Understanding Evolution

Aposematic animals

Many animals are camouflaged or hide from predators to avoid being eaten, but incredibly, some have evolved to grab a predator's attention with conspicuous signals — it's a bit like yelling at the school bully, "Hey, bozo! Over here!" When would such a strategy make sense? Well, it only works when the prey animals teem with defensive toxins or bristle with other hidden weaponry. Animals that warn predators of their dangerous nature are called aposematic. Lionfish advertise their venomous spines with waving flags and banners. Bright or contrasting color patterns, such as the yellow and black stripes of a wasp, serve as common aposematic signals. While aposematic coloration usually signals danger, any kind of warning signal could be considered aposematism — for example, the rattle of a rattlesnake.

Take a look around next time you go for a walk. Do you notice any conspicuous animals? Watch out — they may be trying to tell you something...


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Lionfish photo by Gerald and Buff Corsi © California Academy of Sciences; European paper wasp photo provided by Joyce Gross; Western diamondback rattlesnake photo by Gary M. Stolz

Understanding Evolution © 2021 by The University of California Museum of Paleontology, Berkeley, and the Regents of the University of California