Everything You Need to Know About Crabs

Crabs are among the most recognizable ocean creatures — and one of the most successful. With over 7,000 species found in every ocean and even on land, crabs have been scuttling across the planet for over 200 million years.

Why Do Crabs Walk Sideways?

Crabs walk sideways because of how their leg joints are structured — their legs bend outward rather than forward or backward like ours. Some crabs, like the ghost crab, can actually run forward at speeds up to 10 mph — the fastest land crab on Earth.

How Many Legs Do Crabs Have?

Crabs have 10 legs total — 8 walking legs and 2 front claws (called chelipeds). The claws are used for feeding, defense, and communication (waving at potential mates). Crabs can regrow lost claws and legs over time.

How Big Are Crabs?

The Japanese spider crab is the world's largest crab, with a leg span up to 12 feet — bigger than most people are tall. The smallest is the pea crab at just 0.27 inches, which lives inside oysters and mussels.

Are Crabs Intelligent?

Crabs are more intelligent than most people realize. They can learn from experience, navigate mazes, remember solutions to problems, and even show signs of anxiety. Recent research suggests crabs may experience pain and have more complex inner lives than previously thought.

Amazing Crab Facts

• Crabs communicate by drumming and waving their claws.
• Hermit crabs don't have their own shells — they use abandoned gastropod shells and upgrade to larger ones as they grow.
• The coconut crab is the world's largest land invertebrate and can crack open coconuts with its claws.
• Female crabs can store sperm for up to 2 years before fertilizing their eggs.
• Blue crabs get their blue color from a copper-based pigment in their blood mixed with red proteins.