ELI5: Explain Like I'm 5

Functional extinction

Functional extinction means that a species is so rare that it is no longer able to carry out its usual roles and functions in its environment. An example of this may be a bee species that is so rare that there is not enough of them to pollinate enough flowers. As a result, the flowers may stop growing and other animals who rely on the flowers for food cannot get it anymore. When this happens, the species is said to have functionally gone extinct.