Do You Know What Crabs Eat? Find Out Now

What do Crabs Eat?
While most of the crabs are omnivores, some are strictly carnivores or herbivores.
Did you know that crabs chew their food inside the stomach? Their stomach walls are highly muscular with grooves and ridges. The raised tooth-like structures facilitate food processing. This part of the stomach is called gastric mill. Even the mouth parts of crabs are adapted to collect and tear food and push them into the esophagus. Though most of the crab species are aquatic, some are terrestrial. So the type of food they eat may vary with the species.

Most of the crabs are aquatic and so, a major part of their diet consists of algae. But they are not restricted to algae, as most of these crustaceans are omnivores. However, some species are carnivores and some others are strict herbivores (like mangrove crabs).

Most of the crabs eat plant and animal matter. There are some crabs that can be scavengers and eat dead animals. Coral crabs eat coral polyps found in the warm waters of the tropical oceans. The Ghost crabs and Fiddler crabs eat mud and sand on the beaches, but they filter and ingest food materials and throw out the mud. Pebble crabs and box crabs use their claws as tools to crack open marine snails. One of the colorful crabs, Sally Lightfoot or redrock crabs are found to feed mainly on algae, but they feed upon carcasses and even bird droppings occasionally. In short, these are some of the common things that crabs eat:
  • Worms
  • Fungi
  • Plankton
  • Bacteria
  • Molluscs
  • Shrimp
  • Barnacles
  • Krill
  • Crayfish
  • Detritus
  • Tiny turtle hatchlings
  • Partially decomposed plant or animal matter
These were some of the foods that crabs relish. They need a mix of plant as well as animal matter to grow healthy and survive better. In case of pet crabs, expert opinion must be sought, so as to understand what to feed.

What are the Parts of a Crab's Body?
Crabs are related to lobsters and shrimp, but as they have evolved, they were able to walk and run sideways. These creatures can also burrow in the sand and swim in the waters. They have a segmented body with many pairs of appendages. There are five pairs of appendages that are used for walking, two as a sensory antennae. The front legs have pincers known as chelae. These pincers are used for fighting, display and feeding. These highly evolved species have an advance and complicated nervous system. The part that allows crabs to pinch is located on the front of the crab's body. This part is known as the claw, used to catch prey. Crabs can survive in extreme conditions and can adapt to climate change very quickly. They have a pair of compound eyes that allows them to see fairly well, a sense of smell and taste that is very advanced. This helps them find food and mate easily. Crabs have soft inner body and hard exterior.

How Do Crabs Reproduce?
Crabs have a complex mating ritual and communication technique. They use their pincers for drumming or waving, a form of communication. The abdomen of a crab is just like a tail. It is folded up tightly under the body to form an abdominal flap. The sex of a crab can be easily made out by turning it over. The male crab will have a triangular flap, while the females have a broad oval-shaped abdominal flap. During mating, the crabs assume the double position, and the male carries the female. The mating can go on up to three hours and the crabs may remain in the same position for three days after mating. The female crab stores the male sperms on the underside of her abdomen till the eggs are ready to be fertilized. The sperms flow over the eggs and fertilize them. The female crab carries these fertilized eggs in a spongy mass. This spongy mass is present between the abdominal flap and the body. She uses her small legs called pleopods to cement the eggs, which forms a 'berried' appearance.

The female crab continuously waves water over the pleopods to keep her eggs healthy. She may migrate to more salty waters after mating. The eggs are incubated for about two weeks, after which the crab larvae hatch. These larvae are released into the ocean and are left to fend for themselves. The crab larvae will continue to grow for the next 4 days and become adult crabs. The crab larvae undergo many molting stages in the process of developing into an adult crab.

Interesting Crab Facts
There are many interesting facts about crabs you will enjoy reading. The following facts covers some of these interesting tit-bits about these creatures.
  • The name decapod means 10 legs and Callinectes sapidus means 'beautiful swimmer'.
  • An average crab can live up to 3 years.
  • The swim paddle is used by the crabs to swim.
  • If a crab pinches a person, the claw brakes of and soon they are able to grow a new claw!
  • Crabs are also arthropods, that is, they have segmented appendages. These appendages are similar to those in butterflies and cockroaches.
  • The thorax and abdomen of crabs is fused, known as cephalothoraxes.
  • The female crabs have broader abdomens, whereas males have narrower abdomens.
  • The shell of the crabs forms its skeleton. A crab sheds its shell and can grow a new one.
  • Crabs can be pea-sized or may grow up to 4 meters in size.
  • The Japanese Spider Crab has a walking leg span of 3 to 4 meters and 8 meters when outstretched.
  • Hermit crabs, King crabs, Horseshoe crabs and Porcelain crabs are not known as true crabs as they do not have 10 legs.
  • The Fiddler crabs have one large claw on one side. The crab raises it in action, that looks as if a person is waving.
  • The Sally Lightfoot Crab takes the title of the most colorful crab in the world as it is found in red, orange, yellow and white colors.
  • The largest crab till date was a male crab that was measured 9 inches and found in Maryland.
  • The smallest species is the Pea crab and the largest species is the giant Japanese spider crab.
This was all about crab diet, life cycle and diet. I hope this has answered your question, what do crabs eat? So the next time you savor a crab soup, crab salad, crab curry or eating it plain, you won't have to wonder about their favorite food.