Rattlesnakes
The name 'rattlesnake' refers to any snake in the genera Crotalus and Sistrurus, in the subfamily Crotalinae (pit vipers). There are 32 known species of rattlesnake with many other subspecies, each of which can differ some in size, markings, location and behavior.
Range and Habitat
Rattlesnakes are found throughout the Americas. Their range extends from Southern Canada to Central Argentina, but are most commonly found in southwestern United States and Mexico. They can survive at elevations of more than 10,000 feet. Rattlesnakes live in a variety of habitats, including grasslands, deserts, swamps, and meadows, though most species prefer to live in rocky areas Rattlesnakes can also survive at a variety of temperature ranges, Rattlesnakes' ability to live in a variety of habitats at a variety of temperatures allows them to live in many locations, giving them a wide range across the American continents.
Behavior
Rattlesnake behavior can differ significantly based on the species of snake and its location., because rattlesnake behavior is highly dependent on the surrounding temperature. During the winter, many rattlesnakes in colder locations hibernate underground in snake dens, and they often share a den with many other rattlesnakes. Rattlesnakes usually return to the same den every year, and will sometimes migrate several miles to get there. The snakes emerge fro hibernation as the weather gets warmer. During the hottest months, they are often only active at night, when the temperature is cooler. They spend their days in shaded areas unless their internal temperature gets to low, in which case they sun themselves to warm back up. Rattlesnakes are also distinctive because of the rattle on their tails. They shake this rattle to warn or alert anything which they find threatening.
Anatomy
Generally, rattlesnakes share the same anatomy with most species of snakes. Snakes (or organisms which can be classified under the suborder Serpentes) are legless reptiles. They are also cold-blooded, meaning that they take on the temperature of their surroundings. They move by contracting their muscles to curve their body and move it along the ground. Snake skins are composed of scales, and they shed the outer layer periodically in order to remove worn skin and to remove parasites..Snakes also have forked tongues, which they use for the sense of smell. They flick out their tongues to collect airborne particles, then transports these particles to an organ in the roof of the mouth called the Jacobson's organ, which can identify the particles. Rattlesnakes have also evolved several beneficial characteristics separate from other snakes which help them to survive in the wild.
Like other snakes in the Crotaline subfamily, rattlesnakes have a pit on the side of their head, between the eye and the nostril, which is heat sensitive. These pits allow rattlesnakes to sense warm-blooded prey by detecting the thermal radiation given off by their bodies. The thermal radiation is detected in the form of infrared light, which passes through the pit and warms the pit membrane inside. When this membrane is warmed, the information is sent to the snake's brain, which it can use to create a thermal map of its surroundings. This is especially helpful to the snake when the light levels are low so it cannot see its prey.
Range and Habitat
Rattlesnakes are found throughout the Americas. Their range extends from Southern Canada to Central Argentina, but are most commonly found in southwestern United States and Mexico. They can survive at elevations of more than 10,000 feet. Rattlesnakes live in a variety of habitats, including grasslands, deserts, swamps, and meadows, though most species prefer to live in rocky areas Rattlesnakes can also survive at a variety of temperature ranges, Rattlesnakes' ability to live in a variety of habitats at a variety of temperatures allows them to live in many locations, giving them a wide range across the American continents.
Behavior
Rattlesnake behavior can differ significantly based on the species of snake and its location., because rattlesnake behavior is highly dependent on the surrounding temperature. During the winter, many rattlesnakes in colder locations hibernate underground in snake dens, and they often share a den with many other rattlesnakes. Rattlesnakes usually return to the same den every year, and will sometimes migrate several miles to get there. The snakes emerge fro hibernation as the weather gets warmer. During the hottest months, they are often only active at night, when the temperature is cooler. They spend their days in shaded areas unless their internal temperature gets to low, in which case they sun themselves to warm back up. Rattlesnakes are also distinctive because of the rattle on their tails. They shake this rattle to warn or alert anything which they find threatening.
Anatomy
Generally, rattlesnakes share the same anatomy with most species of snakes. Snakes (or organisms which can be classified under the suborder Serpentes) are legless reptiles. They are also cold-blooded, meaning that they take on the temperature of their surroundings. They move by contracting their muscles to curve their body and move it along the ground. Snake skins are composed of scales, and they shed the outer layer periodically in order to remove worn skin and to remove parasites..Snakes also have forked tongues, which they use for the sense of smell. They flick out their tongues to collect airborne particles, then transports these particles to an organ in the roof of the mouth called the Jacobson's organ, which can identify the particles. Rattlesnakes have also evolved several beneficial characteristics separate from other snakes which help them to survive in the wild.
Like other snakes in the Crotaline subfamily, rattlesnakes have a pit on the side of their head, between the eye and the nostril, which is heat sensitive. These pits allow rattlesnakes to sense warm-blooded prey by detecting the thermal radiation given off by their bodies. The thermal radiation is detected in the form of infrared light, which passes through the pit and warms the pit membrane inside. When this membrane is warmed, the information is sent to the snake's brain, which it can use to create a thermal map of its surroundings. This is especially helpful to the snake when the light levels are low so it cannot see its prey.
The most distinctive physical characteristic that all rattlesnakes share is the rattle located on the end of their tail. This rattle is composed of modified scales. which work together to form a series of interlocking segments. Every time a rattlesnake sheds its skin a new segment is added to the rattle. This happens because rattlesnakes are born with an enlarged and rounded tip on the end of their tail. When a snake sheds its skin, the skin is peeled off its body, starting at the mouth and going down to the tail, and the skin is turned inside out. When rattlesnakes shed their skin, it stays attached to the enlarged tip of the tail, forming a new segment of the rattle. When the snake shakes its tail, these segments vibrate against each other, making a rattling noise.
Venom and Venom Delivery
The most noteworthy characteristic of rattlesnakes, and the most important for this project, is their venom and venom delivery system. Rattlesnakes use their venom to kill their prey without having to fight it. They can often bite their prey and leave, then come back to find it once it has died. This saves the rattlesnakes energy, and keeps them from sustaining injuries from fighting their prey. Rattlesnakes also use their venom as a self-defense mechanism, to injure anything that they feel is a threat.
While rattlesnakes are often refereed to as poisonous snakes, this is actually not the case. Poisons are absorbed through the skin or digestive system, whereas rattlesnakes have to inject their venom directly into the bloodstream. They do this by biting their victims and piercing their skin using fangs. which then inject the venom into the prey.
Rattlesnake fangs are long and curved. Like other pit vipers, their fangs are located in the front of their mouth, and are retractable-the fangs are folded against the roof of the mouth when they are not in use. When a rattlesnake strikes, the muscles in its mouth contract, rotating the fangs into position. Each fang is connected to a venom gland on the side of the snake's head by a duct. The venom gland produces and stores the snake's venom. When the snake extends its fangs, its jaw muscles contract, squeezing the venom glands and forcing the venom to flow out. The snake's fangs are hollow, and the venom flows out through these fangs into the bitten organism.
Once the snake venom is inside an organism, it can have a variety of toxic effects. Rattlesnake venom is made up of several types of proteins which can interact with various parts of the body. This can cause a variety of pharmacological effects, some of which are described below.
Neurotoxins-Neurotoxic proteins interfere with the firing of neurons. Neurons are nerve cells. They carry information from the
brain to the body and vice versa. They transmit this information using electrical signals. Neurons are connected to each other by
synapses, and each synapse includes a small space, called the synaptic gap. Electric signals can't cross this gap, so the
information is carried by neurotransmitters. When an electric signal travels through a neuron, it triggers the intake of calcium ions.
These calcium ions flow through the neuron membrane and become concentrated in the end of he neuron. There, the calcium
ions interact with proteins, causing them to change shape and release neurotransmitters into the synaptic gap. The
neurotransmitters bind with receptors on the next neuron, activating the receptor molecule. This causes a change in voltage in the
second neuron, creating the electric signal to continue transmitting information. Neurotoxic proteins interfere with this exchange
of information at the synapse. They can either interfere with the firing of neurotransmitters from the first neuron (presynaptic
neurotoxins) or the receptor on the second neuron (postsynaptic neurons). Most neurotoxic proteins in rattlesnakes are
presynaptic. By preventing the firing of neurotransmitters, these proteins prevent signals from being sent through the body. This
can lead to paralysis and eventually death. Of the toxic proteins in snake venom, neurotoxins are often the most toxic.
Hemotoxins-Hemotoxins interfere with red blood cells. They can do this in a variety of ways. Some hemotoxins destroy red
blood cells (hemolysis), some disrupt the clotting abilities of blood, either preventing blood clotting or causing rapid unwanted
clotting (platelet aggregation inhibition/activation), and some destroy the lining of blood vessels, allowing blood to seep
into tissues and causing hemorrhaging. Hemotoxins can also cause inflammation and swelling. By interfering with the blood,
hemotoxins can cause severe damage to organs and tissues because they can't function without oxygen. The first cause of death
from hemotoxins is the loss of blood pressure, followed by organ failure. Hemotoxic proteins often cause the most pain to the
victim.
Mytotoxicins-Cytotoxic proteins affect muscles. They cause muscle necrosis, or the death of muscle cells, by destroying
muscle fiber proteins.
Cytotoxicins-Cytotoxic proteins cause death to living cells. Unlike other proteins, they do not affect only one type of cell.
Cytotoxins can destroy all types of cell in the body. Cytotoxins often kill cells by breaking apart their cell membranes. Unlike other
venom types which can use the bloodstream to spread to various parts of the body, cytotoxins are often contained in the area
nearest to the bite.
While all of these proteins can be found in snake venoms, there are many snakes that do not have all of the types of toxic protein. Some snakes do not have neurotoxic proteins, others are lacking in hemotoxins. Snakes also differ in the concentration and strength of different toxins. This variety can even happen among species, so that two snakes in the same species can have different venoms with different effects.
Snake venom is highly effective at killing its prey. Some snakes even have venoms which are adapted to certain types of prey. These snakes have specialized venom, which is more effective on their prey species than any other organism. Snakes have such effective and specialized venom because their venom experiences accelerated evolution. The genes which code for snake venom evolve faster than typical genes, This is because genes are made of two components: exons and introns. Exons code directly for proteins while introns do not. In most organisms, introns experience more changes than exons. This does not lead to any significant change in the organism because introns do not affect the building of proteins, so they do not affect the organisms characteristics. However in snake venom genes, the exons change much faster than the introns do, which can cause significant changes to the proteins in the venom. This causes snake venom to evolve faster than normal organisms, allowing it to become more selective.
The most noteworthy characteristic of rattlesnakes, and the most important for this project, is their venom and venom delivery system. Rattlesnakes use their venom to kill their prey without having to fight it. They can often bite their prey and leave, then come back to find it once it has died. This saves the rattlesnakes energy, and keeps them from sustaining injuries from fighting their prey. Rattlesnakes also use their venom as a self-defense mechanism, to injure anything that they feel is a threat.
While rattlesnakes are often refereed to as poisonous snakes, this is actually not the case. Poisons are absorbed through the skin or digestive system, whereas rattlesnakes have to inject their venom directly into the bloodstream. They do this by biting their victims and piercing their skin using fangs. which then inject the venom into the prey.
Rattlesnake fangs are long and curved. Like other pit vipers, their fangs are located in the front of their mouth, and are retractable-the fangs are folded against the roof of the mouth when they are not in use. When a rattlesnake strikes, the muscles in its mouth contract, rotating the fangs into position. Each fang is connected to a venom gland on the side of the snake's head by a duct. The venom gland produces and stores the snake's venom. When the snake extends its fangs, its jaw muscles contract, squeezing the venom glands and forcing the venom to flow out. The snake's fangs are hollow, and the venom flows out through these fangs into the bitten organism.
Once the snake venom is inside an organism, it can have a variety of toxic effects. Rattlesnake venom is made up of several types of proteins which can interact with various parts of the body. This can cause a variety of pharmacological effects, some of which are described below.
Neurotoxins-Neurotoxic proteins interfere with the firing of neurons. Neurons are nerve cells. They carry information from the
brain to the body and vice versa. They transmit this information using electrical signals. Neurons are connected to each other by
synapses, and each synapse includes a small space, called the synaptic gap. Electric signals can't cross this gap, so the
information is carried by neurotransmitters. When an electric signal travels through a neuron, it triggers the intake of calcium ions.
These calcium ions flow through the neuron membrane and become concentrated in the end of he neuron. There, the calcium
ions interact with proteins, causing them to change shape and release neurotransmitters into the synaptic gap. The
neurotransmitters bind with receptors on the next neuron, activating the receptor molecule. This causes a change in voltage in the
second neuron, creating the electric signal to continue transmitting information. Neurotoxic proteins interfere with this exchange
of information at the synapse. They can either interfere with the firing of neurotransmitters from the first neuron (presynaptic
neurotoxins) or the receptor on the second neuron (postsynaptic neurons). Most neurotoxic proteins in rattlesnakes are
presynaptic. By preventing the firing of neurotransmitters, these proteins prevent signals from being sent through the body. This
can lead to paralysis and eventually death. Of the toxic proteins in snake venom, neurotoxins are often the most toxic.
Hemotoxins-Hemotoxins interfere with red blood cells. They can do this in a variety of ways. Some hemotoxins destroy red
blood cells (hemolysis), some disrupt the clotting abilities of blood, either preventing blood clotting or causing rapid unwanted
clotting (platelet aggregation inhibition/activation), and some destroy the lining of blood vessels, allowing blood to seep
into tissues and causing hemorrhaging. Hemotoxins can also cause inflammation and swelling. By interfering with the blood,
hemotoxins can cause severe damage to organs and tissues because they can't function without oxygen. The first cause of death
from hemotoxins is the loss of blood pressure, followed by organ failure. Hemotoxic proteins often cause the most pain to the
victim.
Mytotoxicins-Cytotoxic proteins affect muscles. They cause muscle necrosis, or the death of muscle cells, by destroying
muscle fiber proteins.
Cytotoxicins-Cytotoxic proteins cause death to living cells. Unlike other proteins, they do not affect only one type of cell.
Cytotoxins can destroy all types of cell in the body. Cytotoxins often kill cells by breaking apart their cell membranes. Unlike other
venom types which can use the bloodstream to spread to various parts of the body, cytotoxins are often contained in the area
nearest to the bite.
While all of these proteins can be found in snake venoms, there are many snakes that do not have all of the types of toxic protein. Some snakes do not have neurotoxic proteins, others are lacking in hemotoxins. Snakes also differ in the concentration and strength of different toxins. This variety can even happen among species, so that two snakes in the same species can have different venoms with different effects.
Snake venom is highly effective at killing its prey. Some snakes even have venoms which are adapted to certain types of prey. These snakes have specialized venom, which is more effective on their prey species than any other organism. Snakes have such effective and specialized venom because their venom experiences accelerated evolution. The genes which code for snake venom evolve faster than typical genes, This is because genes are made of two components: exons and introns. Exons code directly for proteins while introns do not. In most organisms, introns experience more changes than exons. This does not lead to any significant change in the organism because introns do not affect the building of proteins, so they do not affect the organisms characteristics. However in snake venom genes, the exons change much faster than the introns do, which can cause significant changes to the proteins in the venom. This causes snake venom to evolve faster than normal organisms, allowing it to become more selective.