By now it should be coming apparent that our classification of organisms is often tentative and arbitrary, a best guess based on current information. Many other common botanical terms are used to describe analogous structures in fungi. These superficial similarities may be the result of convergent evolution between fungi and algae. There are over 100,000 known species of fungi, but the differences between species are not always readily apparent. Subtle differences in biochemistry set many fungal species apart.
Fungi are heterotrophic , and many fungi are parasitic .
Fungi and other organisms that feed on dead or decaying matter are called detritivores . Many species of fungi are predators , catching their prey with tiny lassos or miniature missiles or toxic chemicals. Fungi and bacteria are vital to the continuation of life on Earth. They are the planetary decomposers, breaking down organic matter into a form usable by other organisms. Only fungi are capable of breaking down lignin , the compound that adds stiffness to the cell walls of plants.