John Shaw / Sally lightfoot crabs (Grapsus grapsus) on the beach at Puerto Egas, Santiago Island, Galapagos, May.

Robin Chittenden / River crab (Potamon potamios) on sand. Cyprus. April.

Emanuele Biggi / Freshwater crab (Potamon fluviatile) living in old Roman ruins, Traiano's Market, Rome, Italy

Emanuele Biggi / Freshwater crab (Potamon fluviatile), mating pair, Italy, September.

Emanuele Biggi / Freshwater crab (Potamon fluviatile), adult female on stream bed at the entrance of her burrow, Italy. August.

Emanuele Biggi / Freshwater crab (Potamon fluviatile) adult female on stream bed at the entrance of her burrow, Italy. August 2012.

Emanuele Biggi / Freshwater crab (Potamon fluviatile), adult male at the entrance of its burrow, Tuscany, Italy, August.

Emanuele Biggi / Freshwater Crab (Potamon fluviatile), young carried in their mother's telson pouch, Tuscany, Italy. August.

Chris Mattison / Tree-climbing land crab (Malagasya antongilensis) Nosy Mangabe, Madagascar.

Piotr Naskrecki / Crab (Potamonautidae), Gorongosa National Park, Mozambique

MYN / Emanuele Biggi / Freshwater crab (Potamon fluviatile) juvenile, Tuscany, Italy, March. Meetyourneighbours.net project

MYN / Emanuele Biggi / Freshwater crab (Potamon fluviatile) juvenile,Tuscany, Italy, March. Meetyourneighbours.net project