Head to head
Spiny Spider Crab vs Japanese Spider Crab
Spiny Spider Crab
VS Japanese Spider Crab
The spiny spider crab of the north-eastern Atlantic and the Japanese spider crab of the Pacific are both spider crabs that dress themselves in living decorations, but one is a coastal crab and the other a deep-sea giant.
| Spiny Spider Crab | Japanese Spider Crab | |
|---|---|---|
| Scientific name | Maja brachydactyla | Macrocheira kaempferi |
| Relationship | A spider crab, with long, slender legs | A spider crab, and the largest living arthropod by leg span |
| Size | A shell up to about 20 cm across, with a leg span that can exceed half a metre | A carapace up to about 40 cm wide, a leg span up to 3.7 m, and a weight up to about 19 kg |
| Range | Rocky ground, weed, and sandy seabeds of the north-eastern Atlantic, from the British Isles to West Africa | The deep continental slope and outer shelf around Japan, especially off the Pacific coast of Honshu |
| Decoration | Has a pear-shaped, spiny, orange-red shell, often covered with seaweed, sponges, and other living things | Attaches sponges, anemones, and kelp to its shell as a decorator crab |
| Depth | Shallow water close to the coast | Usually 150 to 300 m, recorded from 50 m down to 600 m |
| Gatherings and life | Large numbers gather in piles in shallow water to moult and mate | Possibly up to 100 years, one of the longest-lived crustaceans, and soft and vulnerable for days after each moult |
| Conservation status | Not Evaluated, with local fisheries managed by size limits | Least Concern, on the deep continental slope around Japan |
Spiny Spider Crab vs Japanese Spider Crab: common questions
Which spider crab is bigger?
The Japanese spider crab, with a leg span of up to 3.7 m, the largest of any living arthropod, while the spiny spider crab has a shell of about 20 cm.
Why do spider crabs gather in piles?
Large numbers of spiny spider crabs gather in shallow water to moult and mate, which helps to protect their soft new shells until they harden.
Do both decorate their shells?
Yes, both attach living things such as seaweed, sponges, and anemones to their shells for camouflage.