What are decomposers in general mean?

Decomposers are an essential part of the food chain. Decomposers, or saprotrophs, break down dead plants and animals into chemical nutrients like carbon and nitrogen that are released back into the soil, air, and water, so they can be reused. The three main types of decomposers are bacteria, fungi, and scavengers.
Bacteria are the smallest of all living organisms. They eat dead animal carcasses and plants. Actinomycetes are a form of fungi-like bacteria. They decompose tough plant tissues like bark, paper, and stems.

Fungi release enzymes that decompose dead plants and animals. They absorb nutrients from the organism they are decomposing. Fungi are very efficient in breaking down tough organisms like wood and often work together with bacteria to decompose plants.

Scavengers are animals that eat dead plants and animals. Cockroaches, the Dung Beetle, and flies are examples of scavengers. Worms, like the earthworm, eat dead plants, animals, and small pebbles. Their waste comes out in "casts." Theses casts are rich in nutrients like nitrogen, phosphorus, and potash.

Decomposers help complete the Food Web cycle, returning essential molecules to the producers.