Crabs are ubiquitous creatures, found in oceans and seas across the globe. With their hard, armor-like shells and sideways scuttling, they are one of the most recognizable marine animals. But just how many legs do crabs have? Let’s take a closer look at the anatomy of these fascinating crustaceans.
A Quick Overview of Crabs
There are over 6,700 known species of crabs, inhabiting all of the world’s oceans They are found from icy polar waters to steaming tropical seas and everywhere in between.
Crabs belong to the subphylum Crustacea and the order Decapoda, which literally means “10 legs.” They are closely related to other decapods like lobsters, shrimp, and crayfish.
Their most noticeable feature is the hard exoskeleton that covers their body This shell is made up of calcium carbonate and provides protection and support Crabs periodically molt this shell and grow a larger replacement,
So How Many Legs Does a Crab Have?
As members of the Decapoda order, crabs have 10 total legs. The legs are arranged with 5 pairs on each side of their body.
However, not all 10 of the legs are used for walking. The frontmost pair is modified into large, powerful pincers known as chelae or claws. The claws are used for defense, capturing prey, and signaling to other crabs.
That leaves 4 pairs of legs, 8 in total, that crabs use for locomotion. These 8 walking legs give crabs their characteristic sideways scuttling movement.
Taking a Closer Look at Crab Legs and Claws
The 8 walking legs of crabs are slender, jointed, and taper to a point, usually ending in a small claw or pincer. They are covered in small Velcro-like hairs that help crabs grip surfaces as they move.
Crabs can regenerate lost legs through successive molts. If a leg is severed at a joint, it may grow back more quickly. Leg regeneration is vital to a crab’s survival.
The frontmost pair of legs that form the claws or chelae are thicker and more robust than the walking legs. The claws are covered in small spines for traction and leverage.
One claw is usually slightly larger than the other. Crabs use their larger crusher claw to defend themselves and crack open hard-shelled prey like clams or oysters. The smaller pincer claw is more dexterous and used to manipulate food.
Variations in Crab Legs
While most crabs conform to the standard model of 2 claws and 8 walking legs, there are some variations:
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Spider crabs: Have legs that can span 12 feet tip-to-tip. Their legs help them blend into seaweed and kelp.
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Fiddler crabs: Males have one massively enlarged claw used for signaling and defense. Females have two normal-sized claws.
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Hermit crabs: Lack a complete hardened shell, so they live inside discarded seashells for protection. They have 4 pairs of walking legs and no large claws.
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Porcelain crabs: Have only 8 legs total. They have lost the front pair of walking legs and just retain the claws and 3 remaining pairs.
How Crabs Use Their Specialized Legs and Claws
Crabs are adapted to make the most of their unique anatomy:
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Sideways movement: The articulation of their legs favors lateral movement for quick escapes.
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Leverage: The jointed legs provide leverage for prying open shellfish or cracking seeds and nuts.
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Gripping: Velcro-like hairs allow them to grip rocks, coral, and other surfaces.
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Defense and offense: The large crusher claw deters predators and captures active prey like fish.
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Burrowing: Certain crabs use legs and claws to dig burrows for protection.
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Signaling: Male fiddler crabs wave their giant claw to attract females and deter rivals.
Importance of Leg Design for Survival
The specialized leg design of crabs is key to their evolutionary success and survival in the marine environment:
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Allows them to navigate through rocks and reefs.
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Provides defense against predators.
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Enables efficient capture of prey.
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Permits fast escape reactions like the sideways scuttle.
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Offers a platform to balance the weight of their shells.
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Gives purchase and leverage for prying open hard shells.
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Allows signaling and display in mating competitions.
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Aids in establishing territories and building shelters.
Crabs belong to the aptly named Decapoda order, sporting 10 total legs. But only 8 of these legs are used for walking, while the front pair forms their iconic pincers or claws. This adaptable body plan has served crabs extremely well, allowing them to thrive in the challenging conditions of marine environments across the globe. The next time you spot a crab sidling across the beach, take a moment to appreciate the ingenuity of its anatomy!
Color, Size, and Counts
There are three types of Alaskan king crab and each is defined by its exterior color. Red king crab (paralithodes camtschaticus), considered the most popular and prized king crab for consumption around the world, has a dark reddish brown shell. They are most abundant off the shores of Alaska.Blue king crab (paralithodes platypus), with a visibly blue toned shell, live for the most part in the North Pacific Ocean. Blue king crab legs are slender and more oval shaped compared to red king crab legs. Golden king crab (lithodes aequispinus), has a dark brown shell. The smallest of the three, they weigh an average 5-8 pounds from tip to tip. They’re found from British Columbia to the Aleutian Islands and Japan (http://www.adfg.alaska.gov/).
The average weight of a king crab is 6 to 10 pounds, but some king crab can grow to more than 20 pounds with a leg span of 6 feet across. Though many of those king crabs close to 20 pounds were caught in the early 80s prior to the crash of the Bristol Bay fishery. In order to increase in size, king crabs must “molt” their shell. Juvenile king crabs molt frequently the first years of life and mold less when they reach 4-5 years of age. King crab is measured by the number of king crab legs it takes to reach 10 lbs of crab meat. A size of 6-9 would translate into “6-9 crab legs add up to 10 pounds.” Only king crab legs make up the count as claws are excluded.
The anatomy of King crab consists of shoulders, merus, legs, claws, joints, tips, spines and a carapace (or body). Unlike other crabs, king crabs have only six versus eight legs, and two claws. The body, or carapace, section of king crabs is typically sent to canners while the legs are separated and served individually.
The most preferred meat from a king crab is in the legs. Most king crab enthusiasts state that the best section is the merus section, that is, the largest section of the crab leg. Compared to other crabs, the king crab claws are not as notorious as the legs. Red king crab is regarded as the premium of king crab because its meat is the moistest and sweet. If your crab meat is bluish in color, that indicates either that the crab was under-cooked or wasnt cleaned appropriately. If it’s excessively salty, that’s a sign that the cooked crab wasn’t chilled properly prior to brine freezing.
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Beautiful Science – The Science of Crabs
FAQ
Do king crabs have 10 legs?
The king crab is one of the largest edible crabs, and its anatomy is similar to that of other crabs, except that it has six walking legs instead of eight. Its claws are also distinct in shape: the larger claw is used for crushing prey, while the smaller claw handles food delicately.
Do crabs have four legs?
Crab facts
Crabs are decapods (ten-footed, though crabs usually have four pair of legs and one pair of claws) from the crustacean family. They generally walk and swim sideways. Crabs are omnivorous, eating both plants and animals.
Which crab has 10 legs?
Both lobsters and crabs are known as decapod crustaceans, which means they have 10 legs. They are invertebrates that are actually closer in relation to arachnids and insects, as opposed to fish.
How many legs does an Alaska crab have?
Each crab has eight king crab legs and two claws, with one of the claws being significantly larger than the other. Only six of the king crab legs are sold or have any commercial use, with the back two legs being very small.
How many legs does a crab have?
Crabs are crustaceans with 10 legs. However, they are often seen with only 8 legs because two of their legs are modified into claws. So, how many legs do crabs have? The answer is 10. A crab on water. Image by David Mark from Pixabay What Are Crab Claws For? Crab claws are used for defense and offense.
Do all crabs have claws?
No, not all crabs have claws. There are some species of crabs that don’t have claws at all. Instead, they have long, thin legs that they use to catch prey. Several species exhibit claws of different sizes. If playback doesn’t begin shortly, try restarting your device. An error occurred while retrieving sharing information. Please try again later.
What is the anatomy of a crab?
The typical anatomy of a crab includes a hard exoskeleton, a pair of claws, and multiple legs. Crabs belong to the order Decapoda, which also includes lobsters, shrimp, and crayfish. They have a broad, flat body, and their legs are arranged in a specific pattern. The legs of a crab are used for walking, swimming, and sensing their environment.
How many legs does a king crab have?
A size of 6-9 would translate into “6-9 crab legs add up to 10 pounds. ” Only king crab legs make up the count as claws are excluded. The King crab has a merus (shoulders), legs, claws, joints, tips, spines, and a carapace (or body). Unlike other crabs, king crabs have only six versus eight legs, and two claws.
How many legs does a false crab have?
False crabs: these resemble true crabs but belong to different groups. Some false crab species, like porcelain crabs, have fewer than 10 legs, with some having only eight. Ever heard of a crab that cracks coconuts with its claws?
What is the difference between crab claws and legs?
The walking legs, on the other hand, are longer and more slender than the claws and are made up of a series of joints that allow them to be moved in a variety of different ways. Overall, the difference between a crab’s claws and legs is one of the key characteristics that distinguishes them from other types of crustaceans.