Question

1. Why are both sponges and corals hardened? What benefit does this give the organisms?

2. Compare and contrast the different morphs in Cnidaria in terms of movement, shape, complexity, etc.

3. Sponges and cnidarians have no lungs or gills. How do they exchange gases with the environment? Are humans better off having lungs? Why/why not?

Answer 1

1. Hardened surface gives them protection from other sea animal or something else.

With their hardened surfaces,corals are sometimes mistaken as being rocks.

2)
Captured prey to the mouth, digestion of food, and expulsion of waste, is Composed of nerve cells scattered across the body.
(3) They exchange gases through diffusion process with environment.

During gas exchange, oxygen from the environment diffuses into the animal through gastrovascular cavity, while carbon-di-oxide is expelled out as a waste product.

Yes,humans are better off having lungs.

Because humans are multicellular organisms and it is difficult to exchange gases with environment through diffusion.