Tetrahymena

Tetrahymena is a genus of free-living ciliates, examples of unicellular eukaryotes. The genus Tetrahymena is the most widely studied member of its phylum. It can produce, store and react with different types of hormones. Tetrahymena cells can recognize both related and hostile cells.

Tetrahymena are commonly endosymbiont hosts to green algae, from which it receives oxygen, helping the host organism survive in anoxic environments. They are common in freshwater lakes, ponds, and streams.

Tetrahymena species used as model organisms in biomedical research are T. thermophila and T. pyriformis. Their main claim to fame is their role in the discovery of telomeres and telomerase which is based on the fact that ciliates are one of the richest sources for these molecules.