Final answer:
Bacteria and earthworms break down matter from dead plants and animals in the food web.
Step-by-step explanation:
A detrital food web consists of organisms that feed on decaying organic matter, including decomposers that break down dead and decaying organisms. These organisms are usually bacteria, fungi, and invertebrate animals such as earthworms. They recycle organic material back into the ecosystem as they themselves are consumed by other organisms. Therefore, the two organisms in the given food web that break down matter from dead plants and animals are bacteria and earthworm.