What Is Octopus Eat?

An octopus eats crabs, clams, mussels, snails, shrimp, and small fish. It hunts mostly at night, grabs prey with its arms, and uses a sharp beak to crack shells open. Some species also eat other octopuses. What an octopus eats depends on where it lives and how big it is.

There are more than 300 known species of octopus, from tiny ones the size of a golf ball to the giant Pacific octopus, which can span several feet across. Each species eats what its body can handle and what its habitat provides. That range is wider than most people expect.

What Is Octopus Eat in the Wild?

Wild octopuses are predators, and most of them are built to eat hard-shelled animals. Crabs, clams, mussels, oysters, and snails make up a large part of the diet for many species. Shrimp, lobsters, and small fish round it out.

The octopus has a beak in the middle of its arm crown that looks like a parrot’s beak. It can crack through the shell of a crab or pry open a clam. Once the shell is open, the octopus uses a structure called the radula — a tongue-like ribbon covered in tiny teeth — to scrape out the meat.

Different species lean toward different prey. The common octopus, found in warm and temperate waters around the world, eats mostly crustaceans and mollusks. The giant Pacific octopus, which lives in colder northern waters, takes larger crabs and clams and has been documented eating fish as well. Small tropical species often feed on shrimp and tiny crustaceans.

One thing that surprises people: octopuses are cannibals. Larger octopuses will eat smaller ones, including members of their own species. This is well documented in the wild and in captivity. It is one reason octopuses are difficult to keep together in tanks.

How Does an Octopus Hunt Its Food?

Most octopuses hunt at night. They leave a den — often a crevice in rock or a hole in the seafloor — and search the bottom for prey. Some species use a different approach: they drift or crawl along and pounce when they find something.

Octopuses have excellent eyesight, and their skin contains cells called chromatophores that let them change color and texture quickly. This helps them blend into the background while stalking prey.

Once they find a target, the arms do the work. Each arm has suckers lined with chemical receptors. In effect, the octopus can “taste” what it touches. Some research indicates the arms can make decisions somewhat independently of the brain, which helps an octopus probe a crevice while watching for predators.

For hard-shelled prey, the octopus has a few strategies:

• It wraps its arms around the shell and pulls it apart with force.
• It drills a small hole through the shell and injects digestive enzymes or venom, depending on the species.
• It uses its beak to crack the shell directly.

Some octopuses carry rocks or shells to use as tools, and at least one species has been observed carrying coconut shell halves to hide inside. Tool use is unusual among invertebrates, and octopuses are one of the few animals outside birds and mammals documented doing it.

Do Octopuses Eat Fish and Other Octopuses?

Yes to both. Many octopuses eat small fish when they can catch them. Some species hunt cooperatively with groupers or other fish, though the details of this behavior vary by species and location. A hunting octopus that flushes prey out of a crevice sometimes lets a waiting fish grab what escapes — a loose partnership rather than a true team.

Cannibalism is common. Larger octopuses eat smaller ones, and this happens across many species. In some cases, a female octopus near the end of her life may be eaten by her own offspring, though this is not universal and varies by species.

The extent of fish-eating in the octopus diet is often overstated in popular writing. For most species, crustaceans and mollusks are the staple. Fish are opportunistic meals, not the main course.

What Do Octopuses Eat in Captivity?

Captive octopuses eat a diet built around what their species eats in the wild. Common foods include live or thawed crabs, shrimp, clams, mussels, and squid. Some aquariums feed fish, but this is usually a supplement rather than the base of the diet.

Live prey is often preferred because it gives the octopus something to hunt, which is natural behavior. But live crabs and shrimp can injure an octopus, so many facilities use frozen and thawed seafood instead. Feeding schedules vary. Some octopuses are fed daily; others eat less often depending on size and species.

No published clinical feeding guidelines exist for octopuses the way they do for dogs or cats. Aquarium husbandry is based on observation and species-specific practice rather than controlled feeding trials. That is worth knowing if you are setting up a home tank. Octopuses are difficult to keep, and most species are not suited to home aquariums.

What Do Baby Octopuses Eat?

Baby octopuses eat tiny prey. Newly hatched octopuses, called paralarvae, are often only a few millimeters long. They feed on small crustaceans, larval shrimp, and other microscopic animals in the water column.

This stage is one of the hardest parts of the octopus life cycle to study and to replicate in captivity. Many species have paralarvae that are so small and so specific in their food needs that they have never been raised to adulthood in a lab. This is a major reason octopus farming has been so difficult to develop — the babies are hard to feed.

Some species hatch at a larger, more developed stage and can eat small crabs or shrimp almost right away. The giant Pacific octopus is one example. Others hatch tiny and drift as plankton for weeks or months.

How Much Does an Octopus Eat?

Octopuses eat a lot relative to their size, though exact amounts vary widely by species and water temperature. A hungry octopus can eat prey equal to a meaningful share of its own body weight in a single feeding. The giant Pacific octopus, one of the largest species, is known to take substantial meals — whole crabs and large clams.

Feeding frequency is not well standardized in the scientific literature. What is clear is that octopuses are efficient predators with high metabolic demands, and they eat when prey is available. Some species go without food for extended periods, especially females guarding eggs.

A female octopus that lays eggs typically stops eating and stays with the eggs until they hatch. For many species, she dies shortly after. This is a well-documented life cycle pattern, not a sign of illness.

Why the Octopus Diet Matters

Understanding what octopuses eat matters for more than curiosity. Octopuses are important predators in coastal ecosystems. They help control crab and clam populations, and they are prey themselves for seals, dolphins, eels, and large fish.

The growing interest in octopus farming has made diet research more urgent. Because so many species have delicate, hard-to-feed babies, large-scale farming has mostly failed to get off the ground. Some researchers and animal welfare groups have raised concerns about whether octopus farming can be done humanely at all, given how intelligent and solitary these animals are. That debate is ongoing and not settled.

For most readers, the takeaway is simpler. An octopus eats what it can catch and crack open, mostly shellfish and crustaceans, with fish and other octopuses on the menu when the opportunity arises. It is one of the ocean’s most adaptable hunters, and its diet reflects that.