Japanese spider crab
Encyclopedia
The , Macrocheira kaempferi, is a species
of marine
crab
that lives in the waters around Japan
. It has the largest leg span of any arthropod
, reaching up to 3.8 metres (12.5 ft) and weighing up to 41 pounds (18.6 kg). It is the subject of small-scale fishery
.
width) and the whole crab can weigh up to 41 pounds (18.6 kg). It is the males which have the longest chelipeds; females have much shorter chelipeds, which are shorter than the following pair of legs. Apart from its outstanding size, the Japanese spider crab differs from other crabs in a number of ways. The first pleopods of males are unusually twisted, and its larvae
appear primitive. The crab is orange, with white spots along the legs. It is reported to have a gentle disposition "in spite of its ferocious appearance".
, from Tokyo Bay
to Kagoshima Prefecture
. Outlying populations have been found in Iwate Prefecture
and off Su-ao
in Taiwan
. Adults can be found at depths of up to 600 metres (1,968.5 ft), or as shallow as 50 metres (164 ft).
, the Japanese spider crab feeds on shellfish
and animal carcasses
and may live for up to 100 years. Development of the plankton
ic larvae is temperature dependent and takes between 54 and 72 days at 12–15 °C (53.6–59 F).
in 1836 by Coenraad Jacob Temminck
under the name Maja kaempferi, based on material from Philipp Franz von Siebold
collected near the artificial island Dejima
. The specific epithet commemorates Engelbert Kaempfer
, a German naturalist who lived in Japan from 1690 to 1692 and wrote about the country's natural history
. It was moved to the genus Inachus
by Wilhem de Haan
in 1839, but placed in a new subgenus, Macrocheira. That subgenus was raised to the rank
of genus in 1886 by Edward J. Miers
. Although currently placed in the family Inachidae
, M. kaempferi does not fit cleanly into that group, and it may be necessary to erect a new family just for the genus Macrocheira. As well as the single extant species, four species belonging to the genus Macrocheira are known from fossil
s.
is centred around Suruga Bay
, and the population has decreased in number, forcing fishermen into exploring deeper waters in order to catch them. The average size caught by fishermen is a leg span of 1–1.2 m (3.3–3.9 ).
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 marine
Marine biology
Marine biology is the scientific study of organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather...
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...
that lives in the waters around 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...
. It has the largest leg span of any arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
, reaching up to 3.8 metres (12.5 ft) and weighing up to 41 pounds (18.6 kg). It is the subject of small-scale fishery
Crab fisheries
Crab fisheries are fisheries which capture or farm crabs. True crabs make up 20% of all crustaceans caught and farmed worldwide, with about 1.4 million tonnes being consumed annually. The horse crab, Portunus trituberculatus accounts for one quarter of that total...
.
Description
The Japanese spider crab has the greatest leg span of any arthropod, reaching 3.8 metres (12.5 ft) from claw to claw. The body may grow to a size of 40 centimetres or 16 in (carapaceCarapace
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...
width) and the whole crab can weigh up to 41 pounds (18.6 kg). It is the males which have the longest chelipeds; females have much shorter chelipeds, which are shorter than the following pair of legs. Apart from its outstanding size, the Japanese spider crab differs from other crabs in a number of ways. The first pleopods of males are unusually twisted, and its larvae
Crustacean larvae
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow...
appear primitive. The crab is orange, with white spots along the legs. It is reported to have a gentle disposition "in spite of its ferocious appearance".
Distribution
Japanese spider crabs are mostly found off the southern coasts of the Japanese island of HonshūHonshu
is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...
, from Tokyo Bay
Tokyo Bay
is a bay in the southern Kantō region of Japan. Its old name was .-Geography:Tokyo Bay is surrounded by the Bōsō Peninsula to the east and the Miura Peninsula to the west. In a narrow sense, Tokyo Bay is the area north of the straight line formed by the on the Miura Peninsula on one end and on...
to Kagoshima Prefecture
Kagoshima Prefecture
is a prefecture of Japan located on the island of Kyushu. The capital is the city of Kagoshima.- Geography :Kagoshima Prefecture is located at the southwest tip of Kyushu and includes a chain of islands stretching further to the southwest for a few hundred kilometers...
. Outlying populations have been found in Iwate Prefecture
Iwate Prefecture
is the second largest prefecture of Japan after Hokkaido. It is located in the Tōhoku region of Honshū island and contains the island's easternmost point. The capital is Morioka. Iwate has the lowest population density of any prefecture outside Hokkaido...
and off Su-ao
Su-ao, Yilan
Su-ao , located in southern Yilan County, Taiwan, is an urban township that is famous for its seafood restaurants and cold springs. It is the destination of National Highway No. 5, Su-ao-Hualian Express Way, and North-Link Line of Taiwan Railway Administration...
in 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...
. Adults can be found at depths of up to 600 metres (1,968.5 ft), or as shallow as 50 metres (164 ft).
Life cycle
In its natural habitatHabitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
, the Japanese spider crab feeds on shellfish
Shellfish
Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...
and animal carcasses
Cadaver
A cadaver is a dead human body.Cadaver may also refer to:* Cadaver tomb, tomb featuring an effigy in the form of a decomposing body* Cadaver , a video game* cadaver A command-line WebDAV client for Unix....
and may live for up to 100 years. Development of the plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic larvae is temperature dependent and takes between 54 and 72 days at 12–15 °C (53.6–59 F).
Taxonomic history
The Japanese spider crab was originally describedAlpha 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...
in 1836 by Coenraad Jacob Temminck
Coenraad Jacob Temminck
Coenraad Jacob Temminck was a Dutch aristocrat and zoologist.Temminck was the first director of the National Natural History Museum at Leiden from 1820 until his death. His Manuel d'ornithologie, ou Tableau systematique des oiseaux qui se trouvent en Europe was the standard work on European birds...
under the name Maja kaempferi, based on material from Philipp Franz von Siebold
Philipp Franz von Siebold
Philipp Franz Balthasar von Siebold was a German physician and traveller. He was the first European to teach Western medicine in Japan...
collected near the artificial island Dejima
Dejima
was a small fan-shaped artificial island built in the bay of Nagasaki in 1634. This island, which was formed by digging a canal through a small peninsula, remained as the single place of direct trade and exchange between Japan and the outside world during the Edo period. Dejima was built to...
. The specific epithet commemorates Engelbert Kaempfer
Engelbert Kaempfer
Engelbert Kaempfer , a German naturalist and physician is known for his tour of Russia, Persia, India, South-East Asia, and Japan between 1683 and 1693. He wrote two books about his travels...
, a German naturalist who lived in Japan from 1690 to 1692 and wrote about the country's natural history
Natural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...
. It was moved to the genus Inachus
Inachus (crab)
Inachus is a genus of crab, containing the following species:*Inachus aguiarii Brito Capello, 1876*Inachus angolensis Capart, 1951*Inachus biceps Manning & Holthuis, 1981*Inachus communissimus Rizza, 1839...
by Wilhem de Haan
Wilhem de Haan
Wilhem de Haan was a Dutch zoologist. He specialised in the study of insects and crustaceans, and was the first keeper of invertebrates at the Rijksmuseum in Leiden, now Naturalis. He was forced to retire in 1846, when he was partially paralysed by a spinal disease...
in 1839, but placed in a new subgenus, Macrocheira. That subgenus was raised to the rank
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
of genus in 1886 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...
. Although currently placed in the family Inachidae
Inachidae
Inachidae is a family of crabs, containing 39 genera:*Achaeopsis Stimpson, 1857*Achaeus Leach, 1815*Anisonotus A. Milne-Edwards, 1879*Anomalothir Miers, 1879*Bothromaia Williams & Moffitt, 1991...
, M. kaempferi does not fit cleanly into that group, and it may be necessary to erect a new family just for the genus Macrocheira. As well as the single extant species, four species belonging to the genus Macrocheira are known from fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s.
Fishery
Temminck, in his original description, noted that the crab was known to the Japanese for the serious injuries it can cause with its strong claws. Nonetheless, the Japanese spider crab is "occasionally collected for food"; a total of 24.7 tonnes (54,454.2 lb) was collected in 1976, but only 3.2 tonnes (7,054.8 lb) in 1985. FisheryCrab fisheries
Crab fisheries are fisheries which capture or farm crabs. True crabs make up 20% of all crustaceans caught and farmed worldwide, with about 1.4 million tonnes being consumed annually. The horse crab, Portunus trituberculatus accounts for one quarter of that total...
is centred around Suruga Bay
Suruga Bay
Suruga Bay is a bay on the Pacific coast of Honshū in Shizuoka Prefecture, Japan. It is situated north of an imaginary line joining Omaezaki Point and Irōzaki Point at the tip of the Izu Peninsula and surrounded by Honshū to the southwest and west and the Izu Peninsula to the east.-Geology:Suruga...
, and the population has decreased in number, forcing fishermen into exploring deeper waters in order to catch them. The average size caught by fishermen is a leg span of 1–1.2 m (3.3–3.9 ).
See also
- Largest arthropods
- Spider crab (disambiguation)
- Fauna JaponicaFauna JaponicaFauna Japonica is a series of monographs on the zoology of Japan.The full title is Fauna Japonica sive Descriptio animalium, quae in itinere per Japoniam, jussu et auspiciis superiorum, qui summum in India Batava imperium tenent, suscepto, annis 1825 - 1830 collegit, notis, observationibus et...