Crabs have many different parts, but only some are edible. It is important to know how they are put together so you can decide which parts to break into and which ones to use as a stock base.
Crabs are delicious crustaceans that many people love to eat. Their meat is sweet, moist, and flaky. However, you may have wondered when eating crab – do they have bones like fish? The answer is no, crabs do not contain true bones. Instead, they have a hard exoskeleton that protects their body.
In this article, we’ll explore the unique anatomy of a crab and learn exactly why they don’t have an internal skeleton like we do Read on to find out more!
Crabs Have an Exoskeleton Instead of Bones
Crabs, along with lobsters, shrimp, and other crustaceans, are part of a group called arthropods. The key feature of arthropods is having an exoskeleton rather than an internal endoskeleton made of bone.
An exoskeleton is a rigid outer covering that encases and protects the crab’s body. It is made up of a complex material called chitin which is also found in the cell walls of fungi and the shells of insects.
Chitin is a tough, fibrous substance that works like an armor suit. It can withstand physical impacts and pressures from the crab’s environment.
The exoskeleton completely encloses all of the crab’s organs, muscles, and tissues. It also provides anchoring points for their muscle attachment.
Advantages of an Exoskeleton
Having an exoskeleton gives crabs several key advantages:
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Protection – The hard shell acts as armor to shield from predators and physical damage.
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Support – It provides structural support and maintains the crab’s shape.
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Waterproofing – The shell prevents drying out and functions like a waterproof wetsuit.
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** Attachment** – Muscles can firmly anchor onto the interior of the shell.
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Calcium Storage – Calcium from the exoskeleton can be reabsorbed and used for other biological processes.
Disadvantages of an Exoskeleton
However, there are some downsides to having an exoskeleton instead of an internal skeleton:
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Growth Limitations – Crabs must periodically molt or shed their rigid exoskeleton to allow for growth. This makes them vulnerable until their new shell hardens.
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Damage Risk – Cracks or fractures in the shell threaten the crab’s survival since it cannot heal itself.
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Energy Cost – Producing and maintaining the exoskeleton requires a substantial amount of metabolic energy.
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Limited Flexibility – An exoskeleton restricts range of motion compared to an endoskeleton.
Parts of the Crab Exoskeleton
Now let’s take a tour of the crab exoskeleton by looking at its main parts and sections:
Carapace
This rounded, plate-like structure covers the top side of the crab. It protects the head, stomach, intestines, and other vital organs. The eyes and antennae poke out the front of the carapace.
Pincers
The front legs end in a pair of large, powerful pincers or claws used for defense, hunting, and manipulation of food. The claws are lined with sharp cutting edges.
Walking Legs
Crabs have a total of 10 legs including the pincers. The remaining 8 walking legs provide mobility and are strong enough to support the weight of the crab.
Abdominal Flap
On the underside is a fold of the exoskeleton called the abdominal flap. Under here are the reproductive organs as well as tiny appendages called swimmerets which aid breathing.
Tail
The tail section contains the anus and is folded under the body for protection. This is the only uncalcified part of the exoskeleton.
Internal Anatomy of a Crab
On the inside, crabs contain a much softer anatomy including:
- Brain and nerve tissues
- Sensory organs – eyes on stalks and antennae
- Stomach, digestive system, and hepatopancreas (liver)
- Gills for breathing
- Heart and open circulatory system
- Reproductive system – testes or ovaries
- Muscles that attach to the inner walls of the exoskeleton
The next time you enjoy some delicious king crab legs, Dungeness crab cakes, or cioppino stew, keep in mind those meaty morsels came from inside a living suit of armor!
Why Do Crabs Molt Their Exoskeleton?
In order for crabs to grow, they must shed their rigid exoskeleton periodically in a process called molting or ecdysis. This is necessary because their tough outer shell has no ability to expand.
Here’s an overview of how crabs molt:
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A new soft exoskeleton forms under the hard outer shell.
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The crab stops eating and secretes enzymes to loosen the interior shell.
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It backs out of the old shell which splits at the seams.
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For a few days, the crab rapidly absorbs water to expand its new soft shell.
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Hardening of the new shell through calcification takes 1-2 weeks.
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Growth between molts is 15-20% increase in size.
Young juvenile crabs may molt several times a year, while full grown crabs only molt once annually. They are vulnerable during molting until their new shell fully hardens.
Eating Crab Without Any Bones
One of the best parts about eating crabs is that there are no bones to worry about! The meat comes entirely from the muscle inside the exoskeleton. Here are some tips for enjoying crab:
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Use shell crackers and pickers to open legs, claws, and the body.
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Carefully break apart shell sections to extract whole chunks of meat.
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Pick out any remaining shell fragments or cartilage.
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Enjoy crab on its own or use it in seafood recipes like pasta, salad, or dip.
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For a splurge, try the prized meat from king crab, snow crab, or Dungeness.
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Opt for canned crab meat for quick sandwiches or crab cakes with no work.
So relish your crab feast without fear of a fishbone getting stuck! The edible parts are 100% exoskeleton-free.
Crab Skeletons as Collectibles and Decor
The inedible shells leftover from cooked crabs can have an artistic second life. Their complex architecture makes them fascinating objects to display and collect.
Some ideas include:
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Arranging them as-is for decor on shelves
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Spray painting them in bright colors and gluing as ornaments
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Using small shells and claws to make jewelry pieces
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Gluing legs onto a base to form sculptures or potted plant toppers
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Filling large shells with soil and succulents to create planters
Let your imagination run wild with how to transform crab skeletons into art and home decor!
Comparing Crabs and Lobsters
Crabs and lobsters have similar anatomies – both being crustaceans with an exoskeleton. But there are some key differences:
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Shape – Crabs have a wider body, whereas lobsters are longer and tubular.
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Legs – Lobsters have large front claws like crabs, but four additional pairs of thinner, spindly legs.
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Habitat – Crabs live on the sea floor, while lobsters usually inhabit rocky crevices.
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Meat – Lobster tail meat is firmer and often considered more premium.
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Price – Lobsters are pricier than many crab varieties due to higher demand.
No matter which you choose, keep in mind crustaceans have zero bones so you can eat every bit!
Fascinating Facts About Crabs
Here are some interesting tidbits about these unique marine animals:
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There are over 4500 crab species adapting to diverse ocean habitats worldwide.
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Some king crabs have leg spans up to 12 feet tip to tip!
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Fiddler crab males have one giant claw they use to signal females and fight rivals.
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Migrating red crabs on Christmas Island form a red tide of millions moving to the sea to breed.
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Crabs walk sideways by using diagonal motions of their legs rather than moving directly from side-to-side.
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Most commercially fished crabs are caught using either crab pots or trawl nets.
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Crabs communicate by drumming or waving their pincers to produce a series of clicks and snaps.
Crabs captivate us with their quirky sideways scuttle, bulky proportions, and armored shells. We often take for granted their unique anatomy which allows them to thrive beneath the waves. Next time
The Anatomy of a King Crab
The king crab is one of the largest edible crabs. Their anatomy is similar to other crabs, except that they have six walking legs instead of eight. Their claws are also two different shapes. The larger claw does the heavy lifting, like crushing prey. The smaller claw is for more delicate handling of food. You can also easily tell the difference between their genders. A male king crab has a narrow abdomen flap, while a female has a wide flap.
Three main types of king crab are available on the market— each is distinct in its outward appearance:
- The red king crab is the most sought-after crab in the world. Its shell is a reddish brown color. Red king crabs occur in British Columbia, Japan and Alaska. A lot of them can be found in Bristol Bay and the Kodiak Archipelago in Alaska. They live between the tidal zone and at least 100 fathoms deep. They can get as big as 24 pounds and have legs that are 5 feet long.
- Blue king crab: This crab’s shell is blue, as its name suggests. Red king crab legs are longer and rounder than this crab’s.
- Golden king crab: This type of crab is the smallest and has the least amount of meat. It has a golden-orange shell and weighs 5 to 8 pounds.
- Jonah crab: This crab is oval-shaped and has a red top and a yellow bottom. Jonah crabs’ legs may also have spots of red and yellow on them. Most of the time, you can find them off the coast of North America, from Newfoundland to Florida.
How Many Legs Do Crabs Have?
Most crabs have 10 legs: four pairs of walking legs and one pair of pincers. However, the number of legs varies from species to species. Some crabs, such as the porcelain crab, have eight legs.
Do Crabs Have Bones?
FAQ
Does crab meat have bones?
Is a crab shell a skeleton?
Do crabs have a heart?
Do crabs have a backbone?
This exoskeleton offers structural support and protection, allowing crabs to navigate their environments effectively. Despite the absence of a backbone, crabs possess well-developed nervous systems, enabling them to perceive their surroundings, make informed decisions, and react efficiently to stimuli.
Are coconut crabs healthy to eat?
Crabs are rich in omega 3 fatty acids, protein, vitamins like riboflavin and minerals like selenium, copper, phosphorus. Coconut crabs are not known to be poisonous. The fat in the abdomen and the egg inside the female are the delicious edible parts. It is prepared by steaming or boiling them in coconut milk. Consuming coconut crab along with sea mango, cerbera manghas may make the coconut crab toxic due to the presence of cardiac cardenolides(cardiac active steroids). This causes electrolyte imbalance that affects the electrical conductivity of the heart.
What are the body parts of a crab?
The cephalothorax contains the crab’s eyes, antennae, mouthparts, and legs. The abdomen, on the other hand, is the soft, fleshy part of the crab’s body that contains its internal organs. Additionally, crabs have two large claws, also called chelae, that are used for defense and capturing prey. How do the body parts of a crab function?
Do crabs have teeth?
Crabs have teeth in their stomachs, which they use to grind up their food before it is passed on to their digestive system. The teeth are made up of chitin, the same material that makes up their exoskeleton. Crabs are fascinating creatures with a wide range of behaviors.