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Cold Blooded Killers and Scaly Survivors

All living things need energy for their bodies to function.  That is why youíve got to eat!  Predator species must evolve adaptations that enable them to catch and kill their prey because if they canít find food they canít survive.  Prey species must evolve adaptations that protect them from predators because if they get eaten they donít survive.  These predator and prey adaptations are some of the most important and amazing animal adaptations.

The most common color adaptation is camouflage.  Most predators find prey by seeing them and if the prey blends in with its environment they canít see it.  Animals that donít blend in donít survive and if they donít survive, they wonít have offspring.  Animals that blend in survive and have offspring that look like them and blend in.  Each new generation of animals will have better camouflage than the the one before it because predators elimate the animals that don't blend in. If you understand this simple process, you understand how life works.  This process is natural selection, which is a part of evolution.  In this case, the predators cause natural selection and the color of the prey is the adaptation.

The Rough Green Snake is a tree snake that is common in Kentucky.  Its color blends in perfectly with its environment.  The darker color on the top of the snakeís body blends in with the darker green top surface of the leaves.  The pale color on the bottom of the snakeís body blends in the lighter green bottom surface of the leaves.  This bicolor camouflage protects this snake from predators from above and from below.

The Milk Snake is an example of warning coloration.  When an animal has bold bright colors, it means that it might be dangerous.  Warning coloration can be seen in Poison Dart Frogs, Bees, and even in Skunks.  It is unusual but not extremely rare.  The Milk Snake is not poisonous.  It copies the color and pattern of the venomous Coral Snake.  This rare example of a harmless animal copying the warning coloration of a dangerous animal is called mimicry.  The predator sees the warning coloration, which is a universal sign of danger, and it thinks that the Milk Snake is dangerous.  The warning coloration protects the Milk Snake even though it is not a venomous snake.

The normal color for a Corn Snake is red and black like the red and black kernels in an ear of Native American corn or maize.  This color blends in well with the leaves on the forest floor.  The gray snake is also a Corn Snake.  It has a mutation that prevents it from making the red color.  A mutation is a genetic mistake or ďbad geneĒ that can occur during cell division when sex cells are formed. 

In a forest environment the normal Corn Snake has better camouflage and the gray Corn Snake is the one that is seen and captured by predators.  This eliminates the gray Corn Snake through natural selection.  In some environments such as dry grasslands in Florida, the gray color is better camouflage than the normal color.  Predators will find and kill the normal Corn Snakes, leaving the gray Corn Snakes to survive and produce offspring that are gray.  After several generations, the whole population of Corn Snakes in that environment is gray  instead of the normal color.  When a mutation becomes an advantage like this we call it an adaptation.

The other color mutation in Corn Snakes involves a gene that prevents the snake from producing any black color.  These snakes are bright orange and would not have good camouflage for any environment so they are not found in the wild.   Corn Snakes with both color mutations don't have red or black and are called Snow Corns.  When breeders produce these snakes with color mutations they can sell them for more than they can get for a normal Corn Snake.  Breeding animals for certain traits is called artificial selection.

The food chain is a simple model we use to explain how different living things are linked together to get the energy they need to survive.   Producers get their energy from the sun.  They are able to capture sunlight and convert it into energy they can use and store through photosynthesis.  Living things that canít make their own energy from sunlight are called consumers.   Consumers that eat producers are primary consumers or herbivores, consumers that eat primary consumers are secondary consumers or carnivores, and consumers that eat secondary consumers are tertiary consumers or top carnivores.  Another important group of consumers are the decomposers that eat dead things and recycle the nutrients.

In aquatic ecosystems, most of the producers are tiny organisms that can only be seen under the microscope.  In a drop of pond water you will find a world of microscopic creatures. These tiny creatures at the bottom of the food chain are called plankton.  Most of these are single celled organisms called Protists.  Some move with many short paddle-like structures called cilia while others have one or two long flagella that swish back and forth like a tail.  The Protists that are green are producers.  The green pigment is chlorophyll, the same pigment plants use to absorb energy from sunlight and produce their own food.  Other protists are consumers.  Other consumers in plankton are tiny animals with bodies that are made up of many cells. In an aquatic food chain, the larger creatures eat the smaller creatures and  the smallest are at the bottom of the food chain while the largest are at the top. 

   

The Alligator Snapping Turtle is the largest freshwater turtle in North America.  At over 200 pounds, it is safe to say that these turtles are at the top of the food chain!  Alligator Snappers are found in Kentucky but only in very large lakes and rivers.  The snapping turtle you are familiar with is a different species called the Common Snapping Turtle.  Both of these snapping turtles are adapted for living on the bottom.  They have powerful legs and long sharp claws for digging along with a long tail they can wrap around things to hold on. Common Snappers get plenty big with a large adult weighing   40-50 pounds but they are nowhere near as large and an Alligator Snapper.  Although these two turtles look very much alike, the Alligator Snapper has bumps on its shell like Alligator skin while the Common Snapper has a smooth shell.

Alligator Snappers also have an adaptation with their tongue that Common Snappers do not.  Part of their tongue looks like a worm and they use it to lure fish in close to their mouth.  The Alligator Snapper sits stone still on the bottom with its mouth wide open while it wiggles its tongue making it look just like a worm.  When a fish comes close enough the snapper strikes with its lightening fast neck and powerful jaws.  The fish think they have found something to eat but they become the meal instead!  This is one of the most amazing predator adaptations in nature.

         

 

The Alligator Snapping turtle is an omnivore because it eats both plants and animals.  We could say it is at the top of the food chain because it has no predators, but we could also say it near the bottom of the food chain because it eats plants.  The food chain explains how where energy comes from and how energy flows through an ecosystem but it does not explain what an animal eats.  We use the food web to show that.  A food web links different animals in the ecosystem together based on what eats what.  This illustrates the complex interdependence different animals within an ecosystem have with one another.

One of the biggest differences between an aquatic food chain and a land food chain is the size of the producers.  While most producers in an aquatic ecosystem are microscopic, the most important producers in a forest are trees and these are some of the largest living things on earth!  Insects are extremely important in the food chain in a land ecosystem because the primary consumers or herbivores that feed on plants are mostly insects.  Insects are the most important animals on earth.  Not only are there more species of insects than all other animals combined, the insects on earth weigh many times more than all of the other animals on earth combined!  Without insects, the food chain would collapse and everything would starve!

The Rough Green snake eats caterpillars, which are insect larvae.  The toad is an insect eater also.  Like the Alligator Snapping turtle, it has another amazing tongue adaptation.  Toads have a tongue that is very long, very fast, and sticky on the end.  All the toad has to do is get close enough to the insect.  Its tongue does the rest. 

 

 

The Hognose Snake is a predator of toads.  Toads have evolved to have adaptations that are defenses that protect them from predators.  The Hognose snake has had to evolve to have adaptations to overcome the defenses of the toads.  Otherwise it couldnít capture and eat toads and it would become extinct.  We have seen how predators cause natural selection and adaptation in prey with camouflage.  Toads and Hognose Snakes show us that defenses of prey cause natural selection and adaptation in the predator.

Toads and other amphibians produce chemicals in their skin that are poisonous to predators.  The chemical toads produce slows the heart rate down and can stop a predatorís heart.  Adrenaline is a chemical animals produce to speed up the heart rate.  The adrenal glands that produce adrenaline in Hognose Snakes are 10 times the size of the adrenal glands of other snakes.  This adaptation has evolved because of the chemical defense of the toads.

Toads have a claw on each of their back feet so that they can dig down into soft soil and bury themselves to protect them from predators.  This is a really good defense against snakes since snakes donít have feet to dig them up!  The Hognose has a special scale on its nose that looks like a little shovel.  It uses this to dig up the toads.  This adaptation has evolved because of the defense of toads burying themselves.  The Hognose gets its common name from the fact that it uses its nose to dig like a hog.

Toads will puff their bodies up with air to make themselves look bigger and to make it hard for a predator to swallow them.  The scientific name for a Hognose Snake is Heterodont, which means ďdifferent toothĒ.  This is because Hognose snakes have long teeth on either side in the roof of their mouth that can puncture the toad and let the air out of it so that they can swallow them.  This adaptation has evolved because of the defense of the toad blowing itself up with air.  Hognose Snakes also have chemicals in their saliva that paralyze the toad and make it easier to swallow.

The Black King Snake is a local snake that eats other snakes.  As a predator of snakes, it has even evolved the adaptation of having immunity to the venom of Copperheads, Rattlesnakes and Cottonmouth Snakes.  

The Hognose Snake has a couple of defensive adaptations that it can use to protect itself from the King Snake.  Sometimes a Hognose will try to bluff its predator by spreading its head, neck and body to look bigger by and acting aggressive by hissing and striking.  If the predator is too big to bluff, the Hognose Snake plays dead.  It rolls over on its back, opens its mouth and hangs its tongue out.  Many snakes produce a fowl odor from a scent gland near their tail as a defense against predators.  The odor the Hognose Snake produces goes along with its act of playing dead.  It smells like a rotten dead animal!  Not only does the Hognose look dead, it smells dead!

The Eastern Box Turtle is the only turtle in our area that lives on land.  All turtles have a shell that is part of their skeleton and is an adaptation for protection from predators.  Box turtles have the best body armor of any turtle because they can close their shell.  If you look closely on the bottom of the shell you see a line across the middle.  This is the hinge where the front and back of the shell pivot and close.  The bottom part of the shell forms a front door the turtle can close to protect its head and front feet and a back door the turtle can close to protects its tail and back feet.  There are very few predators able to harm the box turtle when it closes off in its shell.  In fact, it would take an animal as big as a wolf or bear to crack through the shell of a full grown box turtle in order to eat it!

Some lizards have body parts that make their heads look bigger in order to fool their predators.  The Green Iguana has a flap of skin under its chin called a dewlap that it can raise and lower to make its head look bigger.  From the side with the dewlap down the iguanaís head looks twice as big as it really is!   Large lizards like the iguana use their tail as a weapon to defend themselves.  They whip their tails around and hit their attacker with it and this can be a very effective defense. 

The tail of many lizards will pop off if a predator grabs them by the tail.  If a predator is chasing a lizard they are likely to grab it by the tail since that is the part of the body they get to first, coming from behind.  The tail will pop off and the lizard will escape leaving the predator with a snack of the wiggling tail instead of a full meal of the entire lizard!   Five-Lined Skinks are the most common lizards found around here.  Young skinks have a bright blue tail.  This is an adaptation that goes along with the tail popping off.  The bright color catches the eye of predator and makes it more likely for the predator to grab the tail. 

 

Snakes jaws are very different from other reptiles.  They are adapted for swallowing prey that is larger than their heads.  This allows snakes to follow their prey into the smallest of spaces, capture them, and still be able to swallow them.  The jawbones separate at the chin and unhinge from the skull to accomplish this.  Because of this, snakes do not have a powerful crushing bite like other reptiles.  Their short teeth are sharp and curved back to help them hold on to the prey but they are unable to kill the prey with their bite.  If you are swallowing something bigger than your head you definitely want it to be dead before you swallow it!  Because of this snakes have evolved unique adaptations for killing their prey.     

The most common means of killing prey in snakes is constriction.  The snake grabs the prey in its mouth then wraps around it and squeezes it to death.  This is a very effective way to kill the small mammals that most snakes prey on because it suffocates them very quickly.  

About 10% of the snakes in the world have evolved to have venom and fangs to kill their prey.  This is why so many people are afraid of snakes.  There are lots of venomous snakes in the tropics and as many as 50,000 people die each year from venomous snake bites in poor countries in tropical areas, mainly because of the lack of medical care.

The venomous snakes in our area are called pit vipers.  Of all of the venomous snakes in the world, they have some of the most effective adaptations for killing prey.  They have long hollow fangs in the front of their mouth that are hinged to extend out when they strike and fold back when they are not in use.  The fangs are connected to a venom gland that produces a venom that actually starts to digest the prey from the inside out before the snake even swallows it!  The venom is injected into the prey like medicine is injected from a hypodermic needle.  This venom will quickly kill the small prey but it would be extremely rare for it to kill a person.  However, it causes a painful wound that will seriously damage blood vessels, muscles and other tissue around the bite if it is not treated fairly soon after being bitten.

Another adaptation that pit vipers have is a pair of heat sensitive pits between each eye and nostril.  These work like night vision goggles, allowing the snake to track and strike the warm-blooded mice and rats it preys on at night when these animals are most active.

There are a few venomous snakes in our area but people are rarely bitten, and deaths from venomous bites in the United States are extremely rare.  It is a good idea to know how to identify a venomous snake so that you can avoid them.  By knowing which snakes are venomous, you also know which ones are harmless.  Since snakes are good to have around as predators of mice and rats, the harmless snakes should be left alone to do their job.  There are three ways to easily tell a pit viper from a non-venomous snake.  The most obvious is the thick body of a pit viper.  The second is the pit viperís head, which is triangle shaped and very wide at the back.  The third is the pit viperís pupil, which is slit like a catís pupil while non-venomous snakes have a round pupil.  Another characteristic is that all pit vipers have an extremely dull texture.  If a snake is the least bit shiny, it is not a pit viper.

It is also easy to know each species of pit viper since there are only three commonly found in our area.  The most common by far is the Northern Copperhead, a reddish brown snake with a diamond shaped pattern.  Timber Rattlesnakes are the largest venomous snakes we have, but they are rarely encountered.  Some have a contrasting grey and black pattern while others have a yellow tint instead of grey.  Western Cottonmouth snakes are black snakes.   Since they are aquatic snakes, they are only found in and around water.  

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