With their eight flexible arms, ability to change color and texture to camouflage, and remarkable intelligence, octopuses captivate the imagination. Their alien appearance and strange behaviors leave many wondering – what do these cephalopods eat?
If you’re short on time, here’s a quick answer to your question: Yes, octopuses are carnivores. They prey on crustaceans, mollusks, and fish using their sharp beak and venomous saliva.
In this approximately 3000 word article, we’ll take an in-depth look at the octopus diet and feeding habits. We’ll cover what they eat in the wild, how they hunt and capture prey, their unique adaptations that make them effective predators, how much and how often they eat, and more.
Octopuses are Strictly Carnivorous
They prey on crustaceans, mollusks, and fish
Octopuses are strictly carnivorous and feed on a variety of marine animals including crustaceans like crabs, lobsters and shrimp which make up 50-80% of their diet depending on location and availability (1).
They are also known to prey on mollusks like clams, snails and shellfish which are common food sources. Small fish and other swimming cephalopods like squids are also on the menu.
According to a 2018 study, more than 168 different species were found to be prey items in octopus diets. The exact diet composition varies by habitat but always consists entirely of meat from other animals.
Octopuses have a sharp beak and venom to subdue prey
Octopuses have excellent hunting abilities aided by specialized features. They have a sharp, parrot-like beak which easily cracks through the hard shells of crustaceans and mollusks (2). They also produce venom which contains neurotransmitters like acetylcholine and tachykinins that paralyze prey (3).
The saliva covers the prey while the sharp beak tears it into pieces which are then passed to the mouth using the suckers. This allows them to feed on armored shelled animals much larger relative to their own body size.
Their hunting strategies are varied and complex
Octopuses are very intelligent and use complex, versatile hunting techniques like:
- Mimicry – changing skin color/texture to stealthily approach prey
- Ambush – pouncing suddenly on unsuspecting prey
- Trapping – barricading prey exits from crevices before attacking
They are very adaptable hunters taking advantage of local conditions and prey behaviors. As solitary animals they rely completely on their own cunning skills for survival.
A Closer Look at the Octopus Diet in the Wild
Crabs, lobsters, and shrimp are common prey
Octopuses are formidable hunters that feast on a variety of shellfish, especially crabs, lobsters and shrimp. Using their flexible bodies, octopuses can squeeze into tight spaces like rock crevices to snatch hiding crustaceans.
Their beak-like jaws can easily crush thick shells to access the meat inside. Research shows that in certain habitats, crabs account for 25-40% of an octopus’s diet.
They eat bivalves like clams and mussels
Shelled mollusks like clams, oysters and mussels are another crucial food source. An octopus will use its dexterous tentacles to pry open the two shells of a bivalve. Its sharp radula (a tongue-like organ covered in teeth) rasps the flesh loose.
Studies reveal up to 60% of an octopus’s energy intake can come from bivalves in certain ecosystems.
Fish are an important part of their diet
While shellfish are a staple prey, fish are another major food source. Using stealth and stalking tactics, octopuses ambush all varieties of fish. Their extreme flexibility allows them to reach into tight spaces like coral reefs to grab hiding fish.
Research from Hawaii reveals wild octopuses can meet up to 84% of their metabolic needs by preying on fish.
Some species hunt other cephalopods and polychaete worms
Though not all octopuses are cannibalistic, some species do prey on each other, especially on juveniles and eggs. Squid and cuttlefish are also on the menu for large octopus species. Sneaky octopuses might even steal bait right from fishing lines.
Polychaete worms (bristle worms) are another target – octopuses probe crevices and rubble hunting for these small worms. One study in California found that the GIANT Pacific octopus meets 42% of its yearly dietary needs by eating polychaetes and other worms.
They occasionally cannibalize other octopuses
There are accounts of cannibalism among octopus species, though it is still uncommon. Large adults sometimes eat smaller juvenile octopuses if food becomes scarce. Females may also eat unattended eggs they come across.
As solitary creatures, coming into contact with each other usually leads to avoidance or aggression. A rare study in 2020 observed over 200 instances of cannibalism among Common octopuses in natural conditions over 4 years.
Unique Hunting Adaptations and Strategies
Their flexible bodies allow them to access hard-to-reach prey
Octopuses have extremely flexible bodies that enable them to squeeze into tight spaces that other marine predators cannot access. Their soft bodies can morph to fit cracks, crevices and narrow openings where prey like crabs and shellfish hide (Monterey Bay Aquarium).
Once an octopus locates prey in a hard-to-reach spot, it can use its dexterous arms and suckers to pull the prey back out.
Color changing camouflage helps them ambush prey
Octopuses are experts at camouflage and often rely on stealth ambush tactics when hunting. They can change their skin color, skin texture and body shape in the blink of an eye to seamlessly blend in with their surroundings like rocks or coral.
This allows them to lay in wait for unsuspecting prey to swim or crawl by.
Jets of water disorient prey and excavate dens
Octopuses have a siphon which they use to quickly expel jets of water from their bodies. They will aim these blasts of water at prey to shoot them out of rock crevices. The powerful streams also help excavate dens in the ocean floor where they dwell.
Some species use venom to paralyze prey
Around a third of octopus species produce venom that contains neurotoxins capable of paralyzing prey (Smithsonian Ocean). The most toxic venom is found in blue-ringed octopuses that contain enough toxin to kill adult humans.
They bite prey like fish and quickly inject venom that immobilizes them so they can be easily carried off to their den.
Intelligence aids complex hunting behaviors
Octopuses have surprisingly complex brains for invertebrates. Their advanced intelligence allows them to employ clever, intricate hunting strategies like unscrewing jar lids to reach prey inside (Scientific American).
They can problem solve, learn through observation, and even anticipate prey behaviors.
How Much and How Often Octopuses Eat
Food intake depends on species, size, and habitat
The amount and frequency of eating in octopuses varies greatly depending on the species, its size, and habitat. Giant pacific octopuses, which can weigh over 100 pounds, may eat just a few small crabs or shrimps per day.
By contrast, a tiny East Pacific Red octopus weighing only 50 grams could eat a dozen or more amphipods (small crustaceans) per day.
Octopuses living in nutrient-rich environments like coral reefs tend to eat less frequently than those in sparse habitats like the deep ocean floor. An octopus living near lots of prey needs to hunt less often than one searching for sporadic food sources.
Smaller octopuses eat more frequently than larger ones
Because of their higher metabolism, smaller octopuses need to eat more often than big ones relative to their body size. An octopus weighing 1 kg might eat 3% of its body weight per day, while a 10 kg individual might eat only 1% of its weight daily.
This reflects the fact that weight increases much faster than surface area as an octopus grows. But respiration and nutrient exchange occur through the surface area of the gills and skin. So smaller octopuses have higher caloric needs per unit of weight.
Some go extended periods without eating between meals
While active and hunting, most octopuses need to eat frequently. But some species can go remarkably long stretches without food when in energy conservation mode.
For example, the East Pacific red octopus typically fasts for 1-2 weeks while brooding her eggs. The deep sea Graneledone boreopacifica lives an astonishing 4.5 years by entering extended rest periods between meals.
Some octopuses enter a dormant state called senescence as they near death, subsisting only on stored body fat for their remaining weeks or months of life.
Octopus Diet in Captivity
Crab, shrimp, squid, and clams are common foods
Octopuses are carnivorous and subsist primarily on a diet of crab, shrimp, squid, and clams when kept in captivity, according to experts. These foods provide a balanced source of protein and nutrients that align with an octopus’s nutritional needs.
According to the Aquarium of the Pacific, when keeping octopuses, it’s important to offer a variety of seafood such as shrimp, clams, squid, and small fish. Crab is also an excellent food because octopuses use their beak to break through crab shells to access the meat inside.
The shells can help clean an octopus’s beak and wear it down.
Nutritional requirements must be met
An octopus’s health and wellbeing depends on meeting all of its nutritional needs. According to the Fisheries Research Blog, octopus paralarvae require certain percentages of protein, lipids, and other nutrients in their formulated diet plans. Imbalances can lead to high mortality rates.
Octopuses need nutrients like amino acids, fatty acids, vitamins and minerals. Formulated diets should contain over 45% protein, at least 14% lipids, and adequate amounts of vitamins like A, D and E, according to scientific publications.
Nutrient | Percentage in Diet |
Protein | >45% |
Lipids | >14% |
Overfeeding can be an issue in captivity
Though it’s important to meet an octopus’s dietary needs, overfeeding can become a problem in captivity according to aquarists. Since octopuses will generally eat whenever food is available, it can be easy to overfeed them if strict portions are not maintained.
The Octopus Den recommends feeding an adult octopus the size of one crab per week, divided into two feedings.
More frequent, smaller meals are ideal for younger, growing octopuses. Portion control avoids overfeeding issues.
Additionally, uneaten food should be removed promptly from the tank after each feeding to maintain clean water, according to octopus care guides. Allowing old food to accumulate can cause ammonia spikes.
Conclusion
With their flexible bodies, ability to change color and texture, and sharp beaks, octopuses are well-equipped for a carnivorous lifestyle. They are skilled and intelligent hunters that feed on a variety of marine animals including crustaceans, mollusks, and fish.
While octopus diets can vary by species, habitat, and size, they are exclusively meat eaters. Understanding the octopus as an effective predator provides insight into their evolutionary adaptations and unique place in marine ecosystems.