What do crabs eat?

In this brief article, we will answer the question, “What do crabs eat?”, and provide information on whether crabs are omnivores or if they are parasites, what crabs eat as well as the significance of a crab’s diet.

What do crabs eat?

Crabs eat shrimps, algae, worms, and fish. Usually, the crabs would attack ones that are smaller than them. This would include smaller fishes, smaller crabs, and crustaceans. Some of the crustaceans would include shrimps, prawns, and krills.

Squids can be consumed by some bigger crabs as well. Red king crabs have bigger claws to help catch prey and kill them with sharp claws. There are crabs that also search for dead animals or other organic matter. 

These are called scavengers. Scavengers would consume anything dead that is present on the ground.

Are crabs omnivores?

Yes, crabs are typically omnivorous in nature. Crabs that are smaller in size would consume shrimps, clams, seaweed, worms, and algae. Larger crabs on the other hand can consume mussels, snails, crabs, and small fishes. 

There are many other crab species too. Some crabs consume starfish and barnacles. Some of the commonly consumed animals would include smaller fish, carrion, crustaceans, clams, algae, mussels, and whelk.

Can crabs be parasites?

Smaller crabs called pea crabs can be parasites. This is because it can live inside mussels or mollusks. When the mussels catch phytoplankton, the pea crabs would take in some of the pea crabs for themselves.

Mussels also have a hard outer body in the form of a shell. This shell would help protect the pea crab. 

As a result, the pea crab has a parasitic relationship with the mussel or mollusk. However, the oyster does not suffer any harm as a part of this relationship.

How do crabs eat?

Crabs are not choosy in terms of eating and they would eat whatever comes their way. The claws of the crabs can be used to grab or kill the prey. The prey would then be put into the mouths. 

The claws of the crabs would act like the hands of the humans. The claws can also be used to break the food particles into smaller pieces. These smaller pieces of food would then be placed inside the mouth of the crabs.

Sometimes, the prey consumed by the crabs can have a stronger shell. The crabs can break through these shells using their claws. The strong claws can help in quickly grabbing the prey to prevent them from escaping.

What is the significance of a crab’s diet?

Crabs consume many foods. The significance of consuming them is given below:

  • Smaller fish can be found in the water bodies. They would make a small portion (10 percent) of the crab’s diet. 

This is because it can be difficult to catch fish for crabs. Fishes are faster than crabs and escape being killed. So the ones that are dead or injured and lying on the ocean floor would be usually consumed by the crabs.

Fish provides energy to the crabs. It can also provide vitamins A, D, E, and K to the crabs too.

  • Crustaceans can include smaller crabs, barnacles, lobsters, or crayfish. It can make up 17-18 percent of a blue crab’s food. Crustaceans, particularly lobsters, would contain a good amount of calcium, iron, and vitamin A.
  • Shrimps contain a good amount of protein and include 17 percent of a Snow crab’s diet. Shrimps are also a good source of Omega-3 along with fat and calcium.
  • Dead fishes or animals can be a major portion of the crab’s diet. This is because they are easy to catch. Some of the crabs are particularly scavengers too. The fish would contain protein, fat, vitamins, and iron.
  • Squids and whelks can be another food that could be consumed by crabs. Larger crabs tend to consume squids. However, dead squids would be commonly consumed by bigger crabs.

Calcium, iron, and vitamin C would be present in the squids. This would make them suitable enough to be consumed by crabs.

  • Small mussels or clams can make up another part of the crab’s diet. A good amount of vitamin B12 and Omega-3 can be obtained after consuming them.
  • Algae and seaweed can be consumed commonly by smaller crabs. Algae is also easier to consume as, unlike other prey, a crab does not have to run and then catch them.

Crabs can either scrape the algae off or use their claws to pick them and consume them. Algae can help remove toxins from the crabs as well.


In this brief article, we have answered the question, “What do crabs eat?” and provided information on whether crabs are omnivorous, whether crabs are parasites, what crabs eat as well as the significance of a crab’s diet.


Leave a Comment