Doug Scull s Science and Nature

Transcription

1 THE SNAKES PART ONE Doug Scull s Science and Nature Feared by some, worshiped by others, snakes are some of the most misunderstood animals on Earth. Some people are fearful of snakes Some people worship snakes Without legs, snakes can slither, crawl, climb or swim. And they do these things with beauty and grace! There are more than 2,500 different species of snakes. You can find snakes just about everywhere, except Ireland, Iceland, New Zealand, the Arctic and Antarctica. Some are very small. The Thread Snake grows to 4-5 inches long. Others can grow to be over 30feet long. One Reticulated Python grew to be 33 feet- the longest snake ever recorded! A huge Reticulated Python Snakes bodies are covered with scales like all reptiles. The scales on the back and sides are small. Sometimes these scales overlap each other.

2 Belly scales are called scutes. They are bigger than the other scales. The scutes, along with the snake s skeleton and muscles, help the snake move. Water Snake s belly scales As a snake grows, it needs a new, roomier skin, so it sheds its old skin in one piece. When it is about ready to shed its skin, it usually stops eating and goes into hiding. The clear scales that cover the eyes, called spectacles, become cloudy and blue. The snake rubs the sides of its mouth against a rock or other rough surface. The old skin breaks and begins to come loose. The snake then continues rubbing and begins to wriggle away, leaving its old skin behind. Beneath the skin, a snake has strong muscles and hundreds of bones. Its backbone, or spine, is made up of more than one hundred bones called vertebrae. Attached to each vertebra are two ribs. Some snakes have 400 ribs, but we have only 24! Each rib connects to a belly scale, or scute. Snakes can move the ribs which move the scales that move the snake forward. Cool! Snakes have no ears but can feel vibrations through the ground and know when a human is approaching. They have excellent vision but their keenest sense is their sense of smell. Their tongues are used to smell with. Each time a snake flicks its tongue, it

3 picks up odors from the air or from the ground. When the tongue is brought back into the mouth it brushes against two cavities, or holes, in the upper mouth. These are called the Jacobson s Organ and it is here that the odors the tongue has picked up are deposited. The Jacobson s Organ has many sensory cells that are constantly sending messages to the brain about the odors the tongue has picked up. All snakes are predators, or hunters. After catching their meal, some snakes swallow their prey with out killing it. Snakes can swallow animals more than 3 times the size of their heads. They do this by stretching their mouths. If you could do this, you would be able to swallow a watermelon in one gulp! Garter Snakes, Water Water Snake swallowing big fish Snakes and Black Racers are a few that swallow their prey alive. Other snakes, called constrictors, wrap their bodies around their prey and squeeze. They do not squeeze hard enough to break the bones of the prey. They squeeze hard enough and long enough so that the animal cannot breathe and it suffocates. It is then swallowed whole. King Snakes, Rat Snakes and Boas are all constrictors. Finally, there is a group of snakes that have venom to kill their prey. Of the more than 2,500 species of snakes on Earth, only about 450 kill their prey by injecting venom with their teeth. Rattlesnakes, Cobras and Sea Snakes are some of the venomous. groups of snakes.

4 THE SNAKES WE MET IN THE VIDEO SNAKES- PART ONE The Chain King Snake is also called the Eastern King Snake. It is found over much of the United States and in Mexico. It is a strong constrictor and eats a variety of animals, including mammals, birds, amphibians and other reptiles. This snake is considered by many to be a friend of ours because they will eat venomous snakes, like the rattlesnake and the copperhead. If bitten by one of these nothing happens to the king snake, it is immune to their venom. They make excellent pets and become very tame. The Yellow Rat Snake is a large and beautiful harmless snake. They are powerful constrictors that feed on mammals, birds and bird eggs. They will also eat any frog they can catch. Because they are often found in chicken coops looking for an easy meal, they are also called the Chicken Snake. Many people keep these snakes as pets. They have bred in captivity for years. Some breeders, through selective breeding, have bred a number of different color varieties.

5 The Common Boa Constrictor is a large snake from northern Mexico to South America. They usually do not get longer than 10 feet, however one from the Island of Trinidad was 18 feet long! They can be found in many types of habitats including rain forests and arid land. Small, young boas seem to prefer living in trees. As the snake gets older and larger it spends more time on the ground. Boas eat mammals, birds and lizards. These are commonly kept as pets. Just remember before buying a baby boa for a pet, it will grow big! The Cook s Tree Boa is from the South American rain forests. It can grow to 6 feet long but it has a very thin body. Its body allows it to move effortlessly through the tree branches it lives on. It is rarely found on the ground. These boas eat mammals, like bats and birds. Their long teeth can penetrate a bird s feather. These snakes are not recommended as pets. They do not tame down and will bite anyone or anything too close. The Burmese Python is one of the world s largest snakes. Females can grow to over 20 feet long and weigh over 200 pounds! Males average length is around 15 feet. These snakes are native of Southeast Asia. They are equally at home on land as in trees. They are also excellent swimmers. In Asia, they are frequently hunted and killed for their skins and internal organs. Their numbers in the wild are dwindling and they are protected in many countries. Burmese Pythons found in the USA are almost always ones that have been bred here. They usually are gentle giants, however there are reports of pet owners being killed by these snakes. Not recommended as pets; they get big!