Aquatic insects and other macroinvertebrates in Lake Superior Streams

Freshwater macroinvertebrates include the aquatic insects, mites, worms, snails, and crayfish. The term macroinvertebrate just means that they are animals without backbones that are larger than ½ millimeter (the size of a pencil dot). They are also often called benthic macroinvertebrates or more simply "benthos" because they live on surfaces like rocks, logs, sediment, debris and aquatic plants during some period in their life.

Benthos are an important part of the food chain, especially for fish. Many feed on algae and bacteria which are on the lower end of the food chain. Some shred and eat leaves and other organic matter that enters the water. Because of their abundance and position as "middleman" in the aquatic food chain, benthos play a critical role in the natural flow of energy and nutrients. As benthos die, they decay, leaving behind nutrients that are reused by aquatic plants and other animals in the food chain.

See our Aquatic Invertebrate Identification pages to learn the habits and habitat of the different orders of benthos.