Segmentation in the body is first observed in which of the following? (a) Platyhelminthes (b) Aschelminthes (c) Annelida (d) Arthropoda


-Priyanti, Subject Matter Expert at Edumarz

Solution: ( c ) Annelida

Proper segmentation of bodies was first observed in annelids, followed by that in arthropods. Annelids exhibit metameric segmentation, i.e., body is divided into segments by ring-like constrictions called grooves or annuli externally and by transverse septa internally. All segments in the metamers contain nearly identical representatives of the organ system, are of the same age and are discrete individually controllable units. This enables the annelids like earthworms to elongate one part and shorten another part of their body simultaneously.

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