Paul D Stewart / Illustration of trilobuite (Paradoxides bohemicus), Plate 1. From 'Organization of the Trilobites' by Hermann Burmeister, appearing in the Ray Society translation of his work published in 1846. The Il...

Paul Williams / Giant water lily (Victoria cruziana) underside of leaf showing spines for protection against fish, and thick stems filled with air for support to float on water, Pantanal, Matogrossense National Park,...

Christophe Courteau / Mountain gorilla (Gorilla beringei) close up showing foot with the gap between the toes, Volcanoes National Park, Rwanda

Alex Mustard / 2020VISION / A stand of Thongweed / spaghetti seaweed (Himanthalia elongata) in evening light, this common seaweed has a two stage morphology, seen here is the strap-like reproductive frond, which can reach up to...

Roland Seitre / Close up of Pacarana (Dinomys branckii) teeth, showing typical rodent morphology. Member of a breeding project. Captive. Biopark reserve, Cota, Bogota, Colombia, January 2010.

Roland Seitre / Close up of Pacarana (Dinomys branckii) teeth, showing typical rodent morphology. Member of a breeding project. Captive. Biopark reserve, Cota, Bogota, Colombia, January 2010.

Sue Daly / Common Cuttlefish (Sepia officinalis) head with unusual eye morphology. Channel Islands, UK, August.

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) males in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) females in breeding coloration and morphology, Kamchatka, Russia, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) and Pink Salmon (Oncorhynchus gorbuscha) in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) female and male in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) male in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) male in breeding coloration and morphology, Kamchatka, Russia

Mark Moffett / Ant (Acanthomyrmex sp) pair showing difference in size and morphology, Tangkoko Nature Reserve, Indonesia

Mark Moffett / Ant (Acanthomyrmex sp) pair showing differences in size and morphology, Tangkoko Nature Reserve, Indonesia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) males and females in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) male and Pink Salmon (Oncorhynchus gorbuscha) males in breeding coloration and morphology, with other juvenile salmonids swimming close by, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) males and females in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) males and Pink Salmon (Oncorhynchus gorbuscha) male in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) male and females as well as a Pink Salmon (Oncorhynchus gorbuscha) male in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) male in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Pink Salmon (Oncorhynchus gorbuscha) male and Sockeye Salmon (Oncorhynchus nerka) males in breeding coloration and morphology, Kamchatka, Russia

Sergey Gorshkov / Sockeye Salmon (Oncorhynchus nerka) male in breeding coloration and morphology, Kamchatka, Russia

Kim Taylor / Termite workers with two nasute soldiers, Trinidad. South America

Juergen Freund / Sea snail {Hexaplex cichoreum} shell specimen, Philippines

Richard Du Toit / African elephant {Loxodonta africana}. Close-up of trunk expelling water. Botswana.

Paul D Stewart / Illustration of Trilobite (Phacops latifrons) enrolled and open, from 'Organization of the Trilobites' by Hermann Burmeister, appearing in the Ray Society translation of his work published in 1846. Th...

Paul D Stewart / Trilobite (Asaphus platycephalus) from 'Organization of the Trilobites' by Hermann Burmeister, appearing in the Ray Society translation of his work published in 1846. The Illustrations and engravings...

Paul D Stewart / Illustration of Trilobite (Homalonotus armatus) from 'Organization of the Trilobites' by Hermann Burmeister, appearing in the Ray Society translation of his work published in 1846. The illustrations a...