Rotifer

The Rotifer (also known as wheel animalcules) are a phylum of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris in 1696, and later by Antonie van Leeuwenhoek in 1703. Rotifers are part of the supergroup Spiralia, an ancient and diverse group of animals.

Classification

Rotifers belong to the kingdom Animalia, the phylum Rotifera, and the class Eurotatoria. There are around 2200 species of rotifers, grouped into two classes: the Monogononta, which have one gonad and the Bdelloidea and Seisonidea, which have two gonads.

Anatomy

Rotifers are bilaterally symmetrical and have a variety of different shapes. The head of a rotifer is called the corona, which is ciliated and creates a current that brings food into the mouth. Rotifers have a simple digestive system with a mouth, stomach, and cloaca. They also have a simple nervous system with a brain and two longitudinal nerve cords.

Reproduction

Rotifers reproduce through both sexual and asexual reproduction. In sexual reproduction, males are haploid and females are diploid. In asexual reproduction, females produce offspring from unfertilized eggs, a process known as parthenogenesis.

Ecology

Rotifers are found in many freshwater environments and in moist soil, where they inhabit the thin films of water that surround the soil particles. They eat particles up to 10 micrometres in size, including bacteria, algae, and protozoans.

See also

• Microorganism
• Zooplankton

External links

• Rotifers - Microscopy UK

• 
  Mikrofoto.de Raedertier 14
• 
  Pulchritia dorsicornuta - ZooKeys 342 001 g001
• 
  Figure 28 03 05
• 
  Bdelloid
• 
  20100708 colonial rotifer Conochilius
• 
  Sinantheria socialis
• 
  Philodina rugosa 756859
• 
  Mikrofoto.de Raedertier Ptygura pilula 2
• 
  Mikrofoto.de Brachionus quadridentatus 6
• 
  Movie of Rotifer, feeding (probably of the genus Cephalodella)
• 
  Feeding rotifer
• 
  Pair of Rotifers, likely Euchlanis, from Northeast US Pond sample