Question

why birds are called amniotes?

Answer 1

Hey friend, Harish here.

Here is your answer:

All birds lay amniotic eggs. Hence they are know as amniote.

→ These amniotic eggs have tough outer covering to protect the eggs from outer harmful environment.

→ Not only Birds , but few other reptiles and also mammals which lays amniotic eggs are known as amniote.
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Hope my answer is helpful to you. 

Answer 2

Answer:

Birds are called amniotes because they lay amniotic egg with an amnion.

Whqt are Amniotes?

• A group of tetrapod vertebrates known as amniotes includes mammals, birds, and reptiles.
• An egg with an amnion, an adaption to lay eggs on land or keep the fertilised egg inside the mother, is what distinguishes amniotes from other species.
• Whether implanted as eggs or carried by the female, amniotic embryos are shielded and helped by a number of thick membranes. These membranes cover the amniotic sac, which envelops the developing foetus in eutherian mammals (including humans).
• The absence of a larval stage and these embryonic membranes set amniotes apart from tetrapod amphibians.
• The terrestrially adapted egg of the amniotes, which include reptiles, birds, and mammals, is what sets them apart from amphibians. 
• The creation of amniotic membranes allowed amniotes to branch out into drier habitats since their embryos had access to their own aquatic environment, which reduced their reliance on water for growth. 
• This was a crucial advancement that set them apart from amphibians, whose eggs lacked a shell and forced them to live only in damp settings. 
• Although the shells of different amniotic species vary greatly, they are all capable of holding water.
• The calcium carbonate makes up a bird egg's strong but brittle shell.
• Reptile eggs have leathery shells and need a damp environment to hatch.
•  Most mammals don't produce eggs (except for monotremes).Instead, the embryo develops inside the mother's body; nonetheless, amniotic membranes are still present throughout this internal gestation.

Characterstics of  Amniotic egg.

• The amniotic egg is the primary distinguishing feature of amniotes. 
• In amniotes that lay eggs, the egg shell protects the growing embryo while being sufficiently transparent to permit the exchange of carbon dioxide and oxygen. 
• As with the eggs of many other animals, such as frogs, the albumin, or egg white, gives the embryo water and protein, while the yolk, which is fatter, serves as the embryo's energy source.
• The chorion, amnion, and allantois are three additional extra-embryonic membranes found in the eggs of amniotes.
• Membranes found in amniotic eggs but not a component of the developing embryo's body are known as extra-embryonic membranes.
• The chorion encloses the embryo and yolk sac, whereas the inner amniotic membrane only encloses the embryo itself.
• The chorion aids in the exchange of oxygen and carbon dioxide between the egg's environment and the developing embryo.
• The amnion aids in hydration and shields the embryo from mechanical trauma.
• The allantois both aids breathing and accumulates nitrogenous wastes generated by the embryo. The placenta of mammals contains membranes that resemble the extra-embryonic membranes found in eggs.

To learn about Characteristic features of reptiles click here-

https://brainly.in/question/3344711

To learn about Amniotic sac click here-

https://brainly.in/question/914218