Pal Hermansen / Close up of Goshawk (Accipiter gentilis) feathers, with one foot held up, Trondelag, Norway. Winner of the Attention to Detail Category of the Bird Photographer Competition 2019.

John Chan / Crenulated fiddler crab (Uca crenulata) waving its major claw at another crab, part of a courtship display, Southern California, USA, June.

John Chan / Crenulated fiddler crab (Uca crenulata) feeding on detritus, Southern California, USA, June.

Georgette Douwma / Boxer Crab (Lybia tessellata) with sea anemones in its claws for defense. Lembeh Strait, North Sulawesi, Indonesia.

Guy Edwardes / African fish eagle (Haliaeetus vocifer), Savuti, Botswana.

David Fleetham / Hawaiian pom-pom / boxer crab (Lybia edmondsoni)with anemones (Triactis sp) that it carries around holding with the claws and using them for defense, waving in front of the possible aggressor. An exam...

Tui De Roy / Galapagos hawk (Buteo galapagoensis) landing, Galapagos, Ecuador. Vulnerable species.

Ingo Arndt / Blue Crab (Discoplax hirtipes) with claws raised in defensive / aggressive posture, endemic to Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Blue Crab (Discoplax hirtipes) with claws raised in defensive / aggressive posture, endemic to Christmas Island, Indian Ocean, Australian Territory

Ingo Arndt / Close up of foot of Hen harrier {Circus cyaneus}

Ingo Arndt / Close up of foot of European mole {Talpa europaea}

Ingo Arndt / Close up of claw of Northern lobster {Homarus americanus}