Nick Upton / Goldenrod crab spider (Misumena vatia) female on Field scabious (Knautia arvensis) waiting for prey to land, legs raised, Wiltshire, England, UK. July.

Kevin Schafer / Purple Land Crab (Gecarcinus ruricola) juvenile, Zapata Peninsula, Cuba

Charlie Summers / Cocos Purple Land Crab (Cardisoma carnifex) in defensive position. Cocos-Keeling Island, Indian Ocean, Australia, May.

Pete Oxford / Purple Claw Land Hermit (Coenobita clypeatus) on palm trunk, Sian Ka'an Biosphere Reserve, Quintana Roo, Mexico

Mark Bowler / Purple pincher / Purple claw land hermit crab {Coenobita clypeatus} investigating a new shell, a tropical rainforest land crab from the Caribbean.

Mark Bowler / Purple pincher / Purple claw land hermit crab {Coenobita clypeatus} a tropical rainforest land crab from the Caribbean. Sequence showing crab emerging from shell. Digital composite

Mark Bowler / Purple pincher / Purple claw land hermit crab {Coenobita clypeatus} a tropical rainforest land crab from the Caribbean. Sequence showing crab emerging from shell. Digital composite

Mark Bowler / Purple pincher / Purple claw land hermit crab {Coenobita clypeatus} a tropical rainforest land crab from the Caribbean. Sequence showing crab emerging from shell. Digital composite

Luciano Candisani / Yellow and Purple Land Crab (Gecarcinus lagostoma) in defensive position, Rocas Atoll, Brazil

Luciano Candisani / Yellow and Purple Land Crab (Gecarcinus lagostoma) walking on the beach at night, Rocas Atoll, Brazil

Piotr Naskrecki / Black Land Crab (Gecarcinus ruricola) bright coloration combined with a pair of powerful claws make for a convincing threat display, Costa Rica

Phil Chapman / Scarlet land hermit crab. (Coenobita sp) Henderson Island. These crabs specialise in beach life, avoiding conflict with the primary forest-dwelling giant purple land hermit crabs

Phil Chapman / Giant Purple land hermit crab, Henderson Island. Favourite food is the oily nuts of Pandanus screw palms

Kevin Schafer / Purple Land Crab (Gecarcinus ruricola) in intertidal zone, Zapata Peninsula, Cuba

Kevin Schafer / Purple Land Crab (Gecarcinus ruricola), Zapata Peninsula, Cuba

Phil Chapman / Giant Purple land hermit crab. (Coenobita sp) Herson Island Favourite food is the oily nuts

Bernard Castelein / Madagascan land crab (Madagapotamon humberti) portrait, Ankarana National Park, Madagascar.

Bernard Castelein / Madagascan land crab (Madagapotamon humberti) portrait, Ankarana National Park, Madagascar.

Staffan Widstrand / Wild Wonders of China / Violet land crab (Geograpsus grayi) SanXianTai/ San-Hsien-T'ai Island, Chenggong township, Taiwan

Staffan Widstrand / Wild Wonders of China / Violet land crab (Geograpsus grayi) SanXianTai/ San-Hsien-T'ai Island, Chenggong township, Taiwan