Considering the age of the various segments of an annelid

Last updated: 10/2/2023

Considering the age of the various segments of an annelid such as an earthworm each segment doubles several times in life so all of the segments are half or one fourth new at any one time new segments are added just in front of the pygidium so the oldest segments are at the anterior end segments grow and duplicate in a haphazard fashion preventing their use in identification they are born with all segments present and these merely grow in size this allows segment count to be a major feature in their identification new segments are added just behind the prostomium so the oldest segments are at the posterior end