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How do birds develop without a placenta?
Placenta is used by certain mammals to nurture embryos that will develop into a baby that will be born live. Birds, however, don't give birth to live young. Instead, they lay eggs, and the embryo inside the egg is nurtured by a nutrient and energy rich yolk sac, rather than by a placenta.
How do animals develop without a placenta?
Animals that do not develop in a placenta will develop outside of the uterus rather than in. Kangaroos and Koalas use pouches to develop their young.
How do tadpoles develop without a placenta that links them to its mothers blood supply?
They develop by feeding from the yolk of the egg that the frog has laid and that is the equivalent of a placenta.
Do twins share a placenta during pregnancy?
Yes, twins can share a placenta during pregnancy. This occurs when identical twins develop from a single fertilized egg and share the same placenta.
Why can't humans lay eggs?
Humans are placental mammals, meaning that they develop with the embryo attached to a placenta that allows it to exchange waste and nutrients with the mother. The placenta would not be able to function inside an egg.
Where do most mammals grow before they're born?
Most mammals are placental mammals: they develop in a placenta before birth. Marsupials also develop in a placenta, but they are delivered much earlier and the placenta is less developed. Monotremes develop within an egg, which is kept inside the mother for some time before it is laid. It hatches several days later.
Do mammals develop in egg or in uterus?
Placental mammals and marsupials develop in a placenta within the uterus before being delivered. Monotremes develop in an egg.
How do placentals young develop?
The young of placental mammals develop within a placenta. The placenta is a thick membrane that is connected to the inside of the uterine wall. The umbilical cord connects the baby to the inside wall of the placenta. Nutrients and oxygen go from the mother's blood stream through the placenta, down the umbilical cord, and into the baby. The baby releases waste products and carbon dioxide, which travel up the umbilical cord, through the placenta and into the mother's blood stream.
Do birds develop externally or internally?
Birds develop internally, which means inside the creatures body.
Tadpoles and birds are examples of animals that develop without a placenta that links them to the mothers blood suply explain how these organisims develop?
The same way every animal before mammals evolved did it. The egg contains a yolk loaded with nutrients that they live off and the shell has pores that let air in and carbon dioxide out for their respiration.
How did placental mammals develop from birds?
They did not. Mammals evolved independently of birds.
Why do fraternal twins have their own placenta?
Identical twins may or may not share the same placenta . Identical twins develop when a fertilized egg splits. Depending on when the split occurs will determine if the twins share a placenta, with either one or two chorions and amnions, or if they each develop their own placentas.
