# Largest Crabs on Earth! (DD-190)

> Spider crabs are crabs of the superfamily Majoidea, named for their long, thin legs. The Japanese spider crab (Macrocheira kaempferi) has the largest leg span of any arthropod, up to about 3.7 m. Many spider crabs decorate their shells with sponges, algae and debris for camouflage. In southern Australia, giant spider crabs (Leptomithrax gaimardii) gather in huge aggregations of thousands each year to molt together, which researchers think protects them while their new shells harden. The footage shows spider crab aggregations and Japanese spider crabs, with the presenter.

- Department: Nature
- First published: 2024-01-19
- Last updated: 2024-01-19
- Permalink: https://detailenjoyer.com/case/largest-crabs-on-earth/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-190-F01**: Spider crabs belong to the Majoidea. _(Write-up · Exhibit A (Majoidea))_
- **DD-190-F02**: The Japanese spider crab spans up to about 3.7 m. _(Write-up · Exhibit B (Largest span))_

## Write-up

Japanese spider crabs can span nearly 4 m leg to leg. In Australia, thousands of spider crabs pile up each winter.

1. **Majoidea**: Spider crabs belong to the Majoidea.
2. **Largest span**: The Japanese spider crab spans up to about 3.7 m.
3. **Decorating**: Many decorate their shells for camouflage.
4. **Aggregations**: Australian giant spider crabs gather by the thousands.
5. **Molting together**: They gather to molt.

## Related case files

- [CrabMaxxing (DD-735)](https://detailenjoyer.com/case/crabmaxxing/): I linked more about crabs
- [Long-Living Like Larry (DD-194)](https://detailenjoyer.com/case/long-living-like-larry/): I paired it with another crustacean that grows by molting
- [Imposter Crab (DD-378)](https://detailenjoyer.com/case/imposter-crab/): I linked more crabs

## Reel vs. record

- **Note**: The Reel shows two species: the largest crab is the Japanese spider crab, while the mass gatherings are Australian giant spider crabs, which gather mainly to molt.

## Video: Largest Crabs on Earth!: Japanese Spider Crabs Can Span Nearly 4 m Leg to Leg

- Duration: 33.1 s · Published: 2024-01-19
- File: https://detailenjoyer.com/assets/videos/C2SHBKJOWw8.mp4

### Transcript

Spider Crabs members of the crustacean family are intriguing creatures known for their remarkable appearance in annual mass migrations Did you know they have a peculiar habit of forming large Aggregations during the mating season thousands of spider crabs gather together and migrate in a caravan across the ocean floor What adds to their allure is their distinctive appearance with long spindly legs resembling a spider providing them with excellent camouflage among underwater vegetation this behavior and unique morphology Demonstrates the fascinating adaptations that spider crabs have evolved to thrive in their marine environments. NOW YOU KNOW!

## Questions & answers

**Q: What are spider crabs named for?**  
A: Superfamily Majoidea. _(Source: Write-up · Exhibit A (Majoidea) · Wikipedia: Spider crab)_

**Q: Which crab has the largest leg span?**  
A: Up to about 3.7 m. _(Source: Write-up · Exhibit B (Largest span) · Wikipedia: Japanese spider crab)_

**Q: How do many spider crabs hide?**  
A: Sponges and algae. _(Source: Write-up · Exhibit C (Decorating) · Wikipedia: Spider crab)_

**Q: Where do giant spider crabs aggregate?**  
A: By the thousands. _(Source: Write-up · Exhibit D (Aggregations) · Wikipedia: Leptomithrax gaimardii)_

**Q: Why do they gather?**  
A: Safety in numbers. _(Source: Write-up · Exhibit E (Molting together) · Wikipedia: Leptomithrax gaimardii)_

## Sources

- [Wikipedia: Spider crab](https://en.wikipedia.org/wiki/Spider_crab)
- [Wikipedia: Japanese spider crab](https://en.wikipedia.org/wiki/Japanese_spider_crab)
- [Wikipedia: Leptomithrax gaimardii](https://en.wikipedia.org/wiki/Leptomithrax_gaimardii)

## Cite this case file

Easterling, Marcus. "Largest Crabs on Earth!." The Detail Department (DetailEnjoyer), case file DD-190, last updated Jan 19, 2024. https://detailenjoyer.com/case/largest-crabs-on-earth/