What Is a Squat Lobster?

In their book The Biology of Squat Lobsters, Poor, et. al. say that despite the fact that many have not heard of them, squat lobsters are far from hidden. They say they are

"dominant, numerous and highly visible crustaceans on seamounts, continental margins, many shelf environments and coral reefs at all depths, and at hydrothermal vents."

These often colorful animals are also featured in many underwater photos and video.

Squat Lobster Species

There are over 900 species of squat lobsters, and it is thought that there are many more yet to be discovered. One of the most famous squat lobsters in recent times is the yeti crab, which was discovered during surveys conducted in conjunction with the Census of Marine Life. 

Identification

Squat lobsters are small, often colorful animals. They can be less than one inch to about 4 inches in length, depending upon the species. Squat lobsters have 10 legs. The first pair of legs are very long and contain claws.  The three pairs of legs after that are used for walking. The fifth pair has small claws and may be used for cleaning gills. This fifth pair of legs is much smaller than the legs in "true" crabs.  

Squat lobsters have a short abdomen that is folded under their body. Unlike lobsters and crayfish, squat lobsters don't have true uropods (the appendages that form the tail fan). 

Lobster Cocktail?

Squat lobsters are in the infraorder Anomura - many of the animals in this infraorder are called "crabs," but they are not true crabs. They aren't lobsters, either. In fact, squat lobsters are more closely related to hermit crabs than to lobsters (e.g., the American lobster). In the seafood world, they may be marketed as langostino lobsters (langostino is Spanish for "prawn") and even sold as shrimp cocktail.

Classification

• Kingdom: Animalia
• Phylum: Arthropoda
• Subphylum: Crustacea
• Class: Malacostraca
• Subclass: Eumalacostraca
• Order: Decapoda
• Infraorder: Anomura
• Families: Chirostylidae and Galatheidae

Habitat and Distribution

Squat lobsters live in oceans around the world, with the exception of the coldest Arctic and Antarctic waters.  They can be found on sandy bottoms and hidden in rocks and crevices. They also may be found in the deep sea around seamounts, hydrothermal vents and in underwater canyons.

Feeding

Depending on the species, squat lobsters may eat plankton, detritus or dead animals.  Some feed on bacteria at hydrothermal vents. Some (e.g., Munidopsis andamanica) are even specialized to eat wood from sunken trees and shipwrecks. 

Reproduction

The reproductive habits of squat lobsters are not well known. Like other crustaceans, they lay eggs. The eggs hatch into larvae that eventually develop into juvenile, and then adult, squat lobsters. 

Conservation and Human Uses

Squat lobsters are relatively small, so fisheries around them have not developed in many areas. However, as mentioned above, they may be harvested and sold as cocktail shrimp or in "lobster" dishes, and can be used as feed stock for chickens and at fish farms.

References and Further Information

• Aquarium of the Pacific. Squat Lobster. Accessed April 29, 2014.
• Bok, M. 2010. Wood-eating Squat Lobsters of the Deep. Arthropoda Blog. Accessed April 29, 2014.
• Kilgour, M. 2008. Squat Lobsters: More Questions Than Answers. NOAA Ocean Explorer. Accessed May 5, 2014. 
• McLaughlin, P., S. Ahyong & J.K. Lowry (2002 onwards). Anomura: Families. Version: 2 October 2002. http://crustacea.net.
• Poor, G., Ahyong, S. and J. Taylor. 2011. The Biology of Squat Lobsters. Accessed online via Google Books, April 29, 2014.
• Schmidt, C. 2007. No Matter What You Call It, 'Squat' Isn't Lobster. Wild Catch Magazine. Accessed April 29, 2014.
• WoRMS. 2014. Anomura. Accessed through World Register of Marine Species, May 5, 2014.