[MUSIC PLAYING] MORGAN SHELTON: Snakes have a far worse reputation than they deserve. What are snakes, and why are they the subject of so much fear and fascination? My name is Morgan, and these are just a few of my favorite snakes.
I'm a student at Cornell University studying animal science, and I've skipped the fear and become fascinated with reptiles and amphibians, which is the study of herpetology. I'm especially fascinated with snakes, and I want to give you a glimpse into an amazing world of snake biology.
Snakes are their own diverse order of animals in the class of reptilia. This also includes crocodilians, lizards, tuataras, and turtles. Snakes evolved about 130 million years ago in the time of the dinosaurs. Their ancestors are clearly lizards that lost their legs, but they gained a lot of advantages by being limbless.
Today, there are over 3,000 described species of snakes in the world, and there are more are being discovered all the time. Despite the immense diversity and habits of the snakes worldwide, they all share fundamental characteristics.
Snakes are divided into five major groups that differ in their biology and especially in how they feed. There are pythons and boas, which constrict their prey. Then there are elapids and vipers, which are extremely venomous. And then finally, there are the colubrids, which tend to be the generalist of the snake species.
Snakes are highly diverse and come in all shapes and sizes. The smallest snake in the world is the threadsnake, which only grows to about four inches long. That's as small as a toothpick. The longest snake in the world, on the other hand, is the reticulated python, which can grow up to a remarkable length of 30 feet. If you're five feet tall, that's six of you laid end to end to be as long as a reticulated python.
And while the reticulated python is the longest snake in the world, the biggest snake in the world is the green anaconda. The largest one on record had a width of about 12 inches. Now, how does that compare to your waist or your thigh?
Snakes live in a huge variety of habitats all around the world. They are found in tropical rainforests, desert dunes, on the prairie, and everywhere in between. And not only can they live on land, but snakes swim very well across streams, and they can even live in the ocean. Snakes can be found on every continent except for Antarctica and in every country except for the island nations of New Zealand, Ireland, Greenland, and Iceland.
So what makes a snake a snake? Snakes don't have legs, so they move by relying on their incredibly muscular body as well as their extreme flexibility. Snakes can climb trees, burrow in the sand, swim across rivers, and wrap around my arm, and they can do all this without legs.
Because they are so flexible, people tend to think that they don't have any bones. But that's not at all true. Snakes are vertebrates just like you and I. All vertebrates have backbones consisting of vertebrae.
But where humans only have 33, snakes can have up to 200 to 400 vertebrae. With all those vertebrate, snakes can curve, bend, and twist in all sorts of ways are just impossible for humans. With this many vertebrate, snakes can stretch out, curl up into tight balls, tie themselves into knots, and even get into small, tiny spaces.
Because so many stakes are shiny, some people tend to think that they will feel slimy. But that's not the case at all. Snake skin is very dry and smooth. So when you're petting a snake, it kind of feels like a massage, because they're so sleek and smooth and flexible.
The smoothness comes from the thousands of tiny scales which cover and protest a snake's body as well as help them grip surfaces. One of the unique things that snakes can do is shut off their entire top layer of skin all in one piece. This shedding process is essential for growth. That's why young snakes tend to shed more often than older snakes-- because they are growing at a much faster rate.
You can tell when a snake is about to shed when the single clear, protective scales covering its eyes becomes cloudy and the colors of its scales aren't as vivid. Next, the snake will rub the corner of its mouth on a rough surface to start the shedding process. The entire snakeskin will shed off in one piece, just like a sock.
Snakes, just like all other reptiles, are ectothermic. That means that they depend on their outside environment to heat their body, and their body temperature adjusts to the temperature of their surroundings. Snakes use their senses to locate food, escape predators, and find mates.
Most snakes have pretty poor eyesight, so they rely on their other senses, such as their sense of smell. Did you ever wonder what a snake is doing when it's flicking its tongue out at you? It's actually using its tongue to smell.
Snakes use their tongue to smell by collecting small amounts of scent particles in the air around them. When they bring their tongue back into their mouth, it touches a structure known as a Jacobsen's organ. This specialized sensory organ translates the scent particles the snake picks up in its environment into signals the brain can interpret as smells. This gives them information on what kind of prey is around them and how close.
What's really cool is that snakes also have the ability to sense infrared heat through facial pits. This gives them a thermal radiation picture that allows them to see warm-blooded organisms in the dark. These heat-sensing pits are characteristic of pit vipers, pythons, and boas.
So what do snakes eat? The diet of most wild snakes consists of small rodents, other reptiles, insects, and fish. The smallest snakes can eat insect larvae or worms. On the other hand, the largest snakes can eat entire deer.
Snakes swallow their food whole. And even more incredibly, snakes can swallow food much larger than its own head. They have special jaw adaptations that allow them to do this.
You may have heard that snakes can swallow such large prey items because they can detach their jaws. However, that's not exactly true, and the snake's jaw is still connected to its skull. It just has extra bones on the side of its skull in order to help with extension and flexibility.
The bottom portion of a snake's jaw is also not fused together like it is in humans, allowing the snake's jaw to stretch to incredible sizes. Snakes can also move the two sides of their jaws separately to grab prey and pull it down, then to use the other side of the jaw to move. So their jaws pretty much can move independently of each other.
Strong body muscles helps the snake swallow and digest their meals. The throat takes up the first third of the snake's body. And once the prey passes through the throat, it enters the long, stretchable stomach.
Food items can stay in the digestive tract for long periods of time during the slow digestion process. The bigger the prey item, the longer it takes to digest. Digestion can take anywhere from a few days to up to a year, depending on the size of the meal, because snakes have extremely low metabolisms.
Large snakes don't need to eat as often as smaller snakes because they have the ability to consume much larger prey items. Some large snakes, such reticulated pythons, can survive up to a year without food after feeding.
Snakes have two unique approaches to killing their prey. The first is called constriction. It involves the snake wrapping its coils tightly around its prey until the blood flow is cut off from the brain. Constrictors have rows of small, sharp teeth that face the back of their mouth and act as fishhooks to lock in their struggling prey. Most calubrids, boas, and pythons are considered constrictors.
The second adaptation involves the use of venom. Venom is located in two glands in the head that connect to the snake's hollow fangs. Venomous snakes use their two long, hollow fangs like hypodermic needles to inject venom and quickly incapacitate their prey so the snake can have its meal.
There are only four types of venomous snakes in North America. They are copperheads, rattlesnakes, coral snakes, and cottonmouths. There are several characteristics to look for to determine if a snake is venomous or not in North America.
For example, venonmous snakes tend to have triangular-shaped heads due to the presence of venom glands, while non-venomous snakes will have a rounder shaped head. Next, venomous snakes usually have a pupil in the shape of an elliptical slit, while non-venomous ones will have round-shaped pupil.
However, there is an exception to this rule, as the highly venomous coral snake has round pupils. If you come across a snake and you're not really sure if it's venomous or not, be safe, and just look at it from a distance.
Regardless, the reality is only some snakes are venomous. Only about 20% of known species of snakes even have the potential to kill. Even more important is that snakes prefer to retreat when encountered and only become defensive if they're threatened. That's why most snake bites are received by people who try to disturb or capture a wild snake. When left alone, snakes present little to no danger to humans.
About 70% of snakes lay eggs, just like birds do. They lay their eggs in safe, warm places, like hollow logs, or they'll bury them in the ground. Unlike bird eggs, snake eggs tend to be soft and leathery.
Most species of snakes will lay their eggs in a safe spot and never return. The baby snakes later hatch from their eggs and are on their own. However, this isn't a problem for baby snakes, as they are perfectly capable of hunting for prey and hiding from predators immediately after hatching.
However, some snakes are great moms. Several species of pythons stay curled around their eggs and keep them warm and safe until they hatch. Some snakes, such as rattlesnakes and gardener snakes, give birth to live young. It has been recently discovered that some species of snake, such as boa constrictors and green anacondas, also give birth to live young, but their young are nourished through both the yolk sac and the placenta. This is very similar to mammalian reproduction.
So why should we care about snakes? What are they good for? Unfortunately, snakes are in trouble. They sometimes get a bad reputation, so they are often perceived as animals to fear and hate. That's why many snakes-- even the harmless ones-- are killed out of ignorance and fear.
Their populations have been declining due to human activity. Some snakes are caught and shipped around the world to be part of the exotic pet trade. Others are poached for their skin that is then made into fashion items, such as purses, belts, and shoes. Others are killed because people don't understand how important they are in reducing rats and mice and other pests.
But perhaps the most detrimental impact on snake populations everywhere is habitat destruction. Snakes are being driven out of their native habitats to make way for highways, agriculture, and industries. Pollution, deforestation, and introduction of invasive species have also had negative impacts on many snake populations.
Snakes are really important predators in many ecosystems. We don't want to find out what would happen in a world without snakes. Snakes are an important component of maintaining high levels of biodiversity.
Snakes also contribute to modern medicine, as the unique properties of snake venom are being studied for uses in cancer reduction therapies. But most importantly, snakes are fascinating and unique organisms that can't protect themselves against what we are doing to them and the environment. So it's up to us to help them.
I love keeping snakes. They are amazing animals, and you can learn so much from them. I always make sure to only purchase captive-bred snakes and avoid wild-caught ones. I also make sure to help teach others about how awesome and amazing these animals are.
Many snake species have adapted extremely well to living with humans. So it's about time that we adapt to live safely with them and realize that they are incredible creatures worthy of our respect and protection.
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What makes snakes so fascinating? Their diverse prey capture methods, their ability to live in many habitats, or their potential risks to humans? Here Morgan discusses all aspects of snake biology. Look carefully, those aren't all dreadlocks...