Final answer:
Decomposers like bacteria, fungi, protozoa, and saprotrophic organisms are essential in ecosystems for breaking down dead organic matter and recycling nutrients.
Step-by-step explanation:
Decomposers play a crucial role in ecosystems by breaking down dead organic matter and recycling nutrients back into the environment. Four examples of decomposers would include specific types of bacteria, fungi, single-celled protozoa, and saprotrophic organisms, which particularly include fungi capable of decomposing wood.
These decomposers obtain nutrients and energy by breaking down the remains of dead organisms and animal wastes. Through this process, they release nutrients such as carbon and nitrogen into the soil, which plants can then absorb. Fungi, such as mushrooms, are primary decomposers of plant litter and are unique in their ability to decompose tough materials like wood by secreting enzymes.