Food Webs & Functional Feeding Groups
Since the late 1970s, insect groups in streams have been classified into Functional Feeding Groups rather than the standard trophic levels. This food web scheme was adopted because many insects in streams eat across several trophic levels making the trophic level classification system not very useful in describing these food webs.
The Functional Feeding Group classification system groups aquatic insects in terms of both how and what they eat. There are 6 major Functional Feeding Groups (see table below). Classifying aquatic insects by how and what they eat is a useful way to introduce insects to your students without having to know the names of the animals.
|
Functional Feeding Group |
What do they eat? |
Where do they fit in the standard food web? |
What examples of stream insects are in this group? |
| Shredders | Large pieces of living and dead plant material (Coarse Particulate Organic Matter [CPOM]) | Some Herbivores; some Detritivores | Some stoneflies, caddisflies, beetles, and flies |
| Collectors | Small pieces of dead decomposing plant material and feces from other organisms (detritus); Fine Particulate Organic Matter (FPOM)) | Detritivores | Some mayflies, caddisflies, flies, and beetle |
| Scrapers | Periphyton- algae and associated material attached to rocks and other substrates | Herbivores | Some mayflies, caddisflies, beetles and flies |
| Piercers of Plants | Living plants or cells of filamentous (macroscopic) algae | Herbivores | Some spongilliflies, dobsonflies and caddisflies |
| Predators | Living animals | Carnivores | Some stoneflies, dragonflies, dobsonflies, beetles, and flies |
| Parasites | Living animals | Parasite | Wasps and Flies |
|
Adapted from table 6C, Merritt et al. 2006 |
|||
