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Squat lobster

life science Maturity 7-9 Next article →

Squat lobsters are fascinating sea creatures that live in oceans all over the world. They are part of a group called Anomura, which includes hermit crabs and mole crabs. These animals are shaped like a mix between a true lobster and a crab. Their bodies are flattened from top to bottom, a shape known as being dorsoventrally flattened. They can be found in many different places in the ocean. Some live near the surface, while others live near deep hydrothermal vents. One amazing species even lives in caves above sea level.

Expl1573 - Flickr - NOAA Photo Library
Expl1573 - Flickr - NOAA Photo Library

A squat lobster's body has two main parts. The first part is the cephalothorax, which is the head and chest combined. This part is covered by a hard shell called a carapace. The second part is the pleon, or the abdomen. The pleon is usually curled tightly under the cephalothorax. The cephalothorax has 19 segments, though they are hard to see. It also has many appendages, like antennae and mouthparts. These mouthparts do more than just handle food. They can also help the animal sort through sediment or gather particles.

Kiwa puravida
Kiwa puravida

Scientists have studied these animals to learn about their many different types. There are more than 900 described species in about 60 different genera. If we include the Aeglidae family, that number rises to over 1,000 species. In 2020, a study found that these creatures are even more diverse than we once thought. This study described 16 new species in the Leiogalathea genus. Researchers also found that there are fewer species in the Atlantic Ocean than in the Pacific Ocean. These discoveries help us understand how life is spread across our blue planet.

Squat lobsters have many special tools for living in the sea. Their most noticeable legs are the first pair, called chelipeds. These legs end in claws, or chelae, that can be six times longer than the body. They use these large claws to catch prey or to look big to predators. They also have smaller legs used for walking. A tiny fifth pair of legs is tucked under the shell. These small legs are used to clean the body and the gills.

Porcelain crab Nick Hobgood
Porcelain crab Nick Hobgood

Many squat lobsters like to live in large groups called aggregations. They often gather in areas with lots of food, like shipwrecks or whale falls. Some species, like Munida gregaria, form massive swarms in the water. These swarms can be 200 meters tall and 10 kilometers wide. Other species stay on the sea floor near structures like coral. This behavior helps them find food and stay safe from enemies. Even though they look like lobsters, they are actually closer relatives to the hermit crab.

Expl1573 - Flickr - NOAA Photo Library
Expl1573 - Flickr - NOAA Photo Library
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Kiwa puravida.tif
File:Expl1573 - Flickr - NOAA Photo Library.jpg
Expl1573 - Flickr - NOAA Photo Library.jpg
File:Porcelain crab Nick Hobgood.jpg
Porcelain crab Nick Hobgood.jpg
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