The biology and ecology of lotic rotifers and gastrotrichs

1 The occurrence of Rotifera and Gastrotricha in the meiobenthos of lotic habitats is reviewed. About 150 rotifer and 30 gastrotrich species are reported in such habitats worldwide. 2 The two phyla share some morphological and biological features that might account for their presence in the meiofauna. Small-size, a soft and elongate body, adhesive glands on the posterior body end, movement through cilia, relatively short life cycles, parthenogenesis and dormant stages are common characteristics. 3 Most species of both taxa inhabiting the superficial sediments in streams and rivers may move downward into the hyporheos in response to both biotic (predation) and abiotic (spates, erosion, desiccation) disturbances.