Which of the following features is not a characteristic of $Protochordata$?

Which one is the most striking or common character of the vertebrates?

You are given leech,Nereis,Scolopendra,prawn,and scorpion; all have a segmented body organization. Will you classify them in one group? If no,give the important characters based on which you will separate these organisms into different groups.

How do annelid animals differ from arthropods?

The skeleton is made entirely of cartilage in

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