Stalked Ciliates

Identification

• Attached to floc via stalks
• Measure 30-80 µm in length
• Can form large colonies with multiple heads (zooids)
• Zooids are an inverted bell shape with cilia on top

Why Do I Have It?

• Found in healthy sludge age
• Colonies indicative of moderately old sludge
• BOD has been reduced and most free-dispersed bacteria have been flocculated

Treatment

Colonies can be indicators of moderately old sludge age. If you are concerned about your plant conditions contact a technical rep for information and recommendations.

Under the Microscope and In Your Plant

Stalked ciliates are one of the most important protozoa in a wastewater system for aiding in clear effluent. There are two different distinct types of stalked ciliates: those with a shell, or a lorica, and those without. The first and most common type of stalked ciliates are those without a shell. All types have an inverted bell-like head, or zooid. These heads have cilia on top that are used for feeding. The cilia are used to create a water current in order to filter food particles, such as free bacteria, algae, or smaller protozoan into their mouth. This type of feeding aids in creating a clear effluent. Some types of stalked ciliates can have multiple heads, which are called colonies. If stalked ciliates are observed in large colonies, it is an indication of an older sludge age; the larger the colony, the older the sludge age. Whether colonized or not, certain species of stalked ciliates can contract their stalks (seen in the video above). When in colonies, contractions can happen either individually or simultaneously throughout the colony. Shelled stalked ciliates, such as Vaginicola and Thuricola, typically contain one or two long heads with cilia extending from the top. Some of these heads are seen with a short, thin stalk, while other species have no stalk. Both types of stalked ciliates range from 30-80 µm in size and can be identified under 100x magnification. Sometimes, if shelled stalked ciliates are observed it can be an indication of mild toxicity within a system.

Interesting Facts

• Stalked ciliates are commonly observed attached to bacteria floc; they can separate from their stalks and swim freely in order to avoid unfavorable environmental conditions