Final answer:
Fungal bodies are primarily made up of hyphae, which form a larger structure called a mycelium. These fungi, with their cell walls made mostly of chitin, have both vegetative and reproductive stages, where fruiting bodies can produce spores for reproduction.
Step-by-step explanation:
Fungus bodies are composed of thin, threadlike filaments known as hyphae. These hyphae are the building blocks of the fungal structure. Most fungi, except for yeasts which grow as single cells, develop these filamentous structures. The collection of these hyphae is referred to as a mycelium. The cell wall of fungi is made largely of chitin and functions similarly to the cell walls in plants. Fungi can be multicellular organisms that have both vegetative and reproductive stages. During the vegetative stage, the fungus exists in a network of hyphae, and in the reproductive stage, it may form more visible structures like mushrooms. These reproductive structures, known as fruiting bodies or sporocarps, are involved in the production of spores for fungal reproduction.
The mycelium of a fungus can span a considerable area and remain mostly hidden from view, as is the case with some large fungal organisms like the "humongous fungus" Armillaria ostoyae. Fungi play a crucial role in ecosystems as decomposers by producing enzymes that help break down various organic materials, allowing them to absorb nutrients.