Identify a member of the phylum Porifera.

Write the most striking features of the following phyla:
$(i)$ Arthropoda
$(ii)$ Amphibia
$(iii)$ Porifera

State the reason for the following:
$(i)$ Nematodes have a pseudocoelom.
$(ii)$ Arthropods have an open circulatory system.
$(iii)$ Echinoderms are named as such.

Real organs are absent in

Fungi are heterotrophic eukaryotic organisms and have a cell wall made of chitin. Name five cell organelles that are present in the fungal cell. Also,state two structural differences between a plant cell and a fungal cell. Which life form occurs due to the association of cells of fungi and algae?

Corals are: