Paradox of the plankton

Marine diatoms are among the many planktonic organisms that paradoxically appear to flout the competitive exclusion principle.

In aquatic biology, the paradox of the plankton describes the situation in which a limited range of resources supports an unexpectedly wide range of plankton species, apparently flouting the competitive exclusion principle, which holds that when two species compete for the same resource, one will be driven to extinction.