Animal Defense vs Predators

7/28/2019 Animal Defense vs Predators

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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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chemical defense camouflage

including cryptic coloration anddeceptive markings;


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chemical defense camouflage

mimicryincluding Batesian and Mullerian

mimicry


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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!

Animal Defense vs Predators

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