Question

Which functional feeding groups are involved in the process of in-stream physical breakdown of coarse material into fine particulate organic matter?
(a) Collector filterers
(b) Shredders
(c) Grazers
(d) Collector gatherers

Answer 1

Hint: Functional feeding groups are a classification system based on behavioural food acquisition mechanisms rather than taxonomic divisions. The intake of a wide variety of food items might be caused by the same general behavioural mechanisms in different species.

Complete answer:
The advantage of the functional feeding groups method is that it allows a small number of groups of organisms to be investigated collectively based on how they function and process energy in the stream environment, rather than hundreds of individual taxa. Individuals are classified based on how they receive food and the particle size of the food they consume, not on what they consume.
This method of analysis avoids the non-informative necessity of classifying the majority of aquatic insect taxa as omnivores and establishes links to basic aquatic food resource categories, coarse particulate organic matter (CPOM), and fine particulate organic matter (FPOM), which require different adaptations for their exploitation.
Scrapers (grazers) devour algae and associated debris; shredders ingest leaf litter or other CPOM, including wood; collectors (gatherers) collect FPOM from the stream bottom; filterers collect FPOM from the water column using a variety of filters; and predators feed on other consumers.
Shredders are used in the physical breakdown of coarse material into fine particulate organic matter in the stream.

So, Option B is the right choice.

Note: Species that do not fit cleanly into the other groups, such as parasites, are included in a sixth category. It's crucial to remember, though, that invertebrates use a range of food acquisition strategies.