14. Describe the differences among the three macroinvertebrate categories and provide an example of each.

Macroinvertebrates are organisms that are large (macro) enough to be seen with the naked eye and lack a backbone (invertebrate). They are commonly found in streams, rivers, and wetlands, where they play a crucial role in the ecosystem. They are divided into three categories based on their tolerance to pollution: pollution-sensitive, pollution-tolerant, and those with moderate tolerance.

1. Pollution-sensitive species: These macroinvertebrates require clean water with high levels of dissolved oxygen. Their presence indicates good water quality. An example of a pollution-sensitive macroinvertebrate is the mayfly (Ephemeroptera). Mayfly larvae are often found in areas with fast-moving water, where they cling to rocks and feed on algae and detritus.

2. Pollution-tolerant species: These are species that can survive in lower quality water with lower dissolved oxygen levels. They are often found in areas where pollution-sensitive species cannot survive. An example of a pollution-tolerant macroinvertebrate is the midge larvae (Chironomidae). Midges are able to live in a variety of aquatic environments, including those that are polluted.

3. Moderately pollution-tolerant species: These species can tolerate some pollution but do not thrive in water as contaminated as the places that pollution-tolerant species can endure. An example of a moderately pollution-tolerant macroinvertebrate is the crayfish. Crayfish can be found in areas with moderate water quality and feed on a variety of plant and animal matter.