Leeches are:

Which animal in the phylum $Annelida$ exhibits separate sexes (dioecious)?

What type of body cavity (coelom) is present in an earthworm?

$A$ student was given a specimen to identify on the basis of the characteristics given below.
$(i)$ They are metamerically segmented.
$(ii)$ Presence of closed circulatory system.
$(iii)$ They have circular and longitudinal muscles for locomotion.
Identify the specimen.

Segmentation in the body is first observed in which of the following:

Write the general characters of Phylum Annelida.