fond of them. According to the BBC, giant squid were thought to have only one predator ? sperm whales. However, a new study has found that sleeper sharks are also important predators of the large mollusks. It is possible that the sharks only scavenge dead or dying squid, as it appears the sharks frequently eat squid larger than themselves.
Squids have a variety of defensive mechanisms for dissuading predators. Their camouflage coloration, speed and agility are helpful for avoiding prey, but they can also spray dark ink into the water when attacked. This ink helps the squid to distract their predator long enough to escape. Some squid species are capable of disconnecting an arm if it is grasped by a predator.
Large squid are also an important predator of other squid, and they even eat other members of their own species.