What is "pleuston"

n. 1 (context ecology English) The organisms that live floating at the surface of water. 2 (context botany English) Plants that live floating at the surface of water.

Pleuston are the organisms that live in the thin surface layer existing at the air-water interface of a body of water as their habitat. Examples include some cyanobacteria, some gastropods, the ferns Azolla and Salvinia and the seed plants Lemna, Wolffia, Pistia, Eichhornia crassipes and Hydrocharis. Some fungi and fungi-like protists may be also found.