10 Interesting Facts About Pet Crabs That You Should Know

Facts About Pet Crabs

Ever consider having crabs as pet? They can be fun little creature for your aquarium. They come in different sizes, colors and patterns. There are many types of pet crabs that you can choose from include rainbow land crabs, red claw crabs, gold claw crabs, fiddler crabs, panther crabs, land hermit crabs, pom pom crabs, vampire crab.

In order to understand more about them, here are 10 interesting facts about pet crabs that you should know.

Do crabs have brains?

Crab has a tiny brain that process sensory inputs from its eyes. The ventral ganglion provides nerves to crabs’ walking leg and sensory organs.

It has a different nervous system from that of mammals, birds or fishes. It has dorsal ganglion and a ventral ganglion, connected by a circumesophageal ganglion.

Its dorsal brain locates between the eyes and the anterior end. While the ventral ganglion is between its legs, beneath the internal organs.

Crab’s brain is tinier than many small animals. If compare neuronal count, crab brain is about 10 time smaller than a bee’s brain. But it has the cognitive capacity for complex learning.

Do crabs feel pain?

Yes, crabs can detect, feel and react to pain. They have good senses of sight, smell and taste.

Researchers have found out that crabs not only feel pain but also can hold a memory about it (Science Daily)

We need more studies to know for sure how crab or other crustaceans feel pain. But it is important that we care more and more about them.

Do crabs pee out of their eyes?

crab as a pet

Crab’s urine release area is at the base of the antennules. That is where they urinate from.

You can hardly notice that as crabs secrete a very small amount each time.

Crabs excrete its solid waste from an anus at the end of the abdomen inside the shell. Then, they use the small rearmost legs to move it out of their shells.

Why can’t crabs walk forward?

Crabs do not walk forward because their body are born to move sideways. They have multiple legs on the side of their body. Those legs, with the leg joints bend outward move fast and efficiently sideways. 

Crab’s flat body and its flexible legs make it easy for them to squeeze into narrow space or bury under the sand.

Do crabs have blood?

Crabs do have blood. It is just that their blood is different from human and animals. Instead of iron, it uses copper to carry the oxygen.

Horseshoe-crab blood has a distinct blue color. That comes from hemocyanin – the metal copper in their oxygen-transporting proteins.

Their blood is in high demand with a hefty price tag. It is due to the fact that it contains a clotting agent, important in medical field to make LAL – Limulus Amebocyte Lysate.

LAL is a concoction that helps with identifying bacterial contamination for medical devices, and even vaccines. In addition, horseshoe crab blood has a vital amebocyte. It is used in FDA testing.

This amazing blue blood is important in biomedical industry and the lysate comes from it worth $60,000 per gallon.

What types of crabs can live with fish?

Most freshwater crabs can live with other fishes and crustaceans. However, you need to avoid putting aggressive fishes in the same tank with your crabs.

If you have fiddler crabs, they are not suitable to live with fish. They can catch and eat the fish.

How do crabs give birth?

After mating, female crabs store sperm and can retain it for a year or longer. Until the eggs are fully developed and once fertilized, female crabs carry eggs in her abdomen. It has small appendages where the eggs attach till hatching.

One to two weeks later, crab eggs turn into zoea larvae. Crabs released these newly hatched, transparent zoea larvae into the water like plankton.

Zoea has jointed limbs, a crusted external skin and segmented tails. They grow through different stage and then transform into the crab that we are familiar with.   

Depend on the species, crabs lay between 50,000 to 8 million eggs in a mating session. But only a very small number of egg can survive to become an adult crab.

What are crabs favorite food?

Crabs are carnivore. They like to eat fish, squid, snail, worm. Some crab species eats fish eggs and even small crabs.

They are not picky eaters. Crabs can use their claws skillfully to break open mussels, clam shells to eat the flesh and innards inside.

Apart from seafood, crabs also eat plants and algae. Hermit crabs eat fruits, nuts, cereals as well.

How long can a crab live?

Crabs can live between 1 to 70 years. Crab’s life expectancy depends on various factors including species, environment, habitat. 

Look at the life expectancy of different crab species below:

  • Pom pom crab: around 1 year
  • Fiddler crab: 1 to 1.5 years
  • Female blue crab: 1 to 2 years. Male blue crab can live longer, up to 3 years. Though not common, some blue crabs can live up to 8 years.
  • Gold claw crab: up to 2 years
  • Rainbow land crab: 2 to 3 years
  • Panther crab: 2 to 3 years
  • Vampire crab: up to 3 years
  • The Dungeness crab: up to 10 years
  • Horseshoe crab: 20 years
  • King crab: 30 years
  • Hermit crab: 30 years and beyond. Coenobita brevimanus, one species of terrestrial hermit crab can live up to 70 years.

Crabs’ life span in the wild and as pets are different. Most crabs live much longer in its natural habitats. For example, hermit crabs can live for more than 30 years in the wild. But as pet, they can only live for 1 to 12 years depend on how well their owners take care of them.


Just like any other pets in the pet world. In order to take care your pets well, you need to understand them well.

Each crab has its own preferred habitat, diet and proper care requirements. But most are easy to look after and they are great pets for your home. It is important that you know how many crabs you want to take care of and have the space for them. As some crabs like to live by themselves, while some prefer to live in pairs or in groups.

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