They all develop through an embryo that is enclosed within a membrane called an amnion. The amnion surrounds the embryo with a watery substance, and is probably an adaptation for breeding on land. This marine iguana for instance spends much of its time on the sea shore and lays its eggs on land.

Do lizards have amnion?

Reptile are amniotes that lay their eggs on land; they have scales or scutes and are ectothermic. ... Squamata, the largest group of reptiles, includes the lizards and snakes.

Do amphibian eggs have amnion?

Amphibians are four-legged animals that don't have amniotic eggs. Amniotic eggs have a membrane called the amnion. The amnion is a fluid-filled sac where the embryo develops. ... Because amphibian eggs don't have an amnion, the eggs would dry out if they were laid on the land, so amphibians lay their eggs in water.