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9 Characteristics of Crustaceans

Crustaceans are a large, diverse group of arthropods that include crabs, lobsters, shrimp, and barnacles. Distinct characteristics of a crustacean is their hard exoskeleton and jointed appendages. Crustaceans are found in both fresh and saltwater environments and can range in size from microscopic to over two feet long.

Crustaceans are an important food source for humans and other animals, and they also play a role in the recycling of nutrients in aquatic ecosystems. Some species of crustaceans are considered pests, while others are prized for their beauty or usefulness.

Despite their wide range of habitats and lifestyles, all crustaceans share some common characteristics. Read this list of 8 characteristics of crustaceans to learn more about them.

What Is A Characteristic?

A characteristic is a definitive feature of an animal. A good example is eye color in humans. All humans have some type of eye color. A trait is the eye color you have- for example, blue eyes, green eyes, or brown eyes.

Adaptations occur when a population evolves over several generations to make one trait dominant in the gene pool. For example, brown eyes become dominant in a population to the point that they are the only eye color because they make predation less likely.

9 Characteristics of Crustaceans

1. Hard Exoskeleton

Crabs
Crab | Image by WikiImages from Pixabay

Crustaceans are a very successful group of animals, in large part due to their hard exoskeleton. This tough outer shell provides protection from predators and the environment and also helps the animal to stay properly hydrated. The exoskeleton also allows crustaceans to move freely in water, which has helped them to spread to all corners of the globe.

Crustaceans are incredibly diverse and can be found in a wide variety of habitats. Some species are specialized for life in deep-sea vents, while others make their homes in freshwater lakes and rivers.

No matter where they live, though, all crustaceans share the common trait of having a hard exoskeleton. This simple characteristic has allowed these animals to thrive in a wide range of environments and become one of the most successful groups of animals on Earth.

2. Jointed Appendages

Jointed appendages allow crustaceans to move freely and efficiently in their watery habitats. They also enable crustaceans to capture and process food, as well as to defend themselves from predators.

3. Antennae

Mantis shrimp
Mantis shrimp | image by prilfish via Flickr | CC BY 2.0

The long, slender antennae of crustaceans are among their most conspicuous and important features. These appendages are used for sensing the environment, locomotion, and for feeding. In addition, the antennae play an important role in communication, both within the species and with other animals.

The antennules, or first antennae, are the most delicate and sensitive of the crustacean’s antennae. They are used primarily for touch and taste, and they are also very important in helping the animal orient itself. The second pair of antennae, the antennal feelers, are much longer and more robust than the antennules.

4. Tails and Claws

Many species of crustaceans have a tail that helps them to swim. The tails of some crabs and lobsters are also used as weapons. The large pincers on the claws of some crustaceans are also used for defense and for catching prey.

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5. Carapace

Lobster’s head
Lobster’s head | image by Andrew Wilkinson via Flickr | CC BY-SA 2.0

The carapace is a hard, protective shell that covers the head and thorax of many crustaceans as part of the exoskeleton. The carapace provides protection from predators and from the environment. It also helps to support and protect the delicate gills that are used for breathing.

Some crustaceans, such as crabs and lobsters, have a very hard exoskeleton. This provides them with additional protection from predators and the environment. The hard exoskeleton also makes it difficult for these animals to move, so they are often found hiding in crevices or under rocks.

6. Biramous Appendages

Biramous appendages are a defining feature of crustaceans. These appendages have two branches, or rami, that extend from a common point. The outer branch is called the exopodite, while the inner branch is called the endopodite.

The exopodite is typically longer than the endopodite and bears most of the appendage’s bristles. The endopodite is usually shorter than the exopodite and bears a claw or other type of terminal structure. The biramous nature of crustacean appendages provides them with greater flexibility and dexterity than their uniramous counterparts.

Crustaceans use their biramous appendages for a variety of purposes, including locomotion, feeding, and sensing the environment. The appendages are also used in communication, both within the species and with other animals.

7. Segmented Body

American Lobster
American Lobster | image by Derek Keats via Flickr | CC BY 2.0

Most crustaceans have a segmented body, which means their bodies are divided into sections, namely the head, thorax, and abdomen. The number of segments can vary depending on the species, but most crustaceans have at least two pairs of jointed legs. Some crustaceans have a cephalothorax, where their head and thorax are fused rather than segmented.

8. Gills

Crustaceans breathe using gills, which are located on the sides of their bodies. The gills are covered with tiny hairs that trap oxygen from the water and allow it to enter the crustacean’s bloodstream.

In order for the gills to work properly, they must be kept moist. This is why you often see crustaceans moving their bodies back and forth in the water. They are trying to keep their gills from drying out.

9. Compound Eyes

Crab crawling on rocks
Crab crawling on rocks | image by Rivindu Weerasekera via Flickr | CC BY-SA 2.0

Crustaceans have a pair of compound eyes on each side of their head. Each eye is made up of many small eye units, called ommatidia.

The ommatidia are arranged in a curved row, with the widest part of the curve towards the back of the eye. This arrangement allows the crustacean to see in all directions at once.

The compound eyes of a crustacean are very sensitive to light. They can detect even the slightest changes in light intensity, which helps the crustaceans to avoid predators and find food. The compound eyes also have a very wide field of view, which allows the crustacean to see its surroundings clearly.