In this lesson, we will explore the external parts of a crab and learn about the different parts that make up their body.
Parts of a Crab
The body of a crab consists of two main sections: the carapace and the abdomen.
- Abdomen
- Antenna
- Carpus
- Cephalothorax
- Claw or chela
- Dactyl
- Eyes
- Merus
- Propodus
- Swimming legs
- Walking legs
Parts of a Crab with Facts
Walking Legs
Crabs have ten legs, with the first pair being modified into claws called chelipeds. The remaining eight legs are used for walking and are called walking legs. These legs are jointed and can move in different directions, allowing crabs to walk forward, backward, and sideways. The walking legs also have small spines and hairs that help the crab grip onto surfaces and climb over obstacles.
Chelipeds
The chelipeds are the first pair of legs on a crab and are modified into claws. These claws are used for various purposes, including catching food, defending against predators, and fighting between themselves. The claws are powerful and can exert a lot of force, allowing the crab to crush hard-shelled prey or defend themselves against predators.
Swimmerets
Swimmerets are small, leg-like structures located on the underside of the crab’s body. These structures are used for swimming and reproduction. In males, the first pair of swimmerets is modified into reproductive organs, while in females, the swimmerets are used to carry eggs.
Eyes
Crabs have two compound eyes located on the ends of stalks. These eyes are made up of thousands of tiny lenses that allow the crab to see in many directions at once. The eyes are particularly sensitive to movement and can detect even the slightest motion in their environment.
Antennae
Crabs have two pairs of antennae, which are also known as feelers. The first pair of antennae is used to detect chemicals in the water, such as the scent of food or a potential mate. The second pair of antennae is used for touch and is particularly sensitive to vibrations in the water.
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Last Updated on January 7, 2026
