When you look at the ling, spiny legs of a daddy long leg spider, does it send chills down your spine? Maybe it’s the beady eyes, the sinewy body type, of just the concept of a spider in general. Thankfully, daddy long leg spiders are relatively small, especially in comparison to a human. Now, picture if a spider with a leg span of over 10 feet, or the height of a single-story building. That sounds impossible, right? While thankfully there are no current land creatures fitting this description, the underwater Giant Japanese Spider Crab boast a leg span of 12+ feet, a body size of 15 inches, and can weigh as much as 45 pounds (or the average young child).
The Japanese spider crab, Macrocheira kaempferi, is in fact named for its resemblance to spiders. Like most other crabs, it features a mainly orange and white coloration pattern. Its eye stalks rest upon the front carapace with thin sensory spines extruding between the eye bases. Finally, their powerful claws grow longer than other limbs, allowing greater power and utility. Unlike most other underwater crustaceous species, males are larger than females (Tracyn).
With such powerful and long legs, it is no surprise that Japanese spider crabs are able to move extremely quickly while stalking prey. However, despite their skill and threatening figure, the crabs are relatively calm and peaceful creatures. Their omnivorous diet mainly consists of shellfish and dead fish, and they only actively hunt when necessary. They most frequently use their strong pinchers to catch and tear meet from algae, plants, mollusks and small fish, but will also use defensively when threatened by humans or predators (Tracyn). Due to their immense size and thick shells, Japanese spider crabs have few predators and consequently, have relatively poor sensory perception.
As thick-shelled crustaceans, they can endure immense pressures without consequences. Preferring depths of 350–1000 feet, Japanese spider crabs migrate to shallower (150 feet) water for spawning (Tracyn). They inhabit the sandy and rocky bottoms in the Pacific Ocean surrounding Japan and are generally considered a sign of good luck among locals. Despite their threatening appearance and disconcerting size, Japanese spider crabs are the underwater gentle giant and deserve our continued respect.
Tracyn. “Japanese Spider Crab.” The Dallas World Aquarium, Dallas World Aquarium, 2020, dwazoo.com/animal/japanese-spider-crab/.
I personally do not like spiders. Especially daddy long legs, they creep me out. So seeing the Japanese Spider as a daddy long legs spider under water, not to mention it has claws… no thank you. Just saying that its the size of a child with claws is terrifying.
I have actually seen a Japanese Spider crab however it was in a tank rather than its natural habitat. In Japan seafood restaurants often have models of them outside, I thought that they can’t actually be that big but seeing one in person it struck me that they really are huge.
It’s interesting that the Japanese Spider Crab is considered a sign of good luck among locals, I wonder how that originated. This is yet just another creature that fascinates me, usually when I think of a crab I picture it to be relatively small, but the Japanese Spider Crab is quite the exception!