Animals can be categorized by their body characteristics, including how segmented they are and their types of legs. One such categorization is crustaceans. Crabs are probab ly one of the most common examples of crustaceans, however, there are around 80,000 other known crustaceans on earth.
These animals are ancient, with the most common ones appearing millions of years ago. For example, lobsters first existed during the Cretaceous Period and crabs first appeared during the Jurassic Period. It’s no surprise so many different species have evolved!
Let’s find out what makes an animal a crustacean and learn more about some of the different species.
What is a Crustacean?
Crustaceans have hard exteriors (or exoskeletons) and segmented bodies. They are part of the larger group of arthropod animals. However, they are distinct from other arthropods due to their two pairs of antennae or feelers and jointed legs splitting into two branches, also known as biramous legs.
These animals hatch from eggs and, as their bodies grow, they can shed or molt their exoskeleton to accompany the growth. Crustaceans range in size from being large with 12 feet long legs to so small they can live in between sand grains.
Most crustaceans live in the water, also known as being fully aquatic. You can find them in freshwater or saltwater environments. However, some are semi-aquatic or land-dwelling. Most land crustaceans live in muddy, sandy, or rocky areas.
15 Examples of Crustaceans
Here is a list of 15 well-known and maybe not-so-well-known crustaceans. Check out their pictures and learn more about each of these types of arthropods.
1. American Lobster
Scientific name: Homarus americanus
The American lobster is a well-known crustacean found along North America’s Atlantic coast. These lobsters can live for at least 100 years, five times longer than most other lobster species.
American lobsters are the heaviest crustacean and arthropod globally, weighing an average of between one and nine pounds. The heaviest caught American lobster was 44 pounds. They also have distinctive giant claws: one for crushing prey and the other with sharp edges to hold and tear prey.
2. Japanese Spider Crab
Scientific name: Macrocheira kaempferi
Japanese spider crabs get their name from their long 12-foot legs, giving them a spider-like resemblance. Their legs allow them to move quickly to stalk prey. It also makes them the largest living crustacean and arthropod.
These crabs are omnivorous, feeding on dead animals, shellfish, plants, algae, and small fish. You can find them deep in the ocean, averaging at 344 to 984 feet or up to 1,000 feet in depth.
3. Pea Crab
Scientific name: Pinnotheres pisum
The smallest known crab in the world is the Pea crab. These crustaceans are the size of a pea, with females at around 0.5 inches and males around 0.24 inches.
They mostly live along the coastlines of the United Kingdom and Eastern Europe. A unique habit of this crab is that the female is a parasitic organism, making a home inside other creatures for food, shelter, and oxygen. You can often find female pea crabs in oysters, clams, and mussels.
Scientific name: Oniscidea
There are around 3,000 species of woodlouse found on every continent worldwide except Antarctica. They are herbivores eating decaying leaves and plant matter in dark and moist environments. You can often find them hiding under stones, in walls, or in compost heaps.
Although commonly mistaken for insects, woodlice are land-dwelling crustaceans with 14 parts to their bodies. This feature allows them to curl into a ball for protection.
5. Slipper Lobster
Scientific name: Scyllaridae
Slipper lobsters are mostly found in the Pacific islands in shallow lagoon water and crevices of reefs, warm oceans, or seas. They are bottom dwellers that can live at depths up to 1,600 feet.
Although called “lobsters,” these crustaceans are not considered true lobsters. Their bodies are spiny, furry, more flattened, and don’t have large claws. They do, however, taste very similar to lobsters.
6. Pistol Shrimp
Scientific name: Alpheidae
While there are many shrimp species, pistol shrimps are quite unique. They have a snapping claw that creates a bubble jetting out at 105 feet per second to kill prey. It creates a snapping or pistol-like sound, loud enough to break glass jars.
These shrimp live in shallow ocean waters in tropical and subtropical regions. They are well adapted to swimming since they have pleopods that are forked swimming limbs.
7. Tadpole Shrimp
Scientific name: Triops longicaudatus
These small crustaceans are in the Branchiopoda class and live in freshwater habitats, unlike most saltwater shrimp. They are golden brown and have an elongated abdomen with two long tails and legs with feathery gills.
These small 1.5-inch shrimp are omnivores, eating algae, worms, mosquito larvae. However, they can also be cannibalistic. Tadpole shrimp are one of the oldest known species worldwide, having existed at least 220 million years ago.
Scientific name: Euphausiacea
Krills are one of the most important animals in the ecosystem of the deep and coastal oceans where they live. They are a common food source for whales, birds, seals, and fish, especially in the harsh Antarctic and Arctic waters where food options are scarce.
These small crustaceans uniquely have transparent bodies with specially evolved organs that emit light, also known as being bioluminescent. It is believed they produce light to camouflage themselves or communicate with other krills. They can grow up to 2.4 inches and can live up to six years.
Scientific name: Cirripedia
Yes, barnacles are crustaceans. These animals start their life as free-swimming larvae with many crustacean characteristics. They eventually find a place to settle and attach themselves using their first antennae.
During this stage, they morph into the post-larval stage we commonly see. Once in the post-larval stage, they spend the remainder of their lives anchored to hard surfaces, such as rocks, buoys, and the bottom of boats.
10. Hermit Crab
Scientific name: Paguroidea
Hermit crabs can be found in shallow, coastal waters worldwide and there are more than 1000 different species. They are considered “false crabs” because they can’t grow their own shells and have soft bodies with only a hard exoskeleton in the front.
Hermit crabs get their names from the shells they carry on their backs to protect their soft bodies. They periodically swap out these mollusk shells as they grow and often inspect new shells thoroughly before selecting them. Competition for shells is fierce and can even lead to fights!
11. Water Fleas
Scientific name: Daphnia
Water fleas are common worldwide and enjoy freshwater habitats such as slow-moving rivers and shoreline areas of lakes or ponds. These small crustaceans grow between 0.007 inches to 0.2 inches. They can uniquely change their shape and size in response to their environment. For example, their heads can grow helmet-like features to make them less attractive as a food source.
Scientific name: Remipedia
Remipedes are cave-dwelling, blind animals that are the only known venomous crustaceans. They have two pairs of maxillae with fang-like projections. These fangs inject a paralyzing chemical that kills their prey.
These crustaceans look like worms but have long bodies with 10 to 32 segments and four antennae, with a pair being feathery and long. They are small, growing around 0.35 to 1.8 inches.
Scientific name: Cambarus
Crayfish live in streams, ponds, rivers, and lakes throughout the world and mostly in the United States. You typically find them under submerged logs or rocks. They are also considered invasive species in areas such as Europe, China, and North America. For example, they commonly consume the local rice crops in China causing economic issues.
These 3-inch long animals spend most of their time foraging for various food types, including plants and animal materials. Some species can live up to 20 years!
14. Common Yabby
Scientific name: Cherax destructor
Common yabbies are freshwater crustaceans from Australia that are classified as a vulnerable crayfish species. Although found in waterways, they can survive for at least several years in dry conditions. They do this by lying dormant in burrows deep in swamp beds or muddy creeks.
The common yabby color varies depending on its habitat and the clarity of the water. It can range from black or dark brown in clear waters to green-brown or beige in cloudy waters.
15. Whale Lice
Scientific family: Cyamidae
Whale lice are small crustaceans ranging from 0.2 to 1 inch in length. However, they are the largest known arthropod living on the bodies of mammals, such as whales, dolphins, and porpoises. They are actually responsible for the distinctive white patches on the Eubalaena genus of whales.
These animals cling onto skin, wrinkles, or barnacles and feed on algae or dead skin on their hosts, causing no harm to the host animals. Each specific whale lice species in this family usually lives on a single species of host.