3. What is the main
evolutionary novelty
presented by annelids?

Gap-fill exercise

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The main evolutionary
presented by the of the phylum
is the coelom, internal
body cavity covered by
mesoderm, feature also present
arthropods, molluscs, echinoderms
chordates. Platyhelminthes are
and nematodes are
(their internal cavity
partially covered by ).

Another important evolutionary novelty
of the annelids is the closed circulatory
system.