Which among the following have an open circulatory system?
$(i)$ Arthropoda
$(ii)$ Mollusca
$(iii)$ Annelida
$(iv)$ Coelenterata

List two similarities and two differences between the features of nematodes and annelids.

Organisms having 'pores' all over the body and a canal system for bringing in food and oxygen belong to the phylum:

Write one difference for each of the following pairs:
$(i)$ Thallophyta and Bryophyta
$(ii)$ Nematoda and Annelida
$(iii)$ Amphibia and Reptilia

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.

The 'Origin of Species' was written by: