Micro Gallery



Flagellates belong to the class Mastigophora and range in size from 5-20 micrometers in diameter. They are commonly ovoid or pear-shaped with one to four flagella, hair-like projections used for… Read more »


Nematodes are common and widespread metazoa.   Most are 2-3 mm long and have a long thin shape and a slightly blunt anterior end, resembling earthworms. They are rather stiff… Read more »



Amoebae range in size from 100 to 300 micrometers. They are unique in that they have no distinct shape. They continually range from round to oval to irregular shapes with… Read more »


Once thought to be the only floc-forming bacteria, this “classical floc-former” exists in 2 forms within activated sludge, fingered Zoogloea and amorphous Zoogloea. Fingered Zoogloea have many branches that look… Read more »

Purple Sulfur Bacteria

The purple sulfur bacteria belong to the phylum Proteobacteria. These bacteria are often found in stagnant waters or where there are high concentrations of Hydrogen Sulfide. In order to conduct… Read more »


Suctoria are commonly found in wastewater systems as well as marine and freshwater systems. The family is often periphytic (attached to substrate) or attached to aquatic invertebrates. The feeding spines… Read more »


Rotifers are metazoa and are the simplest of the multicellular animals. They are found in many different types of water including aeration stabilization basin systems, activated sludge, and some freshwater… Read more »

Stalk Ciliates

Stalked ciliates can be seen in single organism form or can grow in colonies. Each “head” in a colony of stalked ciliates is considered one organism. Therefore, when counting higher… Read more »

Filamentous Bacteria

Filamentous bacteria are long strands of bacteria growing end to end, resembling strands of hair or spaghetti, which interlock with each other to form a mesh.   This “mesh” will… Read more »

Water Flea

Water fleas are small, aquatic crustaceans.   They live in various environments from swamps to freshwater lakes, ponds, streams and rivers.   The most common water flea is the genus… Read more »


Algae are common in waste treatment systems and come in many forms including a filamentous form. They are usually green or brown in color and the filaments are larger than… Read more »

Tardigrades and Gastrotrichs

Tardigrades, also called water bears, are metazoan that overlap in size with protozoa, but are easy to distinguish when identifying organisms. They have a tubular pharynx, an eyespot, claws, and… Read more »

Free-swimming and Crawling Ciliates

The ciliates are so named because of the cilia, small hairs that are distributed over the entire body. Ciliates are generally ovoid or pear-shaped and maintain their shape by means… Read more »

Sphaerotilus natans

Sphaerotilus natans, S. natans for short, is a type of filamentous bacteria found in many activated sludge processes and in aerated stabilization basins (ASBs). It is commonly found in systems… Read more »