Crabs

All crabs belong to the group called the Decapoda – Latin for ‘ten legs’.

There are lots of crab species in the Gulf, and they range in size from tiny to quite large. Most have hard shell (carapace) unless they are moulting. This happens as the crab is growing. Calcium is reabsorbed from the old shell, which gradually becomes softer, and is used to grow its next shell. When the new shell is ready the old shell is cast off, and the new shell hardens quickly. Sometimes the soft, old shell is washed up. Hermit crabs don’t have a hard carapace, and they use empty marine snail shells to protect their soft bodies. As they grow they need to find larger snail shells. If you are collecting shells on the beach, be sure to check that there is not a hermit crab in residence!

The Blue Swimmer is probably the best known crab, and is sought after because it is abundant and tasty! If you see one in the water while you are swimming, or in a tidal pool, don’t get too close – a nip from their claws is painful.

Sand crab carapace – note the two dark red sots

Sand crabs are pale reddish with two darker spots on the carapace.

 

 

 

 

 

 

 

 

 

Spider crabs range greatly in size, but characteristically have really long legs.

Spider crab near Henley Jetty – approx 20 cm across the carapace

 

 

 

 

 

 

 

 

 

 

Tiny spider crab – approx 1 cm across the carapace

 

 

 

 

 

 

 

 

 

 

 

Rock crabs are smaller and chunkier than the swimmers and spider crabs, but are really good at wedging themselves under rocks and in cracks.

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