Culture of fish food organisms (1+1)

2.2.Introduction to rotifers

Unit 2 - Rotifers

2.2.Introduction
The rotifers (commonly called wheel animalcules) make up a phylum of microscopic and near-microscopic pseudocoelomate animals. Rotifers are microorgansims (100 to 2500 microns) that are readily found in aquatic and semi-aquatic habitats. Some are marine inhabitants, however most species are freshwater organisms. Currently there are over 1000 described species. They account for more than 90% of the zooplankton production in some freshwater systems and as such are a vital link in the food chain for most aquatic life. Rotifers are known to have a very high reproductive rate, reaching population densities of 1000 or more individuals per litre of water. Most rotifers are around 0.1–0.5 mm long (although their size can range from 50μm to over 2 millimeters), and are common in freshwater environments. Some rotifers are free swimming and truly planktonic, others move by inchworming along the substrate, and some are sessile, living inside tubes or gelatinous holdfasts that are attached to a substrate. Rotifers are an important part of the freshwater zooplankton, being a major food source and with many species also contributing to the decomposition of soil organic matter.

Rotifer