Collectors eat fine organic matter such as leaf fragments, bacteria, stream bed deposits, and waste products from other organisms. Filtering collectors feed by filtering food out of passing water with hair-like fans or by spinning a fine net. Gathering collectors feed by gathering food from the bottom. Collectors may be found in all types of stream reaches but are typically most common in lower reaches because that is where fine sediments generally accumulate. Collectors include worms, blackfly larvae like the one pictured, and many mayfly and caddisfly larvae and midges.
Predators eat other invertebrates and even fish.
Predators may actually be found anywhere in the stream ecosystem, but they are less numerous compared to other feeder types. There must be enough prey critters to support predators, or they will not be present at all. Predatory organisms include the larvae of dragonflies, damselflies, dobsonflies, adult beetles and some beetle larvae, some midge larvae, and some crane flies. For questions about information on this page, please contact Kate O'Laughlin , Ecologist. By visiting this and other King County web pages, you expressly agree to be bound by terms and conditions of the site.