Identify a member of the phylum Porifera.

Classify the phylum Vertebrata into their further groups by giving two characteristics of each.

Which one is a true fish?

$(a)$ In which two ways do amphibians differ from fishes?
$(b)$ Identify the phylum of organisms having the following characteristics:
$(i)$ Pore-bearing animals and radial symmetry.
$(ii)$ Body spiny and radial symmetry.
$(c)$ Why do gymnosperms not require water for fertilization?

In which group of animals,the coelom is filled with blood?

What is a notochord? What is its function?