Starfish, also known as sea stars, are some of the most fascinating creatures in the ocean. With over 1,500 species living in tide pools, coral reefs, kelp forests and deep-sea environments, they play an important role in marine ecosystems. Their bodies may look simple, but their feeding habits reveal a highly specialized lifestyle adapted to life on the seafloor. Understanding what starfish eat provides insight into how they survive, how they hunt without eyes or a brain, and how they help maintain balance in ocean habitats.
Starfish are opportunistic predators and scavengers. They feed using tube feet, sensory cells and a unique feeding mechanism that allows them to push their stomachs outside their bodies to digest prey externally. This ability lets them eat organisms many predators cannot access, such as bivalves tightly sealed in shells. While some species eat mostly plants or detritus, many are carnivores that actively hunt small animals on the seafloor.
This guide explores 20 wild foods starfish eat most, detailing how these ancient animals locate prey, capture food and sustain themselves across diverse ocean environments.
Understanding the Starfish Diet
Starfish are mostly carnivorous, although some species lean toward omnivory or scavenging. Their diet depends heavily on habitat. Rocky shore starfish feed on mussels and barnacles, while deep-sea species may eat sponges or small crustaceans. Starfish detect chemicals in the water, sensing prey through tiny receptors on their arms. Their slow movement hides surprisingly effective predatory techniques.
Perhaps the most remarkable feature of starfish feeding is their external stomach. When eating shellfish, a starfish uses its tube feet to pry open shells just enough to insert its stomach. It then releases digestive enzymes, dissolving the prey before pulling the liquefied tissue inside. This method allows them to consume food much larger or harder than their mouths would normally allow.
Because starfish are vital predators in many ecosystems, their feeding behavior helps keep populations of mollusks, barnacles and other invertebrates in check. Without starfish, many coastal habitats would become overrun by fast-reproducing prey species, altering the entire food chain.
20 Wild Foods Starfish Eat Most
1. Mussels
Mussels are one of the most important foods for predatory starfish, especially species living in rocky intertidal zones. Their dense colonies make them easy for starfish to find even in rough waters or during tidal shifts. Starfish detect the chemical signals mussels release into the water and move toward these clusters slowly but deliberately.
Once they reach a mussel, starfish anchor themselves firmly with hundreds of tube feet that act like tiny suction cups. They apply constant, low-force pressure—sometimes for several hours—until the mussel’s shell opens slightly. This tiny opening is enough for the starfish to extend its stomach outward and begin dissolving the mussel’s internal tissues.
Because mussels attach strongly to rocks and rarely escape predators, they offer reliable, high-protein meals year-round. In many coastal ecosystems, starfish population health is closely linked to mussel abundance.
2. Clams
Clams spend much of their lives buried in sand or mud, but this does not protect them from starfish. Starfish use chemical receptors on their tube feet to detect the faint scent of clams as they feed or move water through their siphons. Even clams hidden several inches below the surface can be found this way.
After locating a clam, a starfish slowly digs around it using its flexible arms, pulling it upward until it is fully exposed. Then, using coordinated tube feet, the starfish pries the shell open just enough for digestion to begin. Because starfish do not need the clam to open wide, even tightly closed shells offer little protection.
Clams provide not only dense nutrients but also high moisture content, making them essential for starfish living in areas with fluctuating temperatures or long periods between tides.
3. Oysters
Oysters are among the toughest prey many marine animals attempt to eat, but starfish are uniquely adapted to consume them. Oyster reefs grow in tightly cemented masses that create entire microhabitats along shorelines and pilings. Their thick shells protect them from most predators—except starfish.
When feeding on oysters, starfish position their arms around the shell, especially near the hinge where pressure is most effective. Tube feet contract rhythmically, increasing tension until a narrow gap appears. Once the starfish inserts its stomach, powerful enzymes liquefy the oyster’s tissue within minutes.
Because oyster beds occur in nutrient-rich, productive waters, starfish that feed on oysters often grow faster and reproduce more successfully. This makes oyster predation a central part of many coastal food webs.
4. Barnacles
Barnacles appear nearly immovable thanks to their heavily calcified shells, but starfish have evolved strategies to access their soft insides. Barnacles grow in intertidal zones where constant waves, drying periods and predators make survival challenging. Yet starfish persistently target them, especially when other prey becomes scarce.
To feed on barnacles, starfish use tube feet to grip the plates surrounding the barnacle body. They apply slow mechanical force until they can pull apart or distort the plates enough to reach the inner tissues. Even small openings allow digestion to begin as the stomach envelops the barnacle.
Barnacles are nutritionally dense and available throughout the year, making them an important fallback food for starfish when shellfish beds are depleted or during winter.
5. Snails
Snails are slower and less protected than clams or oysters, which makes them convenient prey for starfish of all sizes. Starfish often flip snails upside down to expose the softer underside of the shell or the opening where the snail retracts its body.
Once positioned correctly, starfish extend their stomachs into the snail’s shell or dissolve tissue through the opening. Because some snails have operculums (a hardened “door” that closes the shell), starfish sometimes use long feeding durations to break down the barrier.
Snails offer a balanced mix of protein, minerals and fatty acids, supporting both growth and regeneration in starfish that frequently lose arms to predators or environmental hazards.
6. Sea Urchins
Sea urchins pose unique challenges with their sharp, rigid spines, but starfish such as sunflower stars and crown-of-thorns stars are efficient urchin predators. These starfish approach from below or at angles where spines are easier to manage.
Using flexible arms, they wrap around the urchin, slowly neutralizing its movement. Hundreds of tube feet help hold the urchin steady while the starfish brings its mouth into contact with the soft underside. Digestion begins quickly once the stomach extends outward.
Sea urchins are highly nutritious, rich in protein and lipids, and essential for starfish species that must store energy for rapid movement or long-distance foraging.
7. Small Fish
Although starfish cannot chase healthy fish, they readily consume injured, trapped or dead fish encountered in tide pools, reefs and shallow sandy areas. Their chemical receptors allow them to detect decaying tissue from a distance, guiding them to easy meals.
When feeding on fish, starfish wrap multiple arms around the body to keep it from floating away with waves or currents. Fish flesh dissolves quickly under digestive enzymes, enabling starfish to absorb nutrients efficiently.
These opportunistic meals offer protein, fats and trace minerals that can be scarce in rocky shore environments, especially during seasons with fewer shellfish.
8. Sponges
Sponges form dense growths across reef surfaces, cave walls and deep-sea cliffs, making them accessible for starfish that prefer stationary prey. Unlike mollusks, sponges have no defensive shell, allowing starfish to feed with minimal effort.
Starfish digest sponge tissue by slowly dissolving soft sections of the organism. Because sponges filter large quantities of water, they accumulate nutrients that become available to predators like starfish.
In areas where shellfish are limited, sponges serve as long-lasting, nutrient-moderate meals that sustain starfish populations through fluctuating food cycles.
9. Sea Cucumbers
Sea cucumbers are slow, soft-bodied animals that many starfish feed on, especially in sandy or reef habitats. Their flexible bodies allow starfish to engulf them partially or entirely, depending on the size of both predator and prey.
Starfish target the softer sections first, digesting tissues gradually. Some sea cucumbers can regenerate lost parts, meaning starfish may feed without immediately killing the prey—an unusual dynamic in the marine world.
Sea cucumbers are rich in water and minerals, making them especially valuable to starfish living in warm, drying tidal zones.
10. Coral Polyps
Coral polyps are tiny but nutrient-dense animals that starfish consume by extending their stomachs over living coral surfaces. Crown-of-thorns starfish are the most well-known predators of coral, capable of stripping large areas of reef in a short time.
Starfish feed by immobilizing the coral’s defensive stinging cells with specialized membranes on their stomach. Once digested, polyps provide concentrated nutrition that fuels rapid movement and reproduction.
Although coral predation is natural, excessive starfish numbers—often influenced by environmental stress—can harm coral reef health.
11. Bristle Worms
Bristle worms live deep within cracks, sand layers and coral rubble, making them harder to reach than many other prey. Starfish detect them using chemical receptors on their tube feet, sensing subtle trails that worms leave behind as they move. Even when worms hide inside narrow crevices, starfish can identify their presence by following these faint chemical signals.
When feeding, the starfish positions several arms around the hiding spot, waiting patiently for the worm to extend part of its body. The moment the worm emerges, starfish use flexible tube feet to trap it and prevent escape. Their movements are slow but precise, giving them the advantage over prey that relies on darting motion.
Because bristle worms are soft-bodied and rich in protein, they are ideal prey for both juvenile and adult starfish. Starfish digest these worms quickly, absorbing nutrients that support tissue repair, regeneration and growth.
12. Detritus (Decaying Organic Material)
Detritus—composed of decomposing plants, animals and microbial matter—forms a major part of the diet for many starfish species, especially those in deeper waters. Starfish glide slowly across sandy or muddy bottoms, using external stomach surfaces to absorb nutrients directly from the sediment.
This type of feeding is energy-efficient, allowing starfish to survive in low-food environments where active hunting would be too costly. Detritus also contains beneficial bacteria and micro-organisms that help supplement a starfish’s nutritional needs.
Because detritus accumulates continuously in marine habitats, it provides a stable food source year-round. This makes it vital for species that live below the photic zone or in areas with limited mobility.
13. Algae (Certain Species)
Although most starfish are carnivores, some species feed on algae, especially in warm shallow waters where plants are abundant. These starfish use tube feet to scrape algae from rocks, coral surfaces and seafloor structures. Their stomachs then dissolve the algae into digestible form.
Feeding on algae helps starfish maintain hydration while accessing steady carbohydrates and minerals. This is particularly valuable during dry tidal cycles or in regions where carnivorous prey becomes limited seasonally.
Algae consumption also plays a role in preventing excessive algae growth in coral reefs and tide pools, helping maintain ecological balance.
14. Planktonic Particles
In their early stages of life, starfish rely heavily on plankton to fuel rapid development. Larval starfish float freely in the water column, capturing microscopic plankton using hair-like structures called cilia. This feeding method allows them to extract energy from particles much smaller than the prey they eat as adults.
Plankton provides essential nutrients, including proteins, fats and minerals that support early tissue formation. Larvae must consume high quantities to survive the vulnerable planktonic stage, which lasts days to weeks depending on species.
As they grow larger and settle onto the ocean floor, starfish gradually transition to hunting and scavenging. Plankton serves as the foundation for their early growth and long-term survival.
15. Sea Anemones (Small)
Some starfish species specialize in feeding on small sea anemones, despite their stinging tentacles. Starfish approach from below or the sides, where tentacles are less effective, and use tube feet to anchor the anemone’s body. This prevents the anemone from contracting or escaping into crevices.
Once immobilized, the starfish extends its stomach to envelop the anemone’s soft tissues, neutralizing stinging cells with digestive enzymes. This external digestion quickly breaks down the anemone into absorbable nutrients.
Sea anemones provide protein-rich meals found mainly in rocky reef environments, supporting starfish during periods when shellfish or worms become less abundant.
16. Shrimp (Dead or Weak)
Starfish frequently feed on shrimp that are dead, injured or too weak to swim effectively. Their keen chemical sensing allows them to detect decaying shrimp from a distance, guiding them toward these high-value food sources.
Once located, starfish wrap their arms around the shrimp to keep it from drifting away in currents. External digestion begins immediately, breaking down soft tissues into nutrient-rich fluids. Shrimp flesh offers higher fats and proteins than many other foods starfish encounter.
This scavenging behavior is essential in deeper areas or seasonal periods when live prey becomes scarce, helping starfish meet nutritional needs without expending excess energy.
17. Juvenile Crabs
While adult crabs are too agile and well-armored for starfish, juveniles are vulnerable prey. Young crabs often hide in tide pools, sandy pockets or reef crevices—places starfish search regularly. Their softer shells make them easier for starfish to digest.
Starfish trap juvenile crabs by encircling them with multiple arms and immobilizing their limbs using tube feet. Once subdued, the starfish extends its stomach over the crab, dissolving tissues quickly.
These nutrient-dense meals are especially beneficial during late spring and summer when juvenile crabs are abundant, providing key energy for starfish growth and regeneration.
18. Tube Worms
Tube worms anchor themselves inside protective tubes made of calcium or hardened mucus, but starfish have adapted ways to reach them. Using sensitive tube feet, starfish detect movement or feeding activity within the tube, signaling when the worm is near the opening.
Starfish then wrap their arms around the tube and apply slow, steady pressure to extract the worm or force it partially out. Even slight exposure is enough for digestion to begin as the starfish’s stomach envelopes the protruding body.
Tube worms provide long-lasting, concentrated nourishment that supports starfish living in reef crevices or deep-water zones where prey availability fluctuates.
19. Jellyfish Fragments
Although jellyfish are not typical prey, starfish consume jellyfish fragments when they drift into tide pools or snag on reefs. These pieces are easy to digest and contain water, minerals and small amounts of protein.
Starfish absorb jellyfish remains by extending their stomachs directly onto the soft tissue. Because the flesh breaks down quickly, digestion requires minimal effort or energy expenditure.
This opportunistic feeding becomes especially important during jellyfish blooms, when large quantities of fragments wash ashore or settle in shallow waters.
20. Carrion (Decaying Animals)
Carrion is one of the most important fallback foods for starfish, particularly in deep-sea environments where live prey can be scarce. Starfish detect the scent of decaying fish, shellfish or other marine animals and move toward the source using chemical signals.
Once they reach the carcass, starfish use multiple arms to anchor themselves and begin external digestion. This method allows them to consume large amounts of nutrient-rich material without requiring active hunting.
Carrion scavenging helps recycle nutrients back into the marine ecosystem, making starfish essential contributors to ocean health and decomposition cycles.
FAQs About What Do Starfish Eat
Are starfish carnivores?
Most are carnivores, though some eat algae or detritus.
How do starfish eat shellfish?
They pry shells open with tube feet and digest prey using an external stomach.
Do starfish eat fish?
They eat dead or weakened fish but cannot chase healthy fish.
What do baby starfish eat?
Larvae eat plankton and microscopic organic particles.
Do starfish eat coral?
Some species, like the crown-of-thorns, eat coral polyps.
Do starfish eat algae?
A few species consume algae, especially in shallow waters.
How often do starfish eat?
Often, but their digestion is slow and depends on prey availability.
Do starfish chew food?
No. They dissolve and absorb food externally.
Do starfish eat urchins?
Yes, several species hunt sea urchins.
Are starfish scavengers?
Many species scavenge, especially in deep-sea regions.
Final Thoughts
Starfish may appear simple, but their feeding habits are some of the most unique in the animal kingdom. By consuming mussels, clams, barnacles, worms, detritus and other small marine animals, they help maintain ecological balance in oceans worldwide. Understanding what starfish eat reveals how essential these creatures are to coral reefs, rocky shores and deep-sea habitats. Their remarkable external digestion and adaptive hunting techniques highlight just how specialized and resilient starfish truly are.
