Characteristics of crustaceans

What are crustaceans like?

What are crustaceans?

Shamefaced crab
Photo of crustacean. Shamefaced crab (Calappa granulata)

Crustaceans are a group of arthropod invertebrates, that is, they have articulated body and legs. These animals are characterized by having the body protected by a hard exoskeleton of chitin and mineral salts. Crustaceans are arthropods with a thicker shell.

They have 2 pairs of antennae and 1 pair of jaws.

Depending on the number of legs, they can be decapods, when they have 5 pairs of legs, such as prawns or crabs, or isopods, with numerous similar legs, such as woodlice.

They are mainly aquatic invertebrates, although we can find certain terrestrial species, such as woodlice.

General characteristics of crustaceans

Crustacean body

The body of crustaceans is divided into 2 regions: cephalothorax and abdomen. Cephalothorax is the result of the fusion of the head and thorax.

On the head, there are a pair of moving eyes, a pair of antennae and a pair of jaws.

The abdomen consists of different articulated segments.

The legs, located on the thorax, are known as pereiopods and those located on the abdomen are pleopods.

Crustacean way of life

spider crab
Spider crab (Maja crispata)

Some species of crustaceans are filter feeders and feed on microorganisms and organic detritus that are suspended in the water. Other species are carnivorous and feed on animals and decaying corpses.

Crustaceans are aquatic animals, most of them are marine, some of them live in fresh waters. However, some crustaceans are terrestrial and live in humid places, such as woodlice. Some crabs can also live on land.

They can live on beaches, submerged plants or in open seas, in rivers or lagoons, in dead leaves or under stones.

Reproduction of crustaceans

Photo of crustacean (Galathea strigosa)

Crustaceans normally have oviparous reproduction.

Most of these animals present dioecious reproduction and external fertilization.

Curiosities about crustaceans

Water fleas, with less than 1 cm in length, is a microscopic crustacean, while the largest crustaceans are Japanese spider crabs, with a length of more than 3 meters.

Crabs, lobsters, spider crabs or prawns are crustaceans, although other much stranger aquatic invertebrates are also crustaceans, like water fleas or barnacles. The moisture scale is a terrestrial crustacean.

Despite being called horseshoe crabs, they are not actually crustaceans, but rather another type of arthropods that are related to spiders and scorpions.

Summary table of the characteristics of crustaceans

In addition to having a hard shell, crustaceans are essentially characterized by:

  • Body divided into 2 parts: cephalothorax and abdomen
  • Animals with 5 pairs of legs or more, 2 pairs of antennae and 1 pair of jaws.
  • Oviparous, dioecious reproduction (they are not hermaphrodites) and external fertilization.
  • Carnivorous or filtering species (they feed on microorganisms and detritus suspended in water).
  • Primarily aquatic animals.

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Written by Editorial Botanical-online team in charge of content writing

3 December, 2020

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