Definition for Rotifer
From Biology Forums Dictionary
The rotifers make up a phylum of microscopic and near-microscopic pseudocoelomate animals. Most rotifers are around 0.1–0.5 mm long (although their size can range from 50 μm to over 2 millimeters), and are common in freshwater environments throughout the world with a few saltwater species; for example, those of genus Synchaeta. Some rotifers are free swimming and truly planktonic, others move by inchworming along a substrate, and some are sessile, living inside tubes or gelatinous holdfasts that are attached to a substrate.