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

Pascal Kobeh / Corallimorph decorator crab (Cyclocoeloma tuberculata), Sulu sea, Philippines

David Fleetham / Decorator crab (Cyclocoeloma tuberculata) covered with Hydroids (Hydrozoa) to ward off predators. Off Rinca Island and Komodo Island, Indonesia.

Olga Kamenskaya / Great spider crab (Hyas araneus) Novaya Zemlya, Russian Arctic, July

Olga Kamenskaya / Great spider crab (Hyas araneus) Novaya Zemlya, Russian Arctic, July

Olga Kamenskaya / Great spider crab (Hyas araneus) Novaya Zemlya, Russian Arctic, July

Olga Kamenskaya / Great spider crab (Hyas araneus) Svalbard, Norway, September.

Constantinos Petrinos / Corallimorph decorator crab (Cyclocoeloma tuberculata) Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Corallimorph decorator crab (Cyclocoeloma tuberculata) fixing Corallimorpharian (Discosomatidae) to shell using setae, Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Corallimorph decorator crab (Cyclocoeloma tuberculata) fixing Corallimorpharian (Discosomatidae) to shell using setae, Lembeh Strait, North Sulawesi, Indonesia.

Pascal Kobeh / Slender / Graceful decorated crab (Oregonia gracilis), Alaska, USA, Gulf of Alaska. Pacific ocean.

Jack Perks / European spider crab (Hyas araneus) entering frame, stopping to feed on seabed before walking off into Common eelgrass (Zostera marina), Swanage pier, Dorset, England, UK, English Channel, September.