Horseshoe Crab
Limulus polyphemus
A 'living fossil' older than the dinosaurs, more closely related to spiders than crabs, with blue blood.
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About the Horseshoe Crab
Horseshoe crabs can reach 2 feet long, including the tail, and take about 10 years to grow up. Despite the name, they are more closely related to spiders and scorpions than to crabs. They live in shallow coastal waters with sandy or muddy bottoms along the Atlantic coast from Mexico's Yucatán to Maine. They eat worms, crustaceans, small mollusks and algae.[1]
Quick facts
- Scientific name
- Limulus polyphemus[1]
- Size
- Up to 2 feet long, including the tail.[1]
- Lifespan
- 20 years or more in the wild.[1]
- Diet
- Worms, crustaceans, small mollusks and algae.[1]
- Habitat
- Shallow coastal waters with sandy or muddy bottoms.[1]
- Where it lives
- Atlantic coast of North America, from the Yucatán Peninsula to the Gulf of Maine.[1]
- Group life
- Solitary except when breeding. Feeds at night.[1]
- Babies
- Up to 100,000 eggs a season; young molt up to 16 times.[1]
- Conservation status
- Vulnerable (IUCN Red List, assessed 2016).[2]
Fun facts
Vocabulary
- living fossil
- A living species that has changed very little over millions of years.
- exoskeleton
- A hard outer covering that supports and protects an animal's body.
- arachnid
- An animal with eight legs and two body parts, such as a spider or scorpion.
- molt
- To shed an old outer covering, like skin or feathers, and grow a new one.
- vulnerable
- A conservation label meaning a species faces a high risk of dying out in the wild.
See it in person
- Smithsonian's National ZooWashington, D.C. · Bird HouseSee this animal on the zoo's website ↗
These zoos had this animal when we gathered our information, but animals sometimes move. Check the zoo's website or contact the zoo before you visit.
Sources
- [1] Smithsonian's National Zoo & Conservation Biology Institute. “Horseshoe crab.” https://nationalzoo.si.edu/animals/horseshoe-crab (accessed 2026-10-08)
- [2] IUCN Red List of Threatened Species. “Limulus polyphemus (American Horseshoe Crab).” https://www.iucnredlist.org/species/11987/80159830 (accessed 2026-10-08)
Facts last checked 2026-10-08.
