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Sunday, July 23, 2017

Species Fact Profile: Japanese Spider Crab (Macrocheira kaempferi)

Japanese Spider Crab
Macrocheira kaempferi (Temminck, 1836)

Range: Japan's Pacific Coast (Islands of Konshu and Kyushu)
Habitat: Continental Shelves with Sandy or Rocky Bottoms
Diet: Carrion, Small Invertebrates, Kelp, Algae
Social Grouping: Asocial
Reproduction: Mate in the spring (January through March).  Packets of sperm (called spermatohores) are inserted into the female's body.  Females may lay over one million eggs per season, less than 1 millimeter in diameter, which she carriers on her body.  Eggs hatch after 10 days, after which there is no parental care.
Lifespan: 50-100 Years (Speculation)
Conservation Status: Not Evaluated

  • Largest (but not heaviest) living arthropod with longest legspan - up to 4 meters from the tip of one leg to the tip of the opposite.  Pear-shaped body is up to 37 centimeters long.  Females are wider but slightly smaller than males with shorter legs.  Weigh up to 20 kilograms
  • Color is mottled red-orange, usually fading int a cream color on the underside.  Colors tend to be brighter after a molt
  • The long legs are very fragile and somewhat weak.  Most crabs are missing at least one due to predation or getting tangled in nets; legs grow back with molts
  • Folk tales describe spider crabs seizing sailors and dragging them underwater to eat; unlikely to be true, but have have been inspired by sights of crabs scavenging drowned humans
  • Adults have few predators.  As such, they do not camouflage themselves by decorating their shells with sponges and other items as many other crabs due
  • Specimens have occasionally been found at a considerable distance from Japan, as far as Taiwan - it's likely that these individuals were carried there either by fishing trawlers or by extreme weather conditions
  • Considered a delicacy in Japan, though catch has declined significantly in recent years.  Law prohibits fishing for them during the mating season

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