Every octopus species is a predator. All octopuses are carnivorous, feeding on live animals ranging from tiny crabs and shrimp to fish, clams, and even other octopuses. They sit in the middle of marine food webs, hunting smaller creatures while being hunted themselves by sharks, seals, and large fish. What makes them remarkable isn’t just that they hunt, but how they do it.
What Octopuses Eat
The typical octopus diet reads like a seafood menu: shrimp, crabs, clams, scallops, lobsters, mussels, and small fish. The giant Pacific octopus, one of the largest species, eats all of these and has been known to scavenge larger fish and even seabirds. Smaller species focus on whatever prey fits their size, but the pattern holds across all known octopuses. None are herbivores or filter feeders.
Octopuses eat a lot relative to their body size. In feeding studies on the common octopus, individuals consumed between 1.3% and 4.7% of their body weight per day. That high intake fuels a fast metabolism and rapid growth, which is necessary for animals that typically live only one to two years. Every calorie comes from other animals.
Even baby octopuses are predators from the start. Paralarvae, the tiny planktonic young of the common octopus, feed heavily on larval crabs (which made up roughly half their diet in studies off the Iberian Peninsula), along with copepods, jellyfish relatives, krill, and small fish. As they grow and drift from coastal to open waters, their diet shifts toward open-ocean prey like krill and small drifting organisms. Researchers analyzing their feeding patterns found them to be selective predators rather than indiscriminate filter feeders, showing clear preferences among the 26 prey groups evaluated.
How Octopuses Hunt
Octopuses use two broad strategies depending on the situation. When prey is visible, they rely on excellent eyesight and rapid color-changing camouflage to stalk and ambush. Specialized pigment cells in their skin allow them to match their surroundings almost instantly. Studies of octopuses outside their dens show that they keep a high proportion of these cells active most of the time, effectively remaining invisible as they move across the seafloor.
But vision is only half the story. In the wild, octopuses spend much of their foraging time reaching their flexible arms into crevices, under rocks, and through coral where they can’t see at all. This blind hunting works because the suckers lining each arm double as taste organs. Research published in 2022 confirmed that octopuses can distinguish prey from non-prey using only these contact taste receptors, without any help from sight, smell at a distance, or touch. When suckers contacted extracts from prey animals, the arms spent significantly more time exploring and curling around the source compared to non-prey substances. This means an octopus literally tastes its way to dinner in the dark.
Once prey is located, the octopus envelops it with the webbing between its arms, forming a tent-like structure called a “web-over” that traps the animal against the seafloor. From there, the octopus uses its hard, parrot-like beak to crack shells or bite into flesh.
Venom as a Hunting Tool
Most people associate octopus venom with the blue-ringed octopus, and for good reason. This small Australian species delivers a bite containing tetrodotoxin, the same potent nerve poison found in pufferfish. It works by blocking the electrical signals that travel along nerves, causing rapid muscle paralysis in prey. The bite itself is nearly painless, just two small puncture marks, but the toxin can paralyze a crab in seconds.
Blue-ringed octopuses are extreme cases, but they aren’t the only venomous ones. The common octopus produces its own neurotoxin called cephalotoxin, and current evidence suggests that most if not all octopus species use some form of venomous saliva to subdue prey. When an octopus bites into a crab or clam, it injects saliva that helps break down tissue and weakens the animal’s ability to resist. For hard-shelled prey like clams, some species also drill a small hole through the shell with a rough, tongue-like structure before injecting the venom inside.
Intelligence in the Hunt
Octopuses are widely regarded as the most intelligent invertebrates, and their hunting reflects that. They learn from experience, remember the locations of productive foraging spots, and adjust their strategies based on the type of prey. Individual octopuses show measurable differences in problem-solving ability, meaning some are simply better hunters than others.
They also use tools. The veined octopus, found in Indonesian waters, was documented carrying coconut shell halves across the seafloor and later assembling them into a shelter, a behavior that meets the scientific definition of tool use. While this particular example is defensive rather than predatory, it illustrates the kind of flexible planning that octopuses bring to all their interactions with the environment, including finding food that’s hidden or hard to access.
Octopuses as Cannibals
Octopuses will even prey on their own kind. The first documented observations of cannibalism in wild common octopuses, filmed by divers off the coast of Spain, revealed several consistent patterns. Attacks were made by both males and females. The prey was always from a different age group and smaller, typically 20% to 25% of the predator’s body weight. In two of the three filmed encounters, the attacker dragged the victim back to its den before eating. And perhaps most notably, the predators started by consuming the tips of their victim’s arms.
What surprised researchers was that cannibalism occurred even when other food, specifically mussels, was readily available nearby. This suggests the behavior isn’t purely driven by hunger. Territory defense, competition, and the high nutritional value of eating a fellow octopus all likely play a role.
Where Octopuses Fit in the Food Chain
Octopuses are mesopredators, meaning they occupy a middle tier in ocean food webs. They control populations of crabs, shrimp, and shellfish below them while serving as high-calorie meals for predators above them, including moray eels, dolphins, seals, sharks, and seabirds. In many coastal ecosystems, octopuses are a key link connecting the bottom of the food web to its top.
Their short lifespans and fast growth rates make them especially responsive to changes in their environment. When conditions are good, octopus populations can boom quickly, putting significant pressure on the shellfish and crustaceans they feed on. When populations crash, their predators feel the loss. This combination of high consumption, rapid reproduction, and short lives gives octopuses an outsized ecological influence for their size.