2006-12-05 09:19:17 · 3 answers · asked by Kayllen M 1 in Science & Mathematics ➔ Biology
Well, for reptiles and birds, the reason why they can reproduce on dry land is the amniotic egg. The amniotic egg can survive in dry places cause there isn't a risk of it drying out due to the outer membrane, all the moisture is retained inside the egg. With amphibians and fish, they can't reproduce on land because they lack this membrane and will dry out unless there is someway to keep it moist. Mammals can reproduce on dry land because the embryo develops inside the body (a few exceptions). Plus, reptiles, birds, and mammals retain moisture within the body. Amphibians, in most cases, need moisture to stay alive and if they wonder to far from water they could die.
2006-12-05 09:51:39 · answer #1 · answered by DWare5883 2 · 1⤊ 0⤋
Reptiles and birds have evolved the ability to produce a tough cover for their eggs that allow them to be exposed to air without drying out or being attacked by bacteria or molds. Some reptiles are live bearers, meaning they carry their young internally and give birth to live young. A very few mammals are monotremes, which lay reptilian-like eggs. Most are marsupials or placentals that give birth to air-breathing live young after a period of maturing, either in a pouch (marsupials) or in a uterus (placentals).
2006-12-05 10:09:24 · answer #2 · answered by Jerry P 6 · 0⤊ 0⤋
Yeah, that's very... Disturbing.
2006-12-05 09:27:13 · answer #3 · answered by Anonymously Anonymous 5 · 0⤊ 0⤋