Some crabs look like spiders.
They live in the deep sea.
Some are very, very big.
They swim and crawl on the bottom.
It is fun to see them.
Can you find a crab?
Some crabs look like spiders.
These crabs live in the sea. One kind is the Japanese spider crab. It is the biggest crab alive. It lives on the ocean floor.
Other crabs live in the North Sea. Some crabs live near North America. In Australia, crabs pile up on each other. Fast crabs climb over slow ones. It is a busy sight to see!
Majoidea is a large group of crabs. This group includes spider crabs. It also includes decorator crabs. Scientists divide these crabs into many families. Some families are called Epialtidae and Inachidae. Others are called Inachoididae and Macrocheiridae. There are also Majidae crabs. These are called "true" spider crabs.
Some of these crabs are very big. The Japanese spider crab is a famous kind. It is the largest crab alive today. It lives on the bottom of the Pacific Ocean.
Other crabs live in different places. The portly spider crab lives near North America. The great spider crab lives in the North Sea. You can also find the European spider crab.
In Australia, crabs act in a funny way. They pile up on top of each other. The fast crabs climb over the slow ones. This happens near Tasmania. One very old kind of crab lived a long time ago. It lived in France during the Cenomanian period. We call this kind Priscinachus elongatus.
Majoidea is a huge group of crabs. It includes spider crabs and decorator crabs. These crabs are very special living things. Scientists group them together in a superfamily. This group is important for learning about sea life. There are many different kinds within this group.
Scientists organize these crabs into different families. A researcher named De Grave and his team studied them. They first divided them into six families. Later, scientists changed how they group them. Some groups became their own families. Others moved to different superfamilies. This helps us understand how they are related.
Many people have named these crab families over time. MacLeay named Epialtidae and Inachidae in 1838. Dana named Inachoididae and Macrocheiridae in 1851. Samouelle named the Majidae family in 1819. These are the "true" spider crabs. Balss named Mithracidae in 1929. Garth named Oregoniidae in 1958. Breton named Priscinachidae in 2009.
Some crabs in this group are very famous. The Japanese spider crab is the largest crab alive. It lives on the Pacific Ocean floor. The portly spider crab lives near North America. You can find the great spider crab in the North Sea. Another kind is the European spider crab. One old kind lived in France. It is called Priscinachus elongatus.
These crabs live in many different homes. Some live in the deep, dark ocean. Others live in places where rivers meet the sea. Australian spider crabs live near Tasmania. These crabs like to pile up on each other. Fast crabs climb over the slow ones. It is a very busy sight to see.
Majoidea is a large superfamily of crabs. This group includes both spider crabs and decorator crabs. Scientists study these animals to understand how different crustacean species are related. They are important members of marine ecosystems around the world. By studying Majoidea, researchers can learn more about the history of life in the sea.
Taxonomy is the science of naming and classifying living things. Scientists use taxonomy to organize animals into groups based on their traits. Researchers like De Grave have worked to define these groups. Originally, De Grave and his colleagues divided Majoidea into six specific families. However, scientific understanding often changes as new information is discovered. This led to revisions in how these crabs are classified.
Recent changes have altered the family structure of Majoidea. For example, the subfamilies Epialtinae and Mithracinae were elevated to full families. At the same time, the group Hymenosomatidae was moved into its own separate superfamily. The World Register of Marine Species currently recognizes several distinct families. These include Epialtidae and Inachidae, both named by MacLeay in 1838. Inachoididae and Macrocheiridae were named by Dana in 1851.
Other families within the superfamily have different histories. The family Majidae was named by Samouelle in 1819. These are often called the "true" spider crabs. Mithracidae was named by Balss in 1929. Oregoniidae was named by Garth in 1958. The most recent addition is Priscinachidae, named by Breton in 2009. This family is very small. It is represented by only one single species.
Some species in Majoidea are truly remarkable in size and habitat. The Japanese spider crab, known as Macrocheira kaempferi, is very famous. It is the largest living species of crab in the world. You can find these giants on the bottom of the Pacific Ocean. Another notable species is Libinia emarginata. It is commonly called the portly spider crab. This species lives in estuarine habitats along the east coast of North America.
Different environments support many different types of these crabs. The genus Hyas includes the great spider crab, or Hyas araneus. These can be found in the Atlantic and the North Sea. There is also a species called Maja squinado. People sometimes call it the European spider crab. In other parts of the world, you might find Australian spider crabs near Tasmania. These crabs show very interesting social behaviors.
Australian spider crabs are known for how they move together. They often pile up on top of one another in large groups. The faster-moving crabs will climb over the smaller, slower crabs. This behavior creates a moving mass of crustaceans. This group of crabs shows how diversity can exist in both shape and behavior. From the deep Pacific to the North Sea, Majoidea are a widespread and fascinating part of our oceans.
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