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7 Characteristics of Crabs (Pictures & Facts)

Some species of crab can grow to be very large, while others are only a few inches long. Crabs are very important in the aquatic food chain. They are unique among shellfish, and they have some amazing adaptations that allow them to survive in their underwater homes. Read this list to learn more about these 7 characteristics of crabs.

What is a Characteristic?

A characteristic is a feature of animals that is obviously present, such as eye color, nose shape, or skin pigmentation. Traits are the different ways characteristics can present, such as green eyes, blue eyes, or brown eyes.

At times, a population will experience an adaptation of a trait when one trait, such as brown eyes, evolves to be the dominant trait in the population. This essentially stops any other trait from being displayed in the population. Adaptations arise over the course of generations to support the survival of a population.

7 Characteristics of Crabs

Crabs are a type of crustacean that live in both fresh and saltwater environments. They have a hard exoskeleton that protects their body, and they use their large claws for catching food and for defense. Here are 7 characteristics of crabs that make them unique in the animal kingdom.

1. Short Tails

red king crab
Red king crab | Image by David Mark from Pixabay

While most animals have long tails that they use for balance and movement, crabs have very short tails that don’t seem to serve any purpose. However, these tails are actually essential for the crab’s survival.

The short tail of a crab allows it to move quickly and easily in the water, which is important for escape from predators. Additionally, the tail helps the crab maneuver in tight spaces and navigate through narrow crevices. This is an important characteristic because it allows crabs to find food and shelter in areas that other animals cannot reach.

2. Five Pairs of Legs

Crabs have a pair of legs on each side of their body. This gives them a total of 10 legs. The legs are used for walking and climbing.

They help the crab to move around and find food. The legs also help the crab to escape from predators.

The first pair of legs is called the chelipeds. These legs are used for catching food and for fighting and have pincers on the front of them. The other four pairs of legs are used for walking.

The legs of a crab are covered in hair. This helps the crab to move around and grip surfaces. It also helps to protect the crab from predators. The legs are also very strong and can be used to break open shells.

3. Pincers

Crab in sea shore

Crab pincers, also called chelae, are a crab’s most recognizable feature. These large claws are used for defense, catching prey, and communication. Each claw has two major parts: the immovable finger and the movable dactylus.

The size and shape of crab pincers vary depending on the species of crab. For example, fiddler crabs have much smaller pincers than blue crabs. The size of a crab’s pincers also depends on its gender; male crabs usually have larger claws than females.

The immovable finger is the part of the claw that is attached to the crab’s body. This finger is relatively thick and strong, and it can not be moved.

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The movable finger, on the other hand, is thinner and more flexible. This finger can be opened and closed, allowing the crab to grasp things with its pincers.

The inside of a crab’s pincer is lined with sharp teeth. These teeth are used to help the crab catch and eat its food.

4. Hard Exoskeleton

Crabs have a hard exoskeleton that protects them from predators and the environment. The exoskeleton is made of chitin, which is a tough, flexible material. Crabs can grow new exoskeletons as they molt, or shed their old ones.

5. Carapace

Fiddler Crab
Fiddler Crab Sheila Shafer-Roberson from Pixabay

The carapace is the hard, outer shell of a crab. It is made up of two plates that are hinged along the crab’s back. The carapace is part of the crab’s exoskeleton, which is the hard, outer skeleton that protects the crab’s internal organs and gills.

A crab’s carapace protects its internal organs and gills from predators and other threats. The carapace also helps the crab to regulate its body temperature and to stay hydrated.

6. Gills

Crabs have gills that extract oxygen from the water and circulate it throughout their body. These gills are located on the sides of the crab’s body and are covered by thin, delicate filaments. The filaments are constantly in motion, allowing water to flow over them and providing a large surface area for gas exchange.

7. Multi-Colored Shell

Fiddler crab
Fiddler crab

Crab shells come in a variety of colors depending on the species. The most common colors are red, blue, and brown. However, some species can have shells that are yellow, orange, or even white.

The habitat of a crab influences the color of the shell greatly. For example, crabs that live in the ocean tend to have darker shells so that they can blend in with the darkness of the water.

Crabs that live on land typically have lighter-colored shells. This is because lighter colors help to reflect the light and keep the crab cooler in warmer climates.

The coloring of a crab’s shell is also intended to camouflage the crab from predators. The colors help the crab to blend in with its surroundings and make it more difficult for predators to spot them. This is especially important for baby crabs, who are more vulnerable to being eaten.

The color of a crab’s shell can also be affected by the food that the crab eats. For instance, crabs that eat a lot of algae tend to have green shells.

The coloring on a crab’s shell is not just for looks. The colors can also help to indicate the crab’s health. For example, a healthy crab typically has bright and vibrant colors on its shell.

However, a crab that is not feeling well may have duller colors. The coloring on a crab’s shell can also change over time. For example, a young crab typically has a brighter-colored shell than an older crab. As the crab ages, its shell will start to fade and become duller in color.