# Japanese Spider Crab (*Macrocheira kaempferi*)

> The Japanese spider crab (Macrocheira kaempferi) is the world's largest arthropod, with leg spans reaching 3.7 m in deep Pacific waters off Japan. Adults weigh 20 kg and are Least Concern.

- **Category:** Invertebrate
- **Conservation status (IUCN):** Least Concern
- **Range:** Deep waters off Japan.
- **Canonical page:** https://globalanimalguide.org/animals/japanese-spider-crab/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Arthropoda
- **Class:** Malacostraca
- **Order:** Decapoda
- **Family:** Inachidae
- **Genus:** Macrocheira

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Macrocheira kaempferi |
| Diet | Scavenger / carnivore |
| Habitat | Deep continental slopes |
| Lifespan | 50–100 years |
| Weight | 15–20 kg |
| Top speed | up to 3 km/h |
| Conservation status | Least Concern (IUCN) |

## Leg span of a small car

Spindly legs and a relatively small knobby carapace create record arthropod span. Slow metabolism suits cold deep water on continental slopes.

## Scavenger of the deep slope

Dead fish, molluscs, and plant debris are picked from the seabed. Adults migrate seasonally to shallower depths for breeding.

## Deep waters off Japan

Pacific slopes around Honshu and nearby depths of 200–800 m. Larvae develop in plankton before settling to the abyssal fringe.

## Protected giant

Least Concern with fishing restrictions in Japan. Aquarium displays and cultural fame support conservation awareness.

## Frequently asked questions

### How wide is a Japanese spider crab?

Leg span can reach about 3.7 m — the largest known arthropod span.

### Are Japanese spider crabs dangerous?

They are slow deep-water scavengers; claws can pinch but they are not predators of humans.

### Where do Japanese spider crabs live?

Deep Pacific continental slopes primarily around Japan.

### What do Japanese spider crabs eat?

Carrion, molluscs, and plant material scavenged on the seabed.

### Can you eat Japanese spider crab?

Yes — it is a delicacy in Japan under regulated fisheries.

---
Source: Global Animal Guide (https://globalanimalguide.org/animals/japanese-spider-crab/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.