Because different types of food are found in distinct areas of a stream, bugs with similar feeding techniques will likely be found together in the appropriate area. Scrapers are most commonly found in parts of streams where sunlight can reach the bottom to allow algal growth. Often, sunny parts of streams are faster parts, so many scrapers have evolved mechanisms that allow them to stay attached to rocks in fast currents. It is also helpful if the layer of algae is not so thick that the bugs can't get a grip on the surface. Scrapers may include snails, certain mayfly larvae, and limpets.
Shredders feed on leaves, twigs, and other pieces of organic matter that fall into a stream.
Shredders chew up the debris into smaller particles, which can then be eaten by Collectors. Shredders include stonefly larvae and scuds. The caddisfly larvae pictured above is another example of a shredder. 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.