An intricate three-dimensional network of blood vessels nourishes the heart.
Many animals have a third eyelid called a nictitating membrane that protects the eye.
The eye of a chimpanzee views the world in living color.
The fins of the scalyhead sculpin are related to our arms.
Tiktaalik roseae, also known as the “fishapod,” is an animal that lived about 375 million years ago, with features of fish and four-legged animals.
The Cape Cliff lizard sports a bony body armor.
The shape of our hands comes from tree-dwelling ancestors.
The bill of the buff-tailed sicklebill hummingbird is perfectly shaped to collect nectar from deep within the Centropogon flower.
Two views of a late pupa of an unidentified midge species (family Chironomidae).
The skull of Zinjanthropus is one of the first early hominid fossils found in Africa and provides essential clues in the story of human evolution.
A reconstruction of Anchiornis huxleyi, a feathered dinosaur that is part of the ancestral lineage of birds.
The muscles of the mouse’s heart contract about 600 times per minute, or a billion times in its three-year lifespan.
A close-up view of the sound-producing structure on the wing of a field cricket (Gryllus pennsylvanicus).