Purple Shore Crab: a two-minute wildlife lesson

Crabs and Shells · day 7 of 7

Five facts

1. Unlike many shore crabs, this one is a slowcoach. Rather than dash away, it will often stay still and play dead.
2. It can stay out of the water for up to 8 hours. Before climbing out, it breathes extra fast to load up on oxygen.
3. Disturb one and males and females react differently: males often stand and fight, while females drop a leg on purpose and escape.
4. Beaches now hold lots of litter, but given the choice it avoids hiding under plastic, glass or foam and picks natural shelters.
5. Its white-tipped claws are dotted with purple or red spots. A look-alike, the lined shore crab, has no spots on its claws.

The quiz

1. What does the purple shore crab often do instead of running away?

• It plays dead (correct)
• It digs a burrow
• It squirts ink
• It puffs up

It is slow moving and often stays still to play dead.

2. How long can it stay out of the water?

• It can never leave the water
• Up to 5 minutes
• Up to 3 weeks
• Up to 8 hours (correct)

It can spend up to 8 hours out of water after breathing fast first.

3. What do females often do when disturbed?

• Pinch hard and hold on
• Drop a leg and escape (correct)
• Change colour
• Bury themselves in mud

Females shed a leg on purpose and flee, while males tend to fight.

4. Which shelters does it prefer when it can choose?

• Plastic bottles
• Broken glass
• Natural shelters (correct)
• Foam blocks

It tends to avoid plastic, glass and foam and choose natural shelters.

5. How can you tell it apart from the lined shore crab?

• It has a longer tail
• It has spots on its claws (correct)
• It has eight claws
• It has no eyes

Its claws have purple or red spots; the lined shore crab's do not.

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