How Many Legs Do Crabs Have? Clawless Facts You May Not Know

Abhijeet Modi
Feb 29, 2024 By Abhijeet Modi
Originally Published on Nov 04, 2021
Horned ghost crab on the Maldives beach.
Age: 3-18
Read time: 6.3 Min

Crabs come under the classification of crustaceans of the infraorder Brachyura, together with crayfish and all different marine insects, making up the largest group of arthropods.

Infraorder is basically a taxonomic category. All crustaceans are members of the phylum called Arthropoda, which has the highest number of members on Earth; it covers almost 75% of all living things in the world.

Crabs live in all types of water bodies like oceans and freshwaters and are even found on land. Despite this diversity, crabs have some functions and features that distinguish them from other comparable creatures.

Crabs were first found several million years ago. They are found in almost all types of marine environments. There are over 6,793 species of crab found throughout the world in the oceans, in clean water, and even on land.

They also move in the form of a group in the water. Hermit crabs are mostly known to form a group while moving or when they search for food.

After reading all about the legs of crabs, do read how many legs do lobster have and how many legs do cockroaches have.

What are chelipeds?

Do the weirdly shaped legs of crabs have names of their own?

Male fiddler crabs have got big claws. These males, when encountering other crabs, greet them by waving their claws. They have compound eyes which are carried on stalks. These eyes help hermit crabs in seeing things beside and behind them. Their eyes can easily detect UV rays in low light conditions.

The principal cheliped is the limb that contains the big claw. A cheliped usually refers to the whole limb, not only the claw. Crabs use chelipeds that are big claws for protection and to seize prey. Each of the four final segments in the species incorporates a couple of walking legs. In the abdomen, the primary five segments have a couple of swimmerets, which create water currents and have a purpose in reproduction.

Hermit crabs have five pairs of legs, from which they use the second and third pairs for walking. They have a hard outer shell. A hermit crab carries this shell around, which is borrowed from seashells. They have also got a very short projecting tail.

A crab often grows and reaches maturity within 24 months. The shell these crustaceans have can't expand as the crab grows, which often leads to the shedding of the shell.

What do crab legs look like?

A crab's body is divided into three parts: the head, the thorax, and the abdomen.

The head and thorax are merged collectively below the carapace. A crab's body is blanketed with a thick exoskeleton, which is usually composed of a substance called mineralized chitin, and it is armed with two claws called chelae. These animals have claws at the end of their front pair of legs. These claws work in a similar way to pincers.

Pincers are technically a tool that has two parts and is useful for gripping things. Crabs use their pincers for fighting and for hunting and tearing flesh. If you ever get hurt by pincers, it can cause pain.

Hermit crab legs are often tailored for different purposes. The long front legs of these species have developed into pincers, technically known as chelipeds.

The remaining pair of legs of a crab grows into small swimming appendages, known as swimmerets or pleopods. King crabs can easily fold their ultimate pair of legs below their body when they are walking. These animals use those legs for the movement of sperm and even for warming growing eggs. The crab always stores sperm till eggs are fully developed. Eggs are fertilized after the female keeps them and carries them in their abdomen till they hatch.

Some crab species, like the snow crab, have shells on their legs that are breakable. They can be cracked and opened by using only your hands! Most crab species have enlarged claws either on the left or right. The most popular among them is the left-handed one, especially in a left-clawed hermit crab.

Red crab on a beautiful beach.

How many legs do crabs have?

Crabs are all contributors to the order Decapoda; this literally means these sea animals with thick shells have got ten feet.

Almost all crabs have 10 legs except a few select subcategories. Horseshoe crabs, which come under the phylum Chelicerata, have eight legs and are intently associated with spiders. Most crabs have a similarity to lobsters and crayfish. Having 10 legs is an important difference that separates crabs from centipedes of the Chilopoda class, spiders of the Araneae order, millipedes of the Diplopoda class, ticks belonging to the Acarina order, and scorpions of the Dromopoda subclass.

The 10 legs of all decapods are located in bilateral symmetry, with five on each side. However, a number of their legs are advanced in order to serve functions other than walking, like self-defense and meals acquisition, while they swim. The last four pairs are used for walking, whereas the front pair is in the shape of strong gripping claws. Crabs can creep ahead very slowly, however, they prefer to scuttle sideways due to the fact these animals with pincers move faster if they move sideways.

Do all crab species have the same legs?

True crabs, in addition to other creatures which are relatively close to them, have five pairs of legs, which is 10 legs in total.

True crabs consist of a depressed carapace. However, a number of their legs are advanced to serve various functions. Not only walking, but they are also capable of defending themselves, collecting food, and swimming via those legs.  The front pair of legs are very strong and have gripping claws which help in attacking, while the other four pairs are used for strolling.

All crabs of the Decapoda order consist of 10 legs, grouped as five pairs. This consists of the suborder Brachyura, which includes real crabs. It also includes the subphylum Anomura, which incorporates king crabs, hermit crabs, and squat lobsters. However, it's crucial to remember that horseshoe crabs aren't crabs and are more associated with spiders. These sea animals have 12 legs; thus they fall under the order Xiphosura and are generally not considered crustaceans like crabs.

Different varieties of crabs have legs that have advanced and evolved for more than one kind of function. King crabs certainly fold their legs below them when walking, and they even use their legs to transfer sperm. Fiddler crabs have various sized claws at the ends of their legs, and they use them to acquire meals and even to oppose and protect themselves during a fight.

The crab with the longest legs is the Japanese spider crab. It has a name that includes 'spider' but is actually a crab. Their legs are so long that if they're extended, then they can possibly be as long as 12 ft (3.6 m) from claw to claw. Swimming crabs, which include the flying crab, have a pair of flattened, lower back legs which they use as paddles for swimming.

What do crabs eat? Crabs eat a wide range of foods and usually use their claw to crack open the body of their prey. Crab species living in the sea eat green and red algae, decay matter, and dead shrimp and fish. These sea animals generally eat meat that is soft and luscious. They also attack sea snails and eat them, and take their soft shells.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for 'How many legs do crabs have?' then why not take a look at 'How many legs do scorpions have?' or 'Hermit crab facts'.

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Written by Abhijeet Modi

Master of Computer Science

Abhijeet Modi picture

Abhijeet ModiMaster of Computer Science

An experienced and innovative entrepreneur and creative writer, Abhijeet holds a Bachelor's and Master's degree in Computer Application from Birla Institute of Technology, Jaipur. He co-founded an e-commerce website while developing his skills in content writing, making him an expert in creating blog posts, website content, product descriptions, landing pages, and editing articles. Passionate about pushing his limits, Abhijeet brings both technical expertise and creative flair to his work.

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