Functional Extinction
A species that still exists biologically but has lost its ecological role and can no longer function meaningfully in its ecosystem.
A state in which a species persists in small numbers or isolated populations but no longer plays a significant ecological role or interacts meaningfully with its environment. The organism survives but is functionally absent from ecosystem processes—unable to reproduce successfully, interact with other species, or maintain population viability without human intervention.
What this means in real life
A coral reef may still have living coral colonies after bleaching, but if they're too sparse and fragmented to support fish, filter nutrients, or reproduce, the reef has become functionally extinct—it looks like a reef but no longer works as one.
What it isn’t
Not the same as true extinction, where the species disappears entirely. A functionally extinct organism still exists biologically; it simply cannot sustain itself or contribute to its ecosystem without human help.
Commonly misused online
Often conflated with 'critically endangered' or used to mean 'almost extinct.' Social media treats it as simply 'very rare,' missing the key point that the species has lost its ecological purpose, not just its numbers.