Category Nature Science & Wildlife

There are four orders of reptile, by far the largest of which is the order of lizards and snakes. There are nearly 6000 different species of these. The other orders are much smaller. There are about 200 species of turtles, tortoises and terrapins, and only just over 20 species of crocodiles and alligators. Rarest of all is the tuatara, which forms an order all by itself.

Reptiles are tetrapod animals belonging to the class Reptilia, which includes turtles, snakes, crocodilians, tuatara, lizards, and amphisbaenians. Reptiles likely originated more than 312 million years ago, when the first species evolved from the advanced reptiliomorph tetrapods. Today, animals belonging to class reptilian range in size from tiny geckos to huge saltwater crocodiles that measure more than 19 feet in length. There are approximately 10,700 extant reptile species.

The Reptile Database is a database that lists all living reptiles and their classifications. It also contains images for most reptiles on the list. There are more than 10,700 extant species of reptiles recorded in the Reptile Database, making reptiles one of the most diverse types of vertebrates in the world. Compared to other species, only birds and fish have more types of species than reptiles. Additionally, there are approximately 5,000 and 7,000 species of mammals and amphibians, respectively.

Reptiles form part of the domain Eukaryote, which consists of organisms that have a nucleus within membranes. They are also included in the kingdom Animalia, which are organisms that ingest food and are multicellular. Reptiles are further classified as Chordate because of the presence of a spinal cord running the length of their back. As Chordate with backbones, they belong to subphylum Vertebrata and class Reptilian. There are four major groups of reptiles: Crocodilian, Squamata, Sphenodonita, and Testudines.

Crocodilia

The order Crocodilian is a subclass of Archosauria and contains some of the largest reptiles including crocodiles, caimans, alligators, and gavials. Reptiles in this order are mainly carnivores and typically inhabit tropical and subtropical rivers, swamps, and streams. They have strong jaws which facilitate a powerful bite, advanced brains, and greater intelligence than other reptiles.

Squamata

The Squamata order contains terrestrial reptiles such as snakes and lizards. There are approximately 3,750 species of lizards and 3,000 species of snakes. These animals have the ability to crawl or creep using their abdomen. They possess skin covered with horny scales that are periodically shed. Although snakes do not have legs, they evolved from four-legged ancestors.

Sphenodontia

Sphenodotia is the least specialized group of reptiles, with brains similar to those of amphibians. The best-known sphenodontite is the tuatara, which is a species that has a wedge-like skull with primitive eyes and socketless teeth. The lizard-like creature lives primarily in New Zealand.

Testudines

There are approximately 250 species belonging to the order Testudines, which are primarily turtles and tortoises. The species are four-legged and have a hard shell covering most parts of the body. They are mainly aquatic and are the oldest living reptiles in the world.

          Amphibians have a wide range of ways of protecting themselves. Some brightly coloured amphibians produce poisons in glands on their skins. The bright colours warn birds and animals not to attempt to eat them. Others use camouflage, blending with their surroundings, to prevent enemies from spotting them. Some frogs and toads puff themselves up or stand on tiptoes to look larger than they really are!

          Frogs, salamanders, snakes, and other herps are often small and live on the ground or in the water. Because of these characteristics, they are vulnerable to being preyed on by all kinds of carnivorous animals. In order to avoid being eaten, herps use a variety of strategies and protective mechanisms. As a first line of defense, most herps try to avoid being seen by their predators. Many are nocturnal and use the cover of darkness to avoid notice. During the day, most herps tend to remain hidden beneath dead leaves, rocks, and logs, or in underground burrows.

          Herps also avoid confrontation through camouflage. Using a variety of grays, greens, and browns, these animals can blend remarkably well into the background of their natural environment. It is amazing how difficult it is to see a smooth green snake that is moving through the grass!

          Countershading is an interesting form of camouflage for herps that live in the water. Many turtles, frogs, and salamanders have light colors on their bellies and dark colors on their backs. This color pattern makes them less visible to aquatic predators that see them against a light sky. Birds and other predators hunting from above also have a hard time spotting them against the dark water. Even some of the larger predators, such as snapping turtles and alligators, have countershading, perhaps to be less visible when stalking their prey.

          A lot of species use spots, stripes, and blotches to break up the outline of their bodies when viewed against leaves or soil. The distinctive “x” on the back of the spring peeper is an example of a mark that allows this frog to virtually disappear when on the ground or perched on a blade of grass. Unlike animals that use camouflage, the colors of these animals do not necessarily blend with the background. In fact, many times the markings are quite bright and even gaudy. The eyes of the predator, however, are tricked into thinking the shape they are seeing is not an animal.

          Some herps do not avoid or hide from predators, but instead frighten them off by displaying warning signs. For example, toads and newts have glands in their skin that produce toxins. In order for this toxicity to protect an animal from being eaten, the predators must be reminded that they are about to eat something that will make them sick. A common method of alerting a predator is by being very brightly colored. This explains why the young newts, or efts, that we see walking around the forest are bright orange and yellow. Their color is a vivid advertisement of their toxicity. Other common examples of this aposematic, or warning, coloration are the brightly banded, venomous coralsnakes and the very decorative, poison dart frogs of Central America.

          Interestingly, a herp truly may be poisonous or it may be just bluffing. Some harmless herps have adapted their appearance to mimic that of a more poisonous relative. In this way, they take advantage of markings that bring back unpleasant memories for predators. Such mimicry may protect the brightly colored, red-backed salamander from would-be predators, even though it is not toxic like the similarly colored eastern newt. Some snakes also mimic their poisonous relatives as a means of defense. The nonpoisonous scarlet king snake looks remarkably like the venomous coral snake, both of which are found in the same region.

          Finally, many herps scare off potential predators with threatening postures orbehaviors. Snapping turtles, when encountered on land, can be very aggressive, snapping their jaws and lunging. Probably the most notorious warning among herps is the very d a nearby rattlesnake is enough to make most animals halt in their tracks and mistinctive and chilling sound of a rattlesnake’s tail. The mere suggestion of ake a hasty retreat. Some snakes will rise up as if poised to strike an attacker. This act also has the advantage of making them appear larger and perhaps more threatening.

          The hog-nosed snake, a common resident of the coastal plain, uses a complicated set of behaviors when it is attacked. It first elevates its head and spreads out the skin of its neck in an effort to look bigger and more threatening. If this doesn’t scare off a predator, the hog-nosed snake begins to writhe upside down. It then regurgitates a foul smelling liquid and finally becomes rigid. It holds this position for several minutes, until the predator becomes disinterested and moves off.

          The red-eyed tree frog lives in the rain-forests of South America. Although it can swim, it spends much of its life out of water, among the leaves of trees where there are plentiful insects for food. The tree frog’s toes have sticky pads that enable it to grip branches as it climbs.

          Tree frogs are a diverse family of amphibians that includes over 800 species. Not all tree frogs live in trees. Rather, the feature that unites them has to do with their feet—the last bone in their toes (called the terminal phalanx) is shaped like a claw. Tree frogs also have toe pads to help them climb and many have extra skeletal structures in their toes. Tree frogs can be a variety of colors, but most of the species found in the United States are green, gray, or brown. Some of them, like the squirrel tree frog (Hyla squirella), are chameleon-like in their ability to change color.

          Although tree frogs can grow to be a range of sizes, most arboreal species are very small because they rely on leaves and slender branches to hold their weight. At 4 to 5.5 inches (10 to 14 centimeters) long, the white-lipped tree frog (Litoria infrafrenata) from Australia and Oceania is the largest tree frog in the world. The largest tree frog in the United States is the non-native Cuban tree frog, which reaches 1.5 to 5 inches (3.8 to 12.7 centimeters) in length. The world’s smallest tree frogs are less than an inch (2.5 centimeters) long!

          Tree frogs are found on every continent except Antarctica, but they’re most diverse in the tropics of the western hemisphere. About 30 species live in the United States, and over 600 can be found in South and Central America. Not surprisingly, lots of tree frogs are arboreal, meaning they live in trees. Special adaptations like toe pads and long legs aid them in climbing and jumping. Non-arboreal tree frogs find habitats in lakes and ponds or among moist ground cover.

          Tree frogs are consumed by many different carnivorous animals. Mammals, reptiles, birds, and fish all eat tree frogs. Many of the frogs rely on camouflage to protect themselves from predators, and the more arboreal species escape ground-dwelling predators by hiding in trees. Adult tree frogs are insectivores that eat flies, ants, crickets, beetles, moths, and other small invertebrates. However, as tadpoles, most of them are herbivores.

          Almost all male frogs attract mates with advertisement calls. Each frog species has its own call so female frogs can listen for potential suitors of their own species. The frog call that most people are familiar with—“Ribbet!”—belongs to the Baja California tree frog (Pseudacris hypochondriaca). The ribbeting call has been incorporated into outdoor scenes of many Hollywood movies, even outside of the frog’s range.

          Some frogs hatch as miniature adults. More commonly, however, tadpoles emerge from frog eggs. As tadpoles mature, they lose their tail and grow legs until they eventually reach their adult form. The lifespan of tree frogs varies among species. Some of them are long-lived, such as the Australian green tree frog (Litoria caerulea), which is often kept in captivity for upward of 15 years. Species with lifespans of less than three years are considered short-lived. North America’s gray tree frogs (Hyla versicolor and Hyla chrysoscelis) are somewhere in the middle with a lifespan of five to nine years.

Picture Credit : Google

          In ancient times, it was believed that salamanders could live in the middle of fires, as the cold of their bodies extinguished the flames around them. Of course, this is quite untrue, but the story may have come about because salamanders were often seen to run out of logs thrown onto the fire.

          In the first century AD, Roman naturalist Pliny the Elder threw a salamander into a fire. He wanted to see if it could indeed not only survive the flames, but extinguish them, as Aristotle had claimed such creatures could. But the salamander didn’t … uh … make it.

          Yet that didn’t stop the legend of the fire-proof salamander (a name derived from the Persian meaning “fire within”) from persisting for 1,500 more years, from the Ancient Romans to the Middle Ages on up to the alchemists of the Renaissance. Some even believed it was born in fire, like the legendary Phoenix, only slimier and a bit less dramatic. And that its fur (huh?) could be used to weave fire-resistant garments.

          Part of the problem, it seems, is that in addition to disproving the salamander’s powers, Pliny also wrote extensively that it had such powers—and then some. His Natural History, which has survived over the centuries as a towering catalog of everything from mining to zoology, describes the salamander as such: “It is so chilly that it puts out fire by its contact, in the same way as ice does. It vomits from its mouth a milky slaver [saliva], one touch of which on any part of the human body causes all the hair to drop off, and the portion touched changes its color and breaks out in a tetter,” a sort of itchy skin disease.

          Some 500 years later, Saint Isidore of Seville wrote that while other poisonous animals strike their victims individually, the salamander slays “very many at the same time; for if it crawls up a tree, it infects all the fruit with poison and slays those who eat it; nay, even if it falls in a well, the power of the poison slays those who drink it.” He also confirmed that it’s immune to the effects of fire.

          So right away the salamander was mythologized as both a miraculous survivor and a menace. Indeed, later on in the 1200s, an English writer told of one laying waste to Alexander the Great’s army simply by swimming in a river they drank from. All told, 4,000 soldiers and 2,000 horses supposedly perished after consuming the salamander’s dirty bath water. Which would be pretty embarrassing, if only it were true.

          Now, it was likely Europe’s fire salamander, with its vivid yellow-on-black coloration, that served as the inspiration for the legend, according to Nosson Slifkin in his book Sacred Monsters. As you might assume from its conspicuous colors, this species is in fact quite poisonous, secreting a neurotoxin to deter predators. And if it doesn’t feel like waiting to be attacked, it can actually fire this secretion at its approaching enemies. While the toxin can cause skin irritation in humans, it’s far from capable of poisoning 4,000 soldiers. But it’s likely this poisonous nature was simply scaled up for such myths.

          A few centuries later, none other than Leonardo Da Vinci added another curious characteristic to the salamander’s repertoire, claiming it “has no digestive organs, and gets no food but from the fire, in which it constantly renews its scaly skin.” The alchemist Paracelsus later confirmed this as its diet, elevating the salamander to the status of one of the four “elementals” that he substituted for the classical elements earth, fire, air, and water—the salamander of course being fire.

          Most amphibians lay their eggs in water. Frogs’ eggs are called spawn. They are protected from predators by a thick layer of jelly. Inside this a tadpole develops. When it hatches out, it is able to swim, using its long tail, and breathes through gills. As the tadpole grows, first hind legs and then fore legs begin to grow. Lungs develop, and the young frog is able to begin to breathe with its head above water. Gradually, the tail shortens until the young frog resembles its adult parents.

          In typical amphibian development, eggs are laid in water and larvae are adapted to an aquatic lifestyle. Frogs, toads, and newts all hatch from the eggs as larvae with external gills but it will take some time for the amphibians to interact outside with pulmonary respiration. Afterwards, newt larvae start a predatory lifestyle, while tadpoles mostly scrape food off surfaces with their horny tooth ridges.

          Metamorphosis in amphibians is regulated by thyroxin concentration in the blood, which stimulates metamorphosis, and prolactin, which counteracts its effect. Specific events are dependent on threshold values for different tissues. Because most embryonic development is outside the parental body, development is subject to many adaptations due to specific ecological circumstances. For this reason tadpoles can have horny ridges for teeth, whiskers, and fins. They also make use of the lateral line organ. After metamorphosis, these organs become redundant and will be resorbed by controlled cell death, called apoptosis. The amount of adaptation to specific ecological circumstances is remarkable, with many discoveries still being made.

          Egg Stage: Amphibian eggs are fertilized in a number of ways. External fertilization, employed by most frogs and toads, involves a male gripping a female across her back, almost as if he is squeezing the eggs out of her. The male releases sperm over the female’s eggs as they are laid. Another method is used by salamanders, whereby the male deposits a packet of sperm onto the ground. The female then pulls it into her cloaca, a single opening for her internal organ systems. Therefore, fertilization occurs internally. By contrast, caecilians and tailed frogs use internal fertilization, just like reptiles, birds, and mammals. The male deposits sperm directly into the female’s cloaca.

          Larval stage: When the egg hatches, the organism is legless, lives in water, and breathes with gills, resembling their evolutionary ancestors (Fish). During the larval stage, the amphibian slowly transforms into an adult by losing its gills and growing four legs. Once development is complete, it can live on land.

          Toads and frogs are similar in many ways, although toads usually have rougher, drier skins and may waddle rather than hopping as frogs do. Some toad spawn is produced in strings, like necklaces, rather than the mass of eggs laid by a frog. While these little amphibians might look very similar at first glance, there are actually a plethora of key differences between them. Frogs and toads may seem similar, but they are quite different. There are many physical differences, such as differences in skin, color, and body type. There are also differences in behavior. A frog will need to be in close proximity to a body of water, for instance, while a toad can be further away. Frogs also tend to hop higher than toads.

          If there was ever a tell-tale sign to indicate which amphibian you are looking at, it’s the texture of their skin. Toads are warty-looking, covered in little lumps and bumps, while Frogs are sleek and smooth. Toads also virtually always have dry skin, whereas frogs look wet even when they are out of the water.

          If you’ve spotted an amphibian making its way along a pavement or ambling through some grass, chances are it’s a toad. Toads cope much better with dry conditions than frogs, as their skin is more waterproof. Frogs lose moisture a lot more easily, and so are rarely seen too far away from water, which explains why they always look moist.

          Frogs have long legs, longer than their head and body, which are made for hopping. Toads, on the other hand, have much shorter legs and prefer to crawl around rather than hop. Frogs are lithe and athletic-looking, whereas toads are somewhat squat and dumpy. Their faces are different too; frogs have a pointed nose while toad noses are much broader. Spawn is another key indicator for which species you’re looking at. Frog spawn is laid in gooey clumps, whereas toads spawn floats in stringy lengths. Like their adult counterparts, frog tadpoles are slimmer whereas toad tadpoles are chunky. Frog tadpoles are also covered in gold flecks, while toad tadpoles are plain black in colour.

Picture Credit : Google