- Common Name:
- Squid
- Scientific Name:
- Teuthida
- Diet:
- Carnivore
- Average Life Span In The Wild:
- 1 years
- Size:
- 0.8 inches to 16 feet long on average
What are squid?
Squid have been around for millions of years, and inspired legends of terrifying ship-devouring sea monsters. But far from brutes that terrorize humans, these masters of deception rely on their wiles to survive, and their ingenious behaviors have pushed forward futuristic innovations like intelligent camouflage and self-healing robots.
The more than 300 species of squid are found in every ocean, where they can live alone or in schools. While some squid live in shallow waters, the deepest recording of a bigfin squid was a staggering three miles below the surface.
Squid also come in all sizes: from pygmy squid that are the size of a pinky fingernail to giant squid which may reach as many as 59 feet long—which is perhaps why this gigantic beast inspired the legend of the Kraken. However, while the oldest known example of a squid-like creature attacking prey dates back nearly 200 million years, squid are not known to hunt humans, or sink ships.
Appearance
Like octopus and cuttlefish, squid are a type of cephalopod, Greek for “head foot.” Behind the animal’s head is a soft, elongated mantle: a muscular space containing its organs. Unlike an octopus, which has no skeleton, squid have an internal shell called a gladius, or pen. This stiff backbone-like structure supports the mantle and gives muscles something to attach to so the squid can keep its shape.
A squid’s mouth—found at the base of the mantle—has a hard parrot-like beak for killing and eating prey, which include fish, crustaceans, and other squid. Surrounding the mouth are two long tentacles with suckers at the tips that the animal uses to grab prey and eight sucker-lined arms that it uses to hold its meal while it eats.
Reproduction and behavior
Squid have short life spans and usually die soon after mating, at around one year old. After copulation males stay close to the female until she lays her eggs to prevent others mating with her, a behavior called mate guarding. Paternal care among cephalopods is rare so scientists were surprised to find that male bigfin reef squid help choose homes for their mates.
Squid move by jet propulsion. They fill their mantle with water through small openings in their head, then eject the water through a funnel called the siphon, which moves to adjust direction. Some species can build up enough speed to become airborne. They launch themselves into the air, fan out their tentacles like a sail, and fly above the surface for up to 164 feet. This may be to save energy or escape from predators. While they are not technically able to fly, this behavior has earned some species the name “flying squid.”
Intelligence
Squid are highly intelligent: They can rapidly change skin color using special pigment-filled cells called chromatophores to hide from danger, warn off potential attackers, or use the patterns on their skin as a secret code that allows them to communicate with other squid while remaining invisible to predators. And that’s not all. Squid can also make themselves transparent, override their genetic code, and some species, such as the Humboldt squid, work together to hunt in packs.
One squid species even evades predators by breaking off its own arms. Just like a lizard might detach its tail, the Octopoteuthis deletron tears off the wriggling tips of its arms and leaves them behind to distract the predator while escaping. Although some octopus species do this, it has not been observed in any other squid species.
This is not the only way squid use deception for survival. They also squirt ink clouds as a distraction or decoy to escape predators. Japanese pygmy squid (Idiosepius paradoxus) release ink as a smokescreen when hunting, allowing them to attack unseen; or as a diversion so they can sneak up from behind. Scientists have also discovered a deep-sea squid, Grimalditeuthis bonplandi, which uses its long, tentacle-free suckers like a fishing lure—mimicking tiny marine organisms to attract prey.
Inspiring innovation
Despite being difficult to keep in captivity—and therefore harder to study than octopus—these crafty animals have inspired many innovations. Their color-changing abilities have helped researchers develop smart materials that can blend into the surroundings. The tiny yet strong tooth-like denticles on a squid’s sucker—which help grasp onto slippery, struggling prey—inspired the creation of synthetic proteins that are used to make durable, eco-friendly packaging and self-healing machinery that can repair themselves in seconds when damaged. And, for many years, scientists have used squids’ nerve fibers to study how the human brain works because they are larger and easier to dissect.
Threats to survival
While most species are not listed as endangered, squid are still threatened by overfishing. Despite their reputation as legendary sea monsters, squid are prey to many animals, including fish, sharks, seals, sperm whales, and humans—if you’ve eaten calamari, you’ve eaten squid. Scientists believe squids’ inability to detect high frequency noises, like a dolphin’s clicks, could explain why they fall prey to so many animals.
Rising temperatures caused by climate change have caused populations to boom in the Pacific Northwest and Alaska. Because of the complexity of ecosystems and food webs, scientists aren’t yet sure what wider impact this could have on the environment. So, it’s still important that squid stocks are managed appropriately to ensure the animal’s long-term survival.
Did you know?
Like other cephalopods, squid have three hearts: two to push blood through the gills and one to pump blood around the body.
—Smithsonian
The giant squid’s eye is around the size of a volleyball—larger than any other eye in the animal kingdom.
—Australian Antarctic Program
The United Kingdom recognizes squid as sentient beings that feel pain, distress, pleasure, boredom, and excitement—meaning their welfare are considered in policymaking.
— U.K. Department for Environment, Food & Rural Affairs
