Write two characteristic features of the phylum to which Ascaris belongs. Name the parasitic worm that causes elephantiasis.

State the importance of classification.

Give the differences between bony and cartilaginous fish.

Give the main features of chordates.

Which among the following have scales?
$(i)$ Amphibians
$(ii)$ Pisces
$(iii)$ Reptiles
$(iv)$ Mammals

Name the phylum to which the following organisms belong:
$(a)$ Organisms which have a peculiar water-driven tube system that they use for moving around.
$(b)$ Organisms which have a foot that is used for moving around and have an open circulatory system.
$(c)$ These organisms have holes or pores all over the body. These lead to a canal system that helps in circulating water throughout the body.