February 16

What Do Crabs Eat, Do You Know?


Keeping a crab as a pet may be a pleasant and exciting experience.

However, if you want to keep crabs as pets, you will need to know how to properly care for them, including what foods to give them.

So, the question now is, what do crabs eat?

The diet of a crab may include food items such as fish, worms, algae, and shrimp.

There are many kinds of crabs, each with its own particular diet. The vast majority of crabs consume both plant and animal matter; however, larger crabs may specialize as carnivores. Smaller crabs can eat plants. Some species of crabs are known as scavengers because they will consume dead animals as well as vegetation.

Tip: The diet of a crab might change depending on its size and age. Continue reading this article if you are interested in learning more about the dietary habits of crabs.

Crabs Habits And Biology

Crabs are decapod crustaceans that belong to the order Decapoda, which includes other species such as lobsters, shrimps, and crabs.

In saltwater and freshwater environments, crabs are found in all parts of the world.

Crabs typically live in burrows, under rocks, crevices, and tree trunks, depending on the species. They feed on various food sources, including small fish, algae, mollusks, and other crustaceans.

Crabs display a wide range of behaviors, depending on the species. These behaviors range from scavenging to social interactions and cooperation. For example, some crabs form mass migrations, while others form protective groups. Crabs also communicate using pheromones and vibrations.

The average lifespan of a crab is between two and four years, though some species have been known to live much longer. Crabs have a complex life cycle, with an egg stage, a larval stage, and an adult stage. The egg stage typically lasts about two weeks, followed by a larval stage for several months. During the larval stage, the crabs shed their shells multiple times before adulthood.

Overall, crabs are fascinating creatures that have adapted to many different environments and can be studied to better understand their habits, lifestyle, and biology.

The Crab Diet

As mentioned above, the diet of a crab may include food items such as fish, worms, algae, and shrimp.

Let’s discuss all of them in detail.

Shrimp, Prawns, and Krill

A larger crab’s diet comprises around 17% shrimp, krill, and prawns. But, overall, crabs enjoy shrimp because it is rich in protein, low in fat, and provides essential nutrients, including omega-3 fatty acids and calcium. 

Small Fish

The crabs frequently go on fishing expeditions in search of small fish, which may make up as much as 10% of their food. Crabs will also consume dead fish left on the seafloor during low tide.

    Crabs are slower than fish; thus, they have developed various eating strategies to consume them. They hunt for fish that are ill or weak to trap them since these fish are weaker and don’t move as quickly. They often forage for smaller fish since larger fish, like salmon, are their natural predators. 

    Seaweed and Algae

    Herbivorous tiny crabs frequently use seaweed as their food source. Many crabs, especially the smaller ones that cannot eat out all the time, would love this easy food source.

    Crabs consume algae frequently as a second source of food. Mainly, little herbivore crabs feed only on algae. These crabs consume a variety of algae, including brown, red, and green types.

    These algae are consumed by crabs living in both saltwater and freshwater areas. It does not take much effort for a crab to seek down and consume these algae, so they go for it.

    Small Clams and Mussels

    Larger species of crabs, such as king crabs, can consume the smaller clams and mussels. They will occasionally consume other species with hard shells, like sea urchins, on occasion.

    They find these animals by using their sense of smell. In addition, they rely on their taste buds and will move about the ocean floor to locate them.

    Crabs may get the essential nutrients they need from clams, which helps them maintain their health. Omega-3 fatty acids, vitamin B12, and essential fatty acids are all included.

    Squid and Whelks

    Crabs like the Dungeness crab can consume bigger prey items like squid and whelks because of their size. The protein content of squid and whelks is higher than that of most other smaller animals, and they also include a respectable quantity of iron and calcium and are rich In vitamin C.


    Larger crabs consume smaller crabs and other crustaceans like lobsters and crayfish. Crabs such as blue crabs, king crabs, and snow crabs are included in this category.

    The number of nutrients that crabs receive from their prey, crustaceans, might vary depending on the species.

    Dead Animals

    Some crabs love to eat decaying materials and dead animals, including dead fish and shrimp, among other things. They prefer to forage for dead meat rather than hunt because of their poor eyesight and slow movement.

    How Do Crabs Collect Food and Hunt?

    Crabs have a variety of hunting and foraging strategies that they employ to collect food. One of the most common methods is foraging, where the crab will search for food on the ocean floor or among the vegetation in its environment.

    Additionally, some crabs use their powerful claws to capture and eat small fish, mollusks, and other sea creatures. Crabs may also scavenge for dead or injured prey or even hunt in groups to increase their chance of success.

    How Much Do Crabs Eat?

    Crabs only eat small amounts of food at a time. They eat whenever they find food, but it’s usually not enough. As a result of the absence of teeth, they cannot consume a substantial quantity of food at one time or take significant portions of food when they do. Crabs have an anatomy that makes breaking down food in their jaws more difficult. Therefore, crabs benefit from ripping their food and consuming it in smaller chunks.

    On average, a crab consumes about 5-10% of its body weight daily.

    However, in the wild, crabs may eat more or less depending on the availability of food sources. This is why crabs only have to be fed twice a day if you are trying to feed them.

    What Do Crabs Like To Eat Most?

    The vast majority of crabs are carnivorous predators and scavengers, just like fish, other crustaceans, shrimp, and several other tiny creatures. Despite this, their diets often consist of various foods, including several alternatives to meat. Some crabs eat meat, others don’t, but most species eat everything.

    However, the types of food a crab will prefer will depend on the species and the availability of food sources.

    What Does The Smallest Crab Eat?

    The smallest crab in the world is the pea crab (Pinnothera Faba), which measures less than an inch. These tiny crustaceans usually eat zooplankton, protozoa, and algae.

    What Does The Largest Crab Eat?

    The largest crab is the Japanese spider crab (Macrocheira Kaempferi). This species has a leg span of up to 3 meters and can weigh up to 19kg. While these crabs can live in both fresh and salt water, they prefer the latter and are typically found in depths of up to 200 meters.

    Japanese spider crabs are omnivorous, meaning they eat plants and animals. Their diet consists mainly of mollusks, sea urchins, and other crustaceans. They have also been identified to feed on carrion and decaying plant matter, as well as scavenge for food on the ocean floor.

    Do Crabs Eat Dirt?

    Well yes! Some carbs species, such as fiddler crabs, usually eat a small amount of sand or mud. They do this using specialized jaws that allow them to push any food, such as algae, out of the soil.

    Foods To Avoid Feed Crabs

    Crabs are sensitive to dietary changes and should not be fed too much of the same food. Generally, it is best to avoid feeding crabs foods that are high in carbohydrates, fat, or sugar.

    Such foods include processed meats, sweets, and food containing preservatives, artificial colors, and flavors. Additionally, it is best to avoid raw meats and fish as they may contain parasites or bacteria that can be harmful to the crab.

    Tips For Feeding Crabs

    Feeding a crab is relatively easy and can be done in a few simple steps:

    • First, make sure to have a variety of fresh and frozen seafood, vegetables, and fruits on hand.
    • If using fresh seafood, it should be thoroughly cooked.
    • To avoid tank fouling, crabs should always have food in shallow dishes.
    • Chop the food into smaller pieces and place them into the tank, either directly or in a feeding dish.
    • You may feed them a commercially available dried crab flake or pellet.
    • At the very least, fresh vegetables and fruits like apples, carrots, bananas, and kale should be provided twice a week.
    • Crabs also accept dried mealworms and crickets coated in calcium and vitamins.

    Final Thoughts

    Crabs consume anything they can get their claws on. They consume a diverse variety of foods, including vegetables, crabs, and fish. Each kind of crab has its own unique diet, which is based on the food that is available in its habitat.


    What can crabs not eat?

    Crabs should not be fed certain foods that can be harmful to them. These include processed meats, such as bacon, sausage, and hot dogs; sweets, such as cake, candy, and cookies; and any food containing preservatives, artificial colors, or flavors.

    Do crabs eat plankton?

    Yes, crabs are omnivores and eat various foods, including plankton. In the wild, crabs can feed on multiple planktonic creatures, such as zooplankton and phytoplankton. In captivity, plankton can be supplemented with commercially prepared foods, such as frozen shrimp or fish.

    What do crabs like to eat the most?

    Crabs have a varied diet and will eat a wide range of foods. Some most commonly liked items include small shrimp, fish, clams, mussels, earthworms, snails, and other crustaceans. Additionally, crabs will seek out food sources in their environment, such as decaying plants or animals, and hunt these for nutrition.

    What do saltwater crabs eat?

    Saltwater crabs are primarily carnivorous but also opportunistic omnivorous, meaning they will feed on animal and plant material. Some of the most common foods they will feed on are small fish, crustaceans, shrimp, and prawns. They will also feed on various types of algae, such as green hair algae and cyanobacteria. Saltwater crabs can be fed dried seaweed, pellets, or meaty foods in captivity.

    Do crabs eat seaweed?

    Yes, crabs can eat seaweed. Seaweed is a rich source of nutrients and vitamins and can benefit a crab’s diet. Seaweed can be fed to crabs in dried seaweed, fresh seaweed, or prepared foods containing seaweed.

    What do you feed pet crabs?

    Pet crabs should be fed various foods to ensure they get all the necessary vitamins and minerals. Some of the most commonly used foods for pet crabs include shrimp, fish, worms, snails, clams, oysters, mussels, squid, and other meaty foods. Additionally, crabs can feed on various prepared foods containing multiple ingredients. Pet crabs can also be fed boiled vegetables, fruits, pellets, or other commercial crab diets in captivity.

    Do crabs eat fish?

    Yes, crabs can eat fish. Fish is an excellent source of protein, fatty acids, and other essential vitamins and minerals for crabs. Most crabs feed on small fish, such as minnows, guppies, barbs, and another fish fry.

    Do crabs eat humans?

    No, crabs do not eat humans. Crabs are carnivorous and feed on other sea creatures, such as fish, mollusks, worms, and crustaceans. However, some types of crabs may scavenge for dead or injured creatures, including humans. However, this behavior is not common among crabs and is not considered a significant threat to humans.


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