Identify a member of the phylum Porifera.

Differentiate between the following:
$(a)$ Tube system of feather star and canal system of $Euplectella$
$(b)$ Skeleton of shark and sea horse
$(c)$ Respiratory organs of tadpole and frog
$(d)$ Forelimbs of birds and lizard
$(e)$ Skin of tree frog and human

Thallophyta,Bryophyta and Pteridophyta are classified as Cryptogamae,whereas Gymnosperms and Angiosperms are classified as Phanerogamae. Why?

The locomotory organs of $Echinodermata$ are:

Which among the following is exclusively marine?

Echinoderms have a system that they use for moving around. Name the system. What is their skeleton made-up of?