Suctoria is commonly found in wastewater systems as well as marine and freshwater systems. The family is often periphytic (attached to the substrate) or attached to aquatic invertebrates. The feeding spines can be all over the body or arranged in two groups on either side of the triangular body. Suctoreans are predatory using their spines to capture other higher life forms and suck out the nutrient-rich cytoplasm of the captured organism. Suctoreans comprise approximately 7% of all ciliates described to date and are a very diverse group of higher organisms. They range in size from 40 to 200 m. The majority of Suctoreans are non-colonial. During adverse environmental conditions, Suctoria will break away from the stalk to seek out a more favorable habitat. During this stage, the morphology changes, where the body reabsorbs the spines and extends cilia in order to move freely in the water. After locating a favorable substrate, it reverts to its more common morphology. Mature Suctoria, in their stalked morphology, are indicative of a stable, healthy biomass that is lightly loaded and well-oxygenated.

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