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Animal Defense against
Predators
TIP #2 for Chemical EcologyPhyllis Robinson, Keith Murphy
and Melissa Greene
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Animal Defense Against Predators
Throughout millions of years of evolution, animalshave evolved numerous ways of defending themselves
against predators. Obviously, being able to fleea predator is the choice of many prey animals we
can consider.However, there are some often overlooked but
interesting methods of defense which involve deceptionand chemistry. These include using toxic chemicals,
camouflage, and mimicry.
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Animal Defense Against Predators
Presented here are several descriptions
andexamples of animal defense.
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1. Chemical Defense
There are two main ways animals can usechemicals to defend themselves.
Animals can synthesize toxin using theirown metabolic processes, or they canaccumulate toxin from the food they eat.
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1. Chemical Defense Animals which synthesize
their own toxin are ableto convert chemicalcompounds in their body
to a poison.
There are manyamphibians that produceskin toxins. The skintoxins are produced by
special poison glands,usually located on theanimal's back orthroughout the skin. The poison dart frog has
poison glands scatteredall over its body.
Photo courtesy of Dr. John Daly
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1. Chemical Defense
In anotherexample, the firesalamander makesa nerve poison,which it can
squirt from glandson its back.
Photo courtesy of Henk Wallays, Cal. Acad. of Sciences.
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1. Chemical DefenseMany animals accumulatetoxin from their foodrather than synthesizing it
from scratch.
For example, the larvae ofMonarch butterflies accumulatetoxins from the plants theyinhabit. Birds that eat theMonarchs vomit and learn toavoid them in the future.Their bright coloration allowsbirds to remember and avoidthem.
Photo courtesy of T. W. Davies, Cal. Acad. of Sciences.
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1. Chemical Defense Interestingly, many organisms
which are distasteful advertisethis fact to predators by havingbright body colors or markings,as if to say, Notice me! Imdangerous!
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1. Chemical DefenseYou can see this in thebright colors of the
Monarch and thepoison dart frog.
Photo courtesy of Dr. John Daly
Photo courtesy of T. W. Davies, Cal. Acad. of Sciences.
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1. Chemical Defense
This is called aposematic
coloration, and is widelyused among the insectsand amphibians.
The Cream-spot Tiger is
aposematically colored.
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2. Camouflage
Animals that camouflagethemselves pretend to be
something they are not.Either their coloration,marking patterns, orentire body resemblessomething else in theirenvironment, here aleaf, an owl.
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2. Camouflage
Here an aptly namedwalking stickpretends to be atwig, in an attemptto avoid being seenby a bird or other
predator. This isan example ofcryptic coloration.
Photo courtesy of Dr. Lloyd Glenn Ingles, Cal. Acad. of Sciences.
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2. CamouflageIn this picture, a four-eyed butterfly fish usesdeceptive markings.
The large spot near thetail resembles an eye.When predators attackthe wrong end, thebutterfly fish can swim
away in the otherdirection!
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2. CamouflageSome predators also depend on camouflage, but
this time it is in order to avoid being seen by their
prey.
Here, a frogfish resemblesa sponge. Small fish
swimming nearby will beengulfed in the frogfishsenormous mouth!
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3. Mimicry
There are several types of mimicry.
The two most common types areBatesian mimicry andMullerian mimicry.
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3. MimicryBatesian mimicryoccurs when an edible mimic resembles anunpalatable or poisonous model. In this type of mimicry,
only the mimic benefits.
An example of Batesianmimicry is the scarlet kingsnake, a non-poisonous
mimic of the extremelyvenemous coral snake.
Above: scarlet king snake
Right: coral snake
John H. Tashjian
Photo courtesy of John H. Tashjian,
Cal. Acad. of Sciences.
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3. Mimicry
Another example of
Batesian mimicry isthe locust borer.This insect not onlylooks like a bee orwasp, it sounds likeone, too!
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3. Mimicry
By contrast, Mullerian mimicry occurs
when two (or more) distasteful orpoisonous organisms resemble each other.Both species benefit because a predatorwho learns to avoid one species will most
likely avoid the other, too.
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3. Mimicry
The two invertebrates on the left are different speciesof sea slugs, while the one on the right is a marineflatworm. All three secrete noxious substances andare unpalatable. Notice their similar aposematic
coloring.
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Review and SummaryThree types of defenses that animals can use
against predators include:
chemical defenseincluding synthesizing toxins andaccumulating toxins from food;
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Review and SummaryThree types of defenses that animals can use
against predators include:
chemical defense camouflage
including cryptic coloration anddeceptive markings;
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Review and SummaryThree types of defenses that animals can use
against predators include:
chemical defense camouflage
mimicryincluding Batesian and Mullerian
mimicry
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Review and SummaryThree types of defenses that animals can use
against predators include:
chemical defense camouflage mimicry
Animals constantly evolve new and improved
characteristics to capture prey or evade predators;the ongoing arms race has produced some of thewonderful organisms you have just seen!