What Do Hermit Crabs Eat? — A Scientific Look at Their Diet in the Wild and Captivity

Hermit crabs are fascinating crustaceans known for inhabiting discarded shells to protect their soft, vulnerable abdomens. There are over 800 species of hermit crabs, found in both terrestrial and aquatic environments. Though they are often seen as low-maintenance pets or quirky beach dwellers, their dietary habits are surprisingly diverse and vital to their health and ecosystem role. This article explores what hermit crabs eat at different life stages and environments, and how to provide a balanced diet for those kept in captivity.

1. General Feeding Behavior of Hermit Crabs

1.1 Scavengers by Nature

Hermit crabs are omnivorous scavengers. They feed on a wide range of organic matter found in their environment, helping to clean up debris and decaying material.

1.2 Nocturnal Foragers

Most hermit crabs are active at night, using their sensitive antennae to locate food under cover of darkness.

2. What Do Wild Hermit Crabs Eat?

2.1 Marine Species

Marine hermit crabs, commonly found in tidepools and coral reefs, feed on:

• Algae

• Small fish remains

• Mollusk scraps

• Detritus (decomposing organic matter)

• Microscopic plankton

2.2 Terrestrial Species

Land hermit crabs consume a mix of plant and animal material:

• Fallen fruits and leaves

• Tree bark

• Dead insects or small animals

• Bird or reptile droppings (a source of calcium and protein)

2.3 Opportunistic Feeders

Hermit crabs will eat almost anything they find that is edible, including bits of carcasses, eggs, or discarded shells with organic residue.

3. Nutritional Needs of Hermit Crabs

3.1 Balanced Diet Components

A healthy diet for hermit crabs includes:

• Proteins: insect larvae, fish flakes, cooked meats

• Carbohydrates: fresh fruits and vegetables, whole grains

• Calcium: essential for exoskeleton development; sources include crushed eggshells, cuttlebone, coral sand

• Fatty acids: found in seeds, nuts, and some fish

3.2 Importance of Variety

Feeding a varied diet ensures all nutritional bases are covered and prevents boredom in captive crabs.

4. Feeding Hermit Crabs in Captivity

4.1 Commercial Foods

There are hermit crab-specific food products that contain essential nutrients. However, these should be supplemented with fresh, whole foods.

4.2 Safe Foods for Pet Hermit Crabs

• Apple slices, banana, mango, grapes

• Leafy greens (e.g., kale, spinach)

• Fish flakes, bloodworms, brine shrimp

• Cooked chicken or eggs (unseasoned)

4.3 Foods to Avoid

Avoid feeding hermit crabs the following:

• Processed human food (salty, sugary, or fried)

• Onions, garlic, citrus fruits (irritating to their digestive system)

• Raw beans or potatoes (toxic in raw form)

5. Feeding Frequency and Tips

5.1 Daily Feeding

Offer fresh food once per day and remove uneaten portions after 12–24 hours to prevent mold and bacteria.

5.2 Hydration

Provide both freshwater and saltwater in shallow, non-metallic containers. Hermit crabs need both for drinking and shell soaking.

5.3 Food Presentation

Hermit crabs use their claws to pick up and manipulate food, so food should be cut into small, manageable pieces.

6. Seasonal and Life Stage Considerations

6.1 Molting Phase

During molting, hermit crabs often bury themselves and may not eat for days or weeks. Do not disturb them during this time.

6.2 Growth Periods

Juvenile and actively growing crabs require more protein and calcium to build their exoskeleton.

6.3 Reproductive Season

Energy-rich foods like seeds, nuts, and fruit help support reproductive health in mature crabs.

7. Ecological Role of Hermit Crab Feeding

7.1 Nutrient Recycling

By feeding on decomposing material, hermit crabs return nutrients to the ecosystem and help prevent disease buildup.

7.2 Supporting Biodiversity

Their foraging helps maintain beach and reef cleanliness, benefiting other marine and coastal species.

8. Conclusion: Feeding for a Healthy Crab and a Healthy Ecosystem

Hermit crabs may be simple creatures, but their dietary needs are complex and essential for their survival and environmental function. Whether in the wild or in a terrarium, these scavengers require diverse, nutrient-rich diets to thrive. Understanding what hermit crabs eat allows us to support their health, appreciate their ecological contributions, and promote better captive care practices.

animal tags： Hermit-Crabs