The locomotory organs of $Echinodermata$ are:

Label $a, b, c$ and $d$ given in the figure. Give the function of $(b)$.

Classify the following organisms based on the absence/presence of a true coelom (i.e., acoelomate, pseudocoelomate, and coelomate): $Spongilla$, $Sea \text{ } anemone$, $Planaria$, $Liver \text{ } fluke$, $Wuchereria$, $Ascaris$, $Nereis$, $Earthworm$, $Scorpion$, $Birds$, $Fishes$, $Horse$.

Why do we classify both snakes and turtles in the same class?

To which class of Animalia does the housefly belong? Mention any three characteristic features of this class of animals. Give two other examples of this class of animals.

$(a)$ 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?