"The Clitellata are a class of annelid worms, characterized by having a clitellum - the ´collar´ that forms a reproductive cocoon during part of their life cycles. The clitellates comprise around 8,000 species. Unlike the class of Polychaeta, they do not have parapodia and their heads are less developed." - (en.wikipedia.org 26.04.2021)
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