Catenulida is an order of flatworms in the classical classification, or a class of flatworms in a phylogenetic approach. They are relatively small free-living flatworms, inhabiting freshwater and marine environments. There are about 100 species described worldwide, but the simple anatomy makes species distinction problematic.

Description

The anatomy of catenulids is simple and lacks hard parts. The mouth is located anteriorly and connects to a simple pharynx

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