Cold Blooded Killers and Scaly Survivors

All living things need energy for their bodies to function.  That is why you’ve got to eat!  Predator species must evolve adaptations that enable them to catch and kill their prey because if they can’t find food they can’t survive.  Prey species must evolve adaptations that protect them from predators because if they get eaten they don’t 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 can’t see it.  Animals that don’t blend in don’t survive and if they don’t survive, they won’t 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 snake’s body blends in with the darker green top surface of the leaves.  The pale color on the bottom of the snake’s 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 “bad gene” that can occur during cell division when sex cells are formed. 

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.

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 couldn’t 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 predator’s 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 don’t 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.

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 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 iguana’s 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. 

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.     

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.