|Lowland streaked tenrec|
|Poison dart frog|
Young predators sometimes make the mistake of attacking one of these conspicuous species. If the attacker survives the experience, it learns to avoid them in the future. The system of defense therefore works best against predators who are able to learn.
The coral snake (above) is poisonous, but the harmless milk snake (below) mimics its coloration and derives a benefit.
Aposematic colors in insects are often red, yellow, orange, and black, colors that are can be seen by birds, lizards, and primates, their chief predators. The skunk uses black and white, because that pattern is most noticeable to mammalian predators.
Aposematism on Wikipedia