Reptiles are among the fascinating creatures on Earth. They have existed much before human life began. Astonishing as it may sound, there are about 9,547 identified species of reptiles in the world. In a broad sense, they can be classified as:
Today, many cities around the world host events and exhibitions to educate people about reptiles and spread awareness about their conservation status. October 21 is celebrated as Reptile Awareness Day.
- Reptiles are found on every continent of the world, except Antarctica, which is not surprising, considering that they are cold-blooded animals which cannot regulate body temperature on their own. Instead, they rely on external temperature for the same.
- Reptilian species have existed on Earth for more than 300 million years now. It may come as a surprise for some, but dinosaurs were also reptiles. (And even though the word 'dinosaur' means terrible or mighty lizards, dinosaurs were not 'lizards' as many people believe.)
- One gets to see a great deal of diversity in class Reptilia, with at least 327 species of turtles, 25 species of crocodilians, 3,378 species of snakes, 2 species of tuataras and 5,634 species of lizards to its credit. Serpentes (snakes) and Lacertilia (lizards) are the two suborders of order Squamata.
- As reptiles breathe through the lungs, they cannot breathe underwater. Species of turtles and crocodiles need to resurface at regular intervals to breathe. Only a few reptiles can absorb oxygen in water through membranes in their mouth.
- Most reptiles lay eggs which have leathery shells that are resistant to drying. Only a few species are viviparous, i.e., they give birth to live young ones. Some reptiles resort to internal fertilization and don't lay their eggs in water.
- All the reptiles, except for the crocodilians, have a three-chambered heart with two atria and one ventricle. In case of crocodilians, the heart is four-chambered, which may have something to do with their endothermic ancestry. In comparison to amphibians, reptiles have advanced circulatory, respiratory, excretory, and nervous systems.
- Reptiles found in cold regions are known to hibernate (wherein they seek shelter in burrows or beneath logs) in winter. Similarly, reptiles found in very hot or dry climates resort to aestivation, or go into a torpor, in summer.
- Reptiles have scales or horny plates covering their body which are made of keratin, a fibrous scleroprotein which is also found in our fingernails. These scales are replaced periodically, either by means of dry flaking or skin shedding.
- Most reptiles are carnivores feeding on insects, amphibians, other reptiles, and small mammals. Only a few species are known to feed on plants. Interestingly, the sea turtle hatchlings are carnivorous in nature, but as they grow they shift to a herbivorous diet.
- In most reptilian species, the young ones are left to fend for themselves from the moment they enter the world. While a female crocodile at least hangs around with the newborns for a certain period, the female sea turtles never come back to the shores. The turtle hatchlings are expected to make it to the water on their own, and that while fighting scores of predators.
- Snakes have a very flexible jaw which helps them swallow prey animals that are much larger than themselves.
- The Black mamba is considered as the fastest and deadliest snake in the world.
- The longest snake is the reticulated python and the heaviest is the anaconda.
- Boa constrictors are non-venomous snakes that squeeze their prey to death. They are mainly found in South and Central America, where they are often used to control rat plague.
- Brown House snakes are also non-venomous snakes, commonly found in southern Africa. The animals they prey on include rats, mice, frogs, lizards, and birds. They kill their prey by crushing it in their coils.
- Snakes don't have limbs. They move by slithering along the ground. In the Australian continent, there are more venomous snakes than the non-venomous ones.
- Some snakes are venomous. They have fangs with which they bite and inject venom into their prey.
- Snakes such as anacondas and reticulated pythons can survive for months without eating.
- It is not exactly clear whether snakes have evolved from marine or terrestrial ancestors, and the recently found fossil of Najash rionegrina (in Argentina) has only fueled the ongoing debate. The remains reveal that the species, believed to have lived around 90 million years ago in Patagonia, had a sacrum and pelvic girdle.
- If a snake is born with two heads, both its heads fight each other for food.
- A frilled lizard when threatened, opens its mouth and pleated frills wide, and makes a sharp hissing sound.
- Green Basilisk Lizards are mainly found in the tropical rainforests of Central America. They are commonly seen on trees and are excellent swimmers. To avoid danger basilisk lizards run rapidly across the water.
- Komodo dragons are the heaviest and the deadliest predators. They have a very good sense of smell, can move very fast, climb trees and even swim. They feed on deer, pigs, water buffaloes and even humans. Thousands of toxic bacteria live in their mouth, with which they infect and poison their prey's blood causing them to die.
- Common lizards can do both - lay eggs as well as give birth to "live" young ones. When threatened they drop themselves into water or trick the predator by getting rid of their tail. A new tail begins to regrow but lacks its original color and pattern.
- Geckos are the most colorful lizards in the world. Their tail is similar to that of a crocodile. The tail and feet help them climb trees or other surfaces.
- Gila Monsters are the largest venomous land lizards found in the U.S. Their saliva has a synthetic version of protein which is believed to be beneficial for the treatment of diabetes in human beings.
- Certain lizards, such as the chameleon, can change colors to blend into their environment. This act of camouflaging is a behavioral adaptation seen in these species. It protects them from predators.
- Short-horned lizards, also known as Horned Toads, feed primarily on ants, beetles, spiders, and grasshoppers. When threatened they are capable of shooting blood from their eyes. They can expand their bodies to twice the original and scare hungry predators away.
- Green Iguanas - mainly found in rainforests of Central America - feed on leaves, insects, fruits, worms, and flowers. They also possess a parietal eye (third eye) which helps them sense light. The loose flap of skin under an iguana's chin is called a dewlap which is used to warn or signal other iguanas.
Turtles and Tortoises (Testudines)
- Many giant tortoises (Geochelone) have lived for 120 to 150 years. Interestingly, turtles were present on earth before the dinosaurs.
- Chaco tortoises are small-sized tortoises, an endangered species found basically in Argentina and Paraguay. They are believed to be the closest relative of the Galapagos tortoise.
- Alligator Snapping Turtles are one of the largest freshwater turtles, an endangered species with a prominent beak-type jaw, spiked shell, and a scaled tail.
- Green Sea Turtles are called so because their fat is greenish in color. They are large sea turtles with a heart-shaped shell. They feed on jellyfish and shrimp.
- To keep their enemies away, the female turtle first digs many empty nests before laying her eggs.
- Turtles cannot come out of their shells as they are built into their skeleton. Nerve endings help them sense things.
- Sea turtles cannot pull their head and legs inside their shell.
- Whether they live on land or sea, all turtles lay their eggs on land. Many female leatherback sea turtles return to the same nesting area where they were born, to lay their eggs.
- Africa has the largest number of land turtles or tortoises than any other continent.
- The difference between a turtle and tortoise is that they can grow up to four feet long and they are the slowest of all turtles. Unlike sea turtles, a tortoise can hide inside its shell. And they live only on land.
- They are the only reptiles that have a shell and are considered one of the oldest reptile group ever.
Alligators and Crocodiles (Crocodylia)
- The largest reptile is the saltwater crocodile, which grows up to 23 feet in length and is an excellent swimmer. It has the ability to grow new teeth to replace the old ones.
- The American crocodiles can tolerate high levels of salinity. They feed on snakes, frogs, turtles, and smaller mammals.
- In 2000 B.C. for the first time in human history, crocodile dung was used as a contraceptive by the Egyptians.
- The most aggressive, voracious and second-largest crocodile in the world is the Nile crocodile. It attacks those animals which come to drink water (their prey includes large cats, camels, donkeys, buffaloes, zebras, young hippos and so on).
- A crocodile cannot stick its tongue out.
- The difference between an alligator and a crocodile is that when an alligator closes its mouth only the upper teeth are visible, whereas when a crocodile closes its mouth both its upper and lower teeth are visible. Alligators have rounded snouts and crocodiles have long, pointed snouts.
- Alligators' heads are shorter and wider than those of crocodiles and they have a really small brain - the size of a lima bean. An alligator will eat anything that moves, literally anything that they can get their powerful jaws on.
- Alligators have two sets of eyelids that protect their eyes and help them see more clearly under water.
- Alligators are cold-blooded reptiles that can go on for a few years without eating. They have an ability to store extra fats at the lowest part of their tails and live off these fat reserves.
- Crocodiles and alligators build a nest and lay about 30 to 60 eggs. The egg incubation period takes about 40 days to 3 months and the sex of the baby crocodilia depends on the temperature of the nest.
- Although tuataras may resemble a lizard they are not the same. They are beak-headed reptiles, carnivores that relish on moths, crickets (weta), beetles, lizards, eggs, worms, snails, baby birds and even other tuataras.
- Tuataras are nocturnal reptiles, active mostly at night and commonly found in the remote rocky islands of New Zealand.
- A tuatara lays about 8 to 10 eggs. Studies show that chances of these eggs turning out to be male or female depend on the intensity and climate conditions of the soil. If the soil is warm, male tuataras are hatched and if the soil is cool female tuataras are born.
- Tuatara eggs take eleven to eighteen months for incubation. Unfortunately, this gives predators an opportunity to hunt them.
- Just like iguanas, a young hatchling of tuatara also possesses a third eye (parietal eye) on top of its head between other eyes. They get enclosed once the tuatara becomes an adult.
- The prominent feature of a male tuatara is its crest of spines and its size. They use this to attract a female tuatara and also demonstrate it in an aggressive manner while fighting.
- Tuataras are amazing creatures, they grow very slowly and can live up to 100 years.
- Young hatchlings develop a spike on the tip of their nose known as 'egg tooth'. They use it as a tool to break the egg and come out. After a few weeks, this egg tooth disappears.
- The unique feature of a tuatara is that it has a very good eyesight, an elongated tail, no ears, and its body temperature varies with the environment.
Reptiles are an integral part of the ecosystem and therefore, it is our responsibility to preserve them in their natural habitat.