The brown crab, or cancer pagurus, is also known as the edible crab. It mainly inhabits shallow waters in the northern Atlantic Ocean and the North Sea. Fisheries in the British Isles rely on the brown crab for the majority of their commercial trade. Europeans are the main consumers of this tasty crustacean.
A crab’s shell is made of calcium and chitin. The young brown crab’s shell is purplish brown and becomes reddish brown when it reaches maturity. Like all crustaceans, the brown crab molts as it grows, shedding its shell to accommodate new growth. After the old carapace is shed, the new shell remains soft for a few days, leaving the crab in a vulnerable state until it hardens.
Mature brown crabs may measure a foot (30 cm) wide and weigh 6.6 pounds (3 kg). The brown crab has 10 legs and an average life span of 15 years, while some edible crabs have been known to live for 20. It has two eyes located on stalks, and moves by walking sideways.
Brown crabs are nocturnal, hiding among rocks during the day and then emerging at night to feed. The claws of the brown crab are powerful and can easily crush the shells of the mollusks and crustaceans that comprise the majority of its diet. Its main predator is the octopus.
Female edible crabs burrow into the sandy sea bottom and remain there for approximately five months as they wait for their eggs to hatch. A female brown crab can produce up to 20,000 eggs at one time. The newly hatched larvae drift on the water as small organisms known as plankton. They are preyed upon by shrimp, fish, whales, crustaceans and other creatures that eat plankton, while the juvenile crabs are eaten by seabirds.
The brown crab is usually caught in a baited trap called a crab pot. This is a square wire frame with one or more entrances. A crab can easily crawl through the openings to get to the food, but the pot is designed so that it is impossible for the crab to get back out.
In some parts of the world, brown crabmeat is considered a delicacy. The claws contain white meat, while the meat in the body is brown. Crabmeat is high in protein, and low in fat and calories. It is nutritious, being a source of essential fatty acids and other nutrients which include potassium, phosphorus, iron, and zinc. Crabmeat also provides calcium, magnesium, selenium, and vitamins B12 and C.