Crustaceans are a fascinating and diverse group of animals commonly found in oceans, rivers, and other aquatic environments. In this article, you will learn what crustaceans are, explore a clear and accurate list of common crustaceans, and discover interesting facts about some well-known species. This guide is designed to help English learners build vocabulary while learning correct biological information.
Contents
What Are Crustaceans?
Crustaceans are a group of animals that belong to the arthropod phylum. Most crustaceans live in marine or freshwater environments, although a small number have adapted to life on land.
Scientists estimate that there are over 67,000 known species of crustaceans. They are characterized by:
- A hard exoskeleton
- Jointed limbs
- Segmented bodies
Fossil evidence shows that crustaceans have existed since the Cambrian period, making them one of the oldest animal groups still living today.
List of Common Crustaceans
- Barnacle
- Beach Flea
- Copepod
- Crab
- Crayfish (also called crawfish in some regions)
- Dublin Bay Prawn
- Freshwater Shrimp
- Goose Barnacle
- Gribble
- Hermit Crab
- King Prawn
- Koura
- Krill
- Land Crab
- Langoustine
- Lobster
- Norway Lobster
- Opossum Shrimp
- Oyster Crab
- Prawn
- Robber Crab
- Sand Hopper
- Sand Shrimp
- Shrimp
- Soft-Shell Crab
- Spiny Lobster
- Water Flea
- Woodlouse
Common Crustaceans: Facts & Descriptions
Crab
Crabs are decapod crustaceans, meaning they have ten legs. Although they can walk in any direction, they are best known for moving sideways. Female crabs can release thousands of eggs at once, but only a small number survive beyond the larval stage. Smaller crab species usually live for 3–4 years.
Lobster
Lobsters are large decapod crustaceans and are well known as a luxury seafood today. Historically, however, they were once considered food for the poor. Lobsters can swim both forward and backward and use this ability to escape predators.
Shrimp
There are over 2,000 species of shrimp found worldwide. They live in oceans, rivers, and lakes, from shallow waters to deep sea floors. Depending on the species, shrimp can live 1–7 years and may grow up to 20 cm in length.
Prawn
Prawns look very similar to shrimp, but they are not the same type of crustacean. The main differences are that prawns are often larger than shrimp and have a branched gill structure. Prawns also tend to prefer warmer waters.
Hermit Crab
Hermit crabs are omnivores, feeding on algae, plants, and small animals. They are not true crabs because they cannot produce a hard shell of their own. Instead, they protect their soft bodies by living inside empty shells. Hermit crabs are a different group of crustaceans from true crabs, not a single species.
Krill
Krill are small crustaceans that play a vital role in the ocean food chain. They feed on phytoplankton and algae and are often eaten by larger fish, whales, and seabirds. Krill travel in huge swarms, sometimes numbering in the millions, which helps some individuals survive despite heavy predation.
Types of Crustaceans
Branchiopoda
Includes small freshwater crustaceans such as water fleas.
Ostracods
Very small crustaceans, often called seed shrimp, usually about 1 mm in size.
Remipedia
Long, blind crustaceans typically found in saline groundwater environments.
Maxillopoda
A diverse group that includes barnacles and copepods, with varied body forms.
Malacostracans
The largest and most familiar group, including crabs, lobsters, shrimp, and prawns.