Giant Spider Crab
Macrocheira kaempferi
The giant spider crab is the largest known species of crab and may live up to 100 years. The Japanese name for this species is ‘taka-ashi-gani’ literally translating to “tall legs crab.”
Credit: Aquarium of the Pacific/Robin Riggs
SPECIES IN DETAIL
Giant Spider Crab
Macrocheira kaempferi
CONSERVATION STATUS: Not evaluated
CLIMATE CHANGE:
At the Aquarium
The giant spider crab is found in the Northern Pacificgallery.
Geographic Distribution
They are found on the Pacific side of the Japanese islands (Konshu and Kyushu), usually at a latitude between 30 and 40 degrees north. They are found most often in the Sagami, Suruga, and Tosa bays, as well as off the coast of the Kii peninsula.
Habitat
They most often stay in the sandy, rocky bottom of the continental shelf and slope at a depth of 150—300 meters (492.13—984.25 feet), though they have been found at depths of 182.88 meters (600 feet). During mating season, they spend most of their time in shallower 50 meters (164.04 feet) water depths. Younger crabs tend to live in shallower areas with warmer temperatures.
Physical Characteristics
Male and female spider crabs range from dark orange to tan and are known for having long spider-like legs. Females have smaller, wider abdomens than the males. Additionally, the female chelipeds (claw bearing legs) tend to be shorter than the males. Due to their long limbs and poor joints they are often found with missing legs.
Size
Range mass: 16 to 20 kilograms (35.24 to 44.05 pounds) Range length: 3.7 meters (12.14 feet) Average length: 3 meters (9.84 feet)
Diet
Giant spider crabs are omnivorous scavengers, eating both plant and animal matter. They don’t hunt their food like most animals, instead, they scurry along the floor and pick up mollusks like clams and mussels as well as dead or decaying organisms. They occasionally eat kelp and algae if it is found.
Reproduction
These crabs mate once a year in early spring (January to March) at the depth of 50 meters (164.04 feet). During their mating season, it is illegal to catch spider crabs in Japan. Though not much is known about their breeding ritual, it is known that they move to shallower waters where the females and males meet, and the male delivers spermatophores into the female’s abdomen. The female can lay up to 1.5 million eggs but only a few will survive. She will carry the eggs on her back until they hatch. Once their eggs hatch, crab larvae receive no parental care.
Behavior
These crabs are placid animals who remain calm and are not easily upset. They spend the majority of their time scavenging for food. Many juvenile spider crabs decorate themselves for camouflage using their chelae (claws); the crabs tear up objects and attach them to the hooked barbs on their rostrum and carapace. When they mate, they migrate to shallower waters of 50 meters (164.04 feet).
Adaptation
They have a hard, armored exoskeleton that helps protect them from large predators like octopuses. Despite their large size, spider crabs are able to camouflage with their surroundings. They blend their body parts in with the rocky habitat or decorate their shells with sponges and other detritus accessible to them. Spider crabs are able to survive with many legs missing, and they can regrow them over time with successive molts.
Longevity
Little is known about their longevity, but it is often reported that they can live from 50—100 years in their natural environment.
Conservation
Conservation efforts focus on preventing overfishing of these crabs. It is illegal to catch them during mating season.
SPECIES IN DETAIL | Print full entry
Giant Spider Crab
Macrocheira kaempferi
CONSERVATION STATUS: Not evaluated
CLIMATE CHANGE:
The giant spider crab is found in the Northern Pacificgallery.
They are found on the Pacific side of the Japanese islands (Konshu and Kyushu), usually at a latitude between 30 and 40 degrees north. They are found most often in the Sagami, Suruga, and Tosa bays, as well as off the coast of the Kii peninsula.
They most often stay in the sandy, rocky bottom of the continental shelf and slope at a depth of 150—300 meters (492.13—984.25 feet), though they have been found at depths of 182.88 meters (600 feet). During mating season, they spend most of their time in shallower 50 meters (164.04 feet) water depths. Younger crabs tend to live in shallower areas with warmer temperatures.
Male and female spider crabs range from dark orange to tan and are known for having long spider-like legs. Females have smaller, wider abdomens than the males. Additionally, the female chelipeds (claw bearing legs) tend to be shorter than the males. Due to their long limbs and poor joints they are often found with missing legs.
Range mass: 16 to 20 kilograms (35.24 to 44.05 pounds) Range length: 3.7 meters (12.14 feet) Average length: 3 meters (9.84 feet)
Giant spider crabs are omnivorous scavengers, eating both plant and animal matter. They don’t hunt their food like most animals, instead, they scurry along the floor and pick up mollusks like clams and mussels as well as dead or decaying organisms. They occasionally eat kelp and algae if it is found.
These crabs mate once a year in early spring (January to March) at the depth of 50 meters (164.04 feet). During their mating season, it is illegal to catch spider crabs in Japan. Though not much is known about their breeding ritual, it is known that they move to shallower waters where the females and males meet, and the male delivers spermatophores into the female’s abdomen. The female can lay up to 1.5 million eggs but only a few will survive. She will carry the eggs on her back until they hatch. Once their eggs hatch, crab larvae receive no parental care.
These crabs are placid animals who remain calm and are not easily upset. They spend the majority of their time scavenging for food. Many juvenile spider crabs decorate themselves for camouflage using their chelae (claws); the crabs tear up objects and attach them to the hooked barbs on their rostrum and carapace. When they mate, they migrate to shallower waters of 50 meters (164.04 feet).
They have a hard, armored exoskeleton that helps protect them from large predators like octopuses. Despite their large size, spider crabs are able to camouflage with their surroundings. They blend their body parts in with the rocky habitat or decorate their shells with sponges and other detritus accessible to them. Spider crabs are able to survive with many legs missing, and they can regrow them over time with successive molts.
Little is known about their longevity, but it is often reported that they can live from 50—100 years in their natural environment.
Conservation efforts focus on preventing overfishing of these crabs. It is illegal to catch them during mating season.