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

(N/A) $(i)$ Arthropoda: They possess jointed appendages and a chitinous exoskeleton.
$(ii)$ Amphibia: They are adapted to live both in water and on land,and they typically have moist,glandular skin without scales.
$(iii)$ Porifera: They are multicellular organisms with a body characterized by numerous pores (ostia) and a canal system for water circulation.