Deep dive 3 min read
Japanese Spider Crab Size: How Big Is the Largest Crab?
Legs wide enough to hug a small car, a body the size of a dinner plate. The Japanese spider crab is the leggiest giant in the sea. Here's how big it really gets.
If you’ve ever seen a photo of a fisherman holding up a crab with legs longer than he is tall, you’ve met the Japanese spider crab. It’s the crab version of a basketball player: not the heaviest in the sea, but with the longest reach of any animal of its kind. So how big is the largest crab in the world?
The numbers
| Japanese spider crab | |
|---|---|
| Leg span (claw to claw) | Up to about 3.7 m |
| Body (shell) width | Up to about 40 cm |
| Weight | Up to about 19 kg |
| Lifespan | Possibly up to 100 years |
Mostly legs
A Japanese spider crab’s body is only about the size of a large dinner plate. Everything else is legs. With its front legs stretched out, the biggest males measure up to about 3.7 metres from claw to claw. That’s wider than a family car. No other arthropod, the group that includes crabs, insects and spiders, has a longer leg span.
Its body would fit on a dinner plate. Its legs wouldn’t fit in your living room.
Is it the biggest crab?
By leg span, absolutely. By weight, it has rivals. The Tasmanian giant crab has a smaller span but a heavier, chunkier body, and the American lobster holds the weight record among crustaceans with an animal of around 20 kg. On land, the coconut crab is the heaviest crab-like creature. But if you’re asking which crab looks the most gigantic, nothing beats the Japanese spider crab.
Where does it live?
Japanese spider crabs live in the Pacific waters around Japan, usually between about 50 and 600 metres deep. In spring, they move into shallower water to mate and lay eggs. Fishermen in Japan catch them as a delicacy, but there are rules to protect them during the breeding season.
Strange but trueJapanese spider crabs decorate their shells with sponges, seaweed and other living things to camouflage themselves. They’re the ocean’s best-dressed giants.
Long legs, fragile legs
Those long, spindly legs aren’t as strong as they look. Japanese spider crabs are slow, careful walkers and often lose a leg or two. Luckily, they can regrow lost limbs over several moults, although it takes time. They’re scavengers that pick at dead fish and shellfish on the sea floor, using their claws like long tweezers.
Are they dangerous?
They look like something from a nightmare, but Japanese spider crabs are gentle and slow. Their claws can give you a pinch, but they’re not aggressive. Some people call them the gentle giants of the deep. Meet more record-breakers in our Giants collection.
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