Respiration. In some annelids, including earthworms, all respiration is via the skin. However, many polychaetes and some clitellates (the group to which earthworms belong) have gills associated with most segments, often as extensions of the parapodia in polychaetes.

How do annelids breathe?

They breathe through their skin. Air dissolves on the mucus of their skin, so they MUST stay moist to breathe. If worms dry out, they suffocate. As fresh air is taken in through the skin, oxygen is drawn into the worm's circulatory system, and the worm's hearts pump the oxygenated blood to the head area.

What do annelids and molluscs have in common?

Like mollusks, however, they have a coelom. ... Annelids have other similarities with mollusks, including: A closed circulatory system (like cephalopods). An excretory system consisting of tubular nephridia.