Portunus trituberculatus, the gazami crab, Japanese blue crab or horse crab, is the most widely fished

Fishery

Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of crab

Crab

True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

 in the world. It is found off the coasts of East Asia

East Asia

East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...

 and is closely related to Portunus pelagicus

Portunus pelagicus

Portunus pelagicus, also known as the flower crab, blue crab, blue swimmer crab, blue manna crab or sand crab, is a large crab found in the intertidal estuaries of the Indian and Pacific Oceans and the Middle-Eastern coast of the Mediterranean Sea. The name "flower crab" is used in east Asian...

.

Fishery

P. trituberculatus is the world's most heavily fished crab species, with over 300,000 tonne

Tonne

The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...

s being caught annually, 98% of it off the coast of China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

.

Distribution

P. trituberculatus is found off the coasts of Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, Korea

Korea

Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...

, China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 and Taiwan

Taiwan

Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

.

Description

The carapace

Carapace

A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...

 may reach 15 centimetres (5.9 in) wide, and 7 cm (2.8 in) from front to back. P. trituberculatus may be distinguished from the closely related (and also widely fished) P. pelagicus

Portunus pelagicus

Portunus pelagicus, also known as the flower crab, blue crab, blue swimmer crab, blue manna crab or sand crab, is a large crab found in the intertidal estuaries of the Indian and Pacific Oceans and the Middle-Eastern coast of the Mediterranean Sea. The name "flower crab" is used in east Asian...

by the number of broad teeth on the front of the carapace (3 in P. trituberculatus, 4 in P. pelagicus) and on the inner margin of the merus

Arthropod leg

The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...

 (4 in P. trituberculatus, 3 in P. pelagicus).

Taxonomy

P. trituberculatus was first described

Alpha taxonomy

Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...

 by Edward J. Miers

Edward J. Miers

Edward John Miers F.Z.S. F.L.S. was a British zoologist and curator of the crustacean collection at the Natural History Museum in London...

in 1876, under the name Neptunus trituberculatus.