Birds have hollow bones. explain how this is adaptive.

This aquarium exhibits biotic and abiotic factors in an aquatic environment. one of the abiotic factors is

When a person is exercising the body needs to deliver increased amounts of oxygen to the muscles which component of blood ensures that the muscles will receive it

What function does the limb sever in each animal? how are the limb bones of the four animals similar? based on these similarities what can be inferred about the evolution of the four animals.