Mark Moffett / Army Ant (Eciton sp) workers of different sizes carrying pupa while migrating, Barro Colorado Island, Panama

Mark Moffett / Army Ant (Eciton sp) workers of different sizes carrying pupa while migrating, Barro Colorado Island, Panama

Jane Burton / Fawn Pug pup sitting between fawn English Mastiff pups.

Petra Wegner / Domestic dogs, five Cavalier King Charles Spaniel puppies, 7 weeks old, in basket. Note their different colours and sizes.

Petra Wegner / Domestic dogs, four Cavalier King Charles Spaniel puppies, 7 weeks old, of different sizes and colours

Petra Wegner / Domestic dogs, five Cavalier King Charles Spaniel puppies, 7 weeks old of different colours and sizes

Constantinos Petrinos / Wine measuring cups of various sizes outside shop for locally produced wine, Alonissos Island (Aegean) Greece

GEORGETTE DOUWMA / Land hermit crabs of various sizes {Coenobita perlatus} Lakshadweep, India

Mitsuhiko Imamori / Collection of insect specimens showing variety of shapes and sizes, Shiga, Japan

Mark Moffett / Leafcutter Ant (Atta sexdens) comes in a variety of worker sizes, each one has a special function in the society, here one of the smallest workers carries fungus around, planting wherever there is a n...

Claudio Velasquez / King protea flowers {Protea cynaroides} Table Mountain NR, S Africa. Did you know? Proteas are named after the Greek god Proteus who could change his form, as proteas have a diverse range of shapes an...

Paul D Stewart / A group of Darwin's finches, Geospizinae, from the collection of the Charles Darwin Research Station on Galapagos, showing a range of beak sizes and shapes. Darwin originally misidentified the finches...