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I'm certainly no expert so I'm not going to edit the article myself (perhaps I'm misreading it?), but the opening paragraph reads "They are mostly small, freshwater animals that feed on plankton and detritus, with the exception of the Cladocera, many of which are marine." Later in the same article is written "[Cladocera] are ubiquitous in inland aquatic habitats, but rare in the oceans." Many of them are marine and yet rare in the oceans? The actual article for Cladocera states that only 8 species are actually neritic, which doesn't seem like many at all compared to the hundred of other species in the order.