Squid vs Cuttlefish: How to Tell Them Apart

If you see the animal up close, the eye is your first clue. Cuttlefish have that unusual W-shaped pupil that looks like a rectangular slot tilted sideways. Squid have round pupils like most animals. The second clue is the body: cuttlefish look like a bumpy pillow or small cloud, while squid look like a pointed missile or elongated balloon. Third is how they move. A squid shoots through water in straight lines with quick bursts. A cuttlefish hovers and wobbles, using its frilly fin to adjust position like a tiny alien craft. Watch the color too. Squid shifts color slowly over a minute or more. Cuttlefish flash colors and patterns in less than a second, sometimes creating a wave across their body. These three tells work together: shape plus movement plus color speed will tell you which one you are watching.

Squid range widely in size. Most species run 6 to 12 feet long, though the giant squid can reach 43 feet or more. Their bodies taper to a point at the rear, and their fins are narrow and positioned along the sides of their body. Cuttlefish are much smaller, typically 1 to 3 feet long, with a stouter, more rounded body. Their fins are thin and fringed, running along the entire edge of their body like the hem of a skirt. This difference in body shape is not accidental. Squid build streamlines for sprinting through open water where there is nowhere to hide. Cuttlefish build compactness to hover near rocks and reefs where instant camouflage is survival. Both carry ten arms, but squid use them for gripping and tearing prey while cuttlefish use them for exploring and probing crevices. Explore squid and cuttlefish pages for more details.

You will encounter these animals in different ways depending on where you live. Squid inhabit both the Atlantic and Pacific coasts of the United States. The Atlantic has longfin inshore squid and others that migrate into shallow bays. The Pacific has California squid and market squid that swarm in huge numbers. They prefer deeper, cooler water and open ocean settings. Cuttlefish are actually rare in US waters and mostly appear in the Atlantic near the Gulf Stream. European cuttlefish occasionally drift into Virginia and North Carolina. Most cuttlefish species live in warmer, shallower waters off Europe, Africa, and Asia. If you are in the US and see one of these animals, squid is far more likely. Divers on coral reefs around the world will see cuttlefish; US coastal swimmers almost always encounter squid if they see either one.

Squid and cuttlefish behave in ways that match their body design. Squid are active hunters. They dart toward prey, grab it with their long arms, and eat it quickly. They travel and hunt alone, though they sometimes gather in groups when food is abundant. Squid can see well but rely mostly on speed to catch fish and shrimp. Cuttlefish are patient hunters. They settle on the seafloor, match the pattern of nearby rocks or sand, and wait. When a small fish or crab walks by, the cuttlefish strikes in a burst, using its tentacles like a net. Cuttlefish are also more social and curious. They investigate objects, play with shells, and show distinct personalities in captivity. Both are smart and can learn, but cuttlefish show more complex problem-solving and social behavior. Squid are the speedsters, cuttlefish are the thinkers.

You are in the ocean or looking at underwater footage and see a cephalopod. Start with the body shape. If it looks like a streamlined rocket or torpedo, you saw squid. If it looks like a compact, bumpy, or cloud-like blob, you saw cuttlefish. Next, check the fins. Squid fins are on the sides and look like ears. Cuttlefish fins run along the edge like a skirt hem. If you still are not sure, watch how it moves. Squid zip and dart in straight lines. Cuttlefish wave and wobble, hovering in place. Finally, note the location and depth. If you are in the open ocean, deep water, or US coastal waters, it is almost certainly squid. If you are on a reef in the Mediterranean, Caribbean, or tropical waters, it is likely cuttlefish. In US waters specifically, squid are common, cuttlefish are unusual. Use these steps in order and you will have your answer.

The biggest mix-up is the name. Many people call cuttlefish 'cuttles' and think all cephalopods are squid. Cuttlefish and squid are different animals, though both are cephalopods alongside octopuses. Another myth is that squid have ink and cuttlefish do not. Both have ink sacs and both can release ink clouds to escape predators. Cuttlefish ink was historically used to make sepia paint, which led to the name cuttlefish coming from 'cuttle bone,' the chalky internal skeleton. Squid have a similar but thinner internal rod. Another false belief is that all squid are giant. Most squid are medium-sized and live in deep water. Only a handful of species reach giant size. Cuttlefish are not baby squid, and squid are not adult cuttlefish. They follow different evolutionary paths and have stayed separate species for millions of years. Both are equally ancient and successful predators in their own right.