Answer:
<u>a food web</u>
Explanation:
What they saw was a food web, which refers to connections of food chains showing how energy and nutrients are transferred from one organism to the other.
In this example, we observe there are <u>seven</u> organisms (fish, algae, snails, insects, frogs, raccoons + bacteria contained in the pond) in focus here.
The green algae are Producers (because it produces its own food, not dependant on others)
The bacteria act as Decomposers. ( because they process organic waste into meaningful natural nutrients again)
The other organisms are Consumers. (because they are dependant on others for their nutrition).