An Official Website of the Commonwealth of Kentucky
Filamentous algae are long threads, or filaments, that are formed by individual algae cells linked together. These filaments intertwine, forming a mat that resembles wet wool. Filamentous algae starts growing along the bottom in shallow water or attached to structures in the water (like rocks or other aquatic plants). Often, filamentous algae floats to the surface, forming large mats, which are commonly referred to as “pond scum” or “moss.” Filamentous algae is one of the common aquatic weed problems in Kentucky.
There are 4 different types of filamentous algae found in Kentucky (Water Net, Lyngbya, Cotton, and Silk). They all have filaments that join together to form dense mats. Below are pictures of the different types of filamentous algae and links to their individual pages.
Water net algae has filaments joined to form net-like shaped colonies; when the water is squeezed out, it resembles a fish net or hair net.
Lyngbya is a blue-green algae that is very thick and tough when pulled apart and often has a musty or foul odor.
Cotton algae is a coarse algae with branching filaments that resembles a cotton ball when the water is squeezed.
Silk algae has filaments that are very slippery and much finer than cotton algae.
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