Amniota: Quick Facts

Written and fact-checked by

The Information Architects of Encyclopaedia Britannica

Facts

Also Known As	amniote

Photos

Labeled diagram of an amniotic egg showing the embryo surrounded by membranes including the amnion, chorion, yolk sac, and allantois, with albumin, amniotic fluid, yolk, and shell also identified.

Labeled diagram of an animal egg cut in half, showing structural components including the outer shell layers, inner and outer membranes, yolk with its membrane and germinal disc, and albumen with thick and thin egg white, chalaza, and chalaziferous layer.

Diagram of the tree of life based on the three-domain system, showing Archaea, Bacteria, and Eukaryota branching into four kingdoms: Plants, Animals, Fungi, and Protista, with illustrations of representative organisms for each group.

See All Images →

Topics

reptile Bird mammal Vertebrate fish tetrapod chondrichthyan amphibian agnathan 5 Vertebrate Groups 10 Animals With Evolutionary Traits Plucked Straight Out of a Nightmare Tiktaalik roseae How old is the oldest living Greenland shark?placoderm

The bearded vulture (Gypaetus barbatus) is seen in Switzerland on December 2024

Animal Factoids

Lion (panthera leo)

Deadliest Animals Quiz

Young chimpanzee dressed in a shirt and sweater vest, scratching his head thinking. (primates)

Wild Words from the Animal Kingdom Vocabulary Quiz

Mute swan with cygnet. (birds)

Match the Baby Animal to Its Mama Quiz

Sea otter (Enhydra lutris), also called great sea otter, rare, completely marine otter of the northern Pacific, usually found in kelp beds. Floats on back. Looks like sea otter laughing. saltwater otters

Animal Group Names