Reptile species are the largest, most diverse group of cold-blooded, air-breathing vertebrate animals. Unlike mammals and birds, their skin is not furry and they have scales or bony plates.
Their highly developed lungs enable them to breathe the air around them. Some, such as the lizard-like tuatara of New Zealand, have dinosaur ancestors; others, like alligators and caimans, are close relatives to birds.
Snakes (suborder Serpentes, order Squamata) are limbless reptiles with an elongated body and tail. They are carnivorous, with eyes that never close and a forked tongue to taste the air. Their long slender bodies allow them to swallow prey much larger than their heads. Snakes have no voice or external ears, but they can hiss to communicate. They have a clear membrane over their eyes called a brille, and shed their skin at regular intervals.
Snakes range in size from a worm to many feet in length. Their skin is covered with supple, living scales. They have staring eyes that never blink or close, and a flickering forked tongue to seek and kill prey. They can be found throughout the world, in all climates and habitats, from tropical rainforests to deserts.
Some snakes, such as the reticulated python and green anaconda, are constrictors, which use their powerful bodies to kill prey by suffocating it. Other snakes, including venomous species such as the cobra and king cobra, use their teeth to bite prey. Like other reptiles, snakes are inactive during the cool months and rely on external heat sources to maintain their body temperature. They eat a variety of small animals such as insects, birds, mammals, and lizards. Most snakes lay eggs, but a few, such as the reticulated phoenix and paradise tree-snake of Southeast Asia, give birth to live young.
Lizards have an amazing ability to camouflage themselves or blend in with their surroundings. They can even change color to match their environment, a trick they use to fool predators. They also display a great deal of behavioral flexibility and are popular in the pet trade.
Unlike mammals and birds, reptiles are poikilothermic and can’t regulate their internal body temperature. They depend on external sources of heat to warm them up and cool them down, basking in the sun or hiding under a rock to get warmer and swimming in water to cool themselves off. In cold conditions, lizards become sluggish and can enter a state of torpor or brumation (similar to hibernating) for several months.
Many lizards use a special breathing technique called “buccal pumping” to inhale air. The process involves closing the nostrils, opening the glottis, moving the floor of the mouth up and down to compress and deflate the lungs, and then reversing the process to expel the air. This saves energy and helps lizards breathe at higher speeds than mammal species, which require a more complex thoracic diaphragm to inflate and deflate the lungs.
If a lizard is grabbed by a predator, it can break off or drop its tail to escape. It can then regrow its tail, though the new one may not look exactly like the old one. Scientists have learned that lizard tails have a weak spot designed just for this purpose.
While some people confuse alligators with amphibians because they both share some similarities, such as being cold-blooded and laying eggs, the two reptile species are very different. The main difference is that amphibians reproduce by external fertilization, whereas alligators have internal fertilation. Also, alligators have rounded snouts that stick up at the end, and this allows them to breathe air through the snout even while the rest of the body is submerged.
Alligators are long-lived reptiles that can live for more than 60 years. They can grow to more than 12 feet in length, and males are slightly larger on average than females. Their dark skin is armored with small, bony plates called osteoderms or scutes.
When female alligators lay eggs, they stay near the nest for a 65-day incubation period to protect it from predators and other dangers. Once the eggs hatch, the female keeps an eye on her babies to make sure they are safe and secure until they grow large enough to head off on their own.
Alligators are powerful, apex predators that provide important natural resources for other wildlife by helping to control the population of smaller animals and by digging holes that hold water during droughts. However, they can be problematic for humans as well, and human interactions with these prehistoric-looking creatures have been known to lead to fatal accidents.
Turtles have an incredible ability to adapt to different environments. While most turtle species are aquatic, ranging from small ponds to oceans, some are strictly terrestrial (tortoises) and others divide their time between land and water. The most defining characteristic of turtles is their shell, which protects them from predators. They also have a variety of behaviors, including basking to regulate body temperature and diving to forage.
The turtle’s shell is composed of 59 to 61 plates, or scutes, that cover the turtle’s spine and ribs. These scutes are covered by hard keratin scales that look like fingernails. Unlike amphibians, turtles cannot breathe through their skin, but they can feel pressure and pain through the shell.
They are considered one of the oldest and most primitive reptile groups and can be found in the wild all over the world except Antarctica. They are omnivorous, with some species such as the cooter eating mollusks and plants while others like the musk turtle rely on insects for food.
Interestingly, turtles are not social creatures. Males and females are primarily distinguished by size, with the largest males being more likely to mate with females of the same species, a practice known as sexual dimorphism. Most turtles spend their days foraging for food, but they are able to defend themselves by snapping their heads backward, similar to how snakes do.