Morley Read / Close-up of Agua rica leaf frog (Phyllomedusa ecuatoriana) eggs after 11 days development, showing beating heart and blood flowing over gills, Ecuador. Endangered. (non-ex)

Morley Read / Developing embryo of the Ecuadorian monkey frog (Phyllomedusa ecuatoriana), showing heart beating and blood flowing, Morona Santiago Province, Ecuador, (non-ex)

Daniel J. Cox / Gray Wolf (Canis lupus) predating female Elk (Cervus elaphus) crossing river, Alum Creek, Yellowstone National Park, Wyoming, sequence 4 of 4

Daniel J. Cox / Gray Wolf (Canis lupus) killing female Elk (Cervus elaphus) crossing river, Alum Creek, Yellowstone National Park, Wyoming, sequence 3 of 4

Daniel J. Cox / Gray Wolf (Canis lupus) attacking female Elk (Cervus elaphus) crossing river, Alum Creek, Yellowstone National Park, Wyoming, sequence 2 of 4

David Perpinan / Aeroplane flying in front of a total lunar eclipse, also called a Blood Moon, Barcelona, Spain, 27th July 2018.

Agustin Esmoris / Southern Elephant Seal (Mirounga leonina) male calling and bleeding after fight, Puerto Madryn, Argentina

Hans Glader/ BIA / Blood moon, North Rhine-Westphalia, Germany

Espen Bergersen / Gulls (Laridae) seaching for food in water containing blood coming from a large fishing boat, Tromvik, Kvaloya, Troms, Norway, November 2014.

Sam Hobson / Blood samples collected by scientists working with urban goshawks (Accipiter gentilis). Berlin, Germany, May 2014. Nominated in the Melvita Nature Images Awards competition 2014.

Bryan and Cherry Alexander / Chukchi girls, with their family's ancestral clan mark painted in reindeer blood on their face, a ritual during the Chukchi 'Festival of the Young Reindeer' during which young reindeer are sacrificed....

Piotr Naskrecki / Yellow Fever Mosquito (Aedes aegypti) female feeding on human blood, Gorongosa National Park, Mozambique