Eric Baccega / Chimpanzee (Pan troglodytes) female aged 37 years, portrait. Beauval Zoo Parc, France. Captive.

Frederique Olivier / Emperor penguin (Aptenodytes forsteri) chicks flapping wings to strengthen muscles, Adelie Land, Antarctica, January.

Frederique Olivier / Panning shot of Emperor penguin (Aptenodytes forsteri) chicks flapping wings, strengthening muscles, Adelie Land, Antarctica, January.

Floris van Breugel / High speed exposure of a Fruit fly (Drosophila melanogaster) taken through a microscope. In this image flight muscles express a genetically engineered protein called GCaMP, which fluoresces green in t...

Floris van Breugel / Fruit fly (Drosophila melanogaster) tethered in LED illuminated chamber which stimulates moving visual patterns. Behind the fly is a camera, which is used to record its wing beat amplitude a rough me...

Christian Ziegler / Leaf-nosed Bat (Phyllostomidae) flight muscles and blood vessels in the wing membrane, Smithsonian Tropical Research Station, Barro Colorado Island, Panama

Mark Moffett / Leafcutter Ant (Atta sexdens) soldier, close-up, the largest worker in many leafcutter colonies specialize in defense, their enlarged heads contain massive adductor muscles to work their powerful jaws...

Christian Ziegler / Leaf-nosed Bat (Phyllostomidae) flight muscles and blood vessels in the wing membrane, Smithsonian Tropical Research Station, Barro Colorado Island, Panama

Robin Chittenden / Peregrine falcon (Falco peregrinus) strengthening muscles by flapping its wings, Norwich Cathedral UK, June.

Stephen Dalton / Poplar Hawk (Laothoe populi) warming wing muscles Sussex, England, UK.

Ingo Arndt / Thermal imaging of Honey bee (Apis mellifera) brood comb. Cooler parts appear darker, warmer parts appear bright in colour. Very bright spots showing worker bees heating brood cells with the help of t...

Ingo Arndt / Thermal imaging of Honey bee (Apis mellifera) brood comb. Cooler parts appear darker, warmer parts appear bright in colour. Very bright spots showing worker bees heating brood cells with the help of t...