Reptiles: Different Types, Definitions, Photos and More

Lizards, dinosaurs, crocodiles, turtles, and snakes—all belong to the ancient, stout class of animals known as reptiles. This is a diverse group with more than 10,000 different species that feature prominently in the fossil record. Once the dominant terrestrial vertebrates on Earth, reptiles still occupy nearly every ecosystem beyond the extreme north and south.

8 reptile traits – list

Most importantly, reptiles are an evolutionary classification. Each species in this category has a common ancestor dating back more than 300 million years. But it also has a set of common characteristics. At a basic level, all reptiles have four legs, or are descended from four-legged creatures (including snakes, which apparently still carry some genes for making legs). They are also vertebrates, with a backbone that houses the spinal cord. Additionally, most reptiles have the following characteristics:

  • Rough Scale – The skin of reptiles is covered with rough scale cuticles, bony plates, or a combination of both. These scales are made of keratin, the same substance found in nails, hair and claws. The skin is actually much thinner than you might think because it lacks the same layer of dermis as mammals. But waterproof skin does allow reptiles to survive and thrive in dry ecosystems.
  • Regular Shedding – Reptiles shed their skin continuously throughout their lives. Shedding tends to be most common during puberty because the skin doesn't actually grow in proportion to the body. Once the reptile becomes an adult, the frequency of shedding decreases. At this point, it's mostly about keeping your body healthy.
  • Cold-blooded animals – Reptiles have an inherently low metabolic rate, which helps conserve energy, but also means they lack any internal means of keeping their body temperature constant. Without fur or feathers to insulate, reptiles cannot keep warm in frigid temperatures. Without sweat glands, they also cannot stay cool in the heat. To compensate, they rely on sunlight or shade to alter their internal temperature as needed. Leatherback turtles are the only reptiles with elements of a warm-blooded physiology.
  • Spawning eggs – With the exception of some snakes and lizards, which lay live young, all reptiles are oviparous and lay their eggs in nests. The soil temperature at this time determines whether the pups are born male or female. Asexual reproduction is very rare, but known to occur in some lizards and snakes.
  • Highly developed lungs – All reptiles rely on lungs to breathe air. Even species with permeable skin and other adaptations cannot breathe fully without using their lungs.
  • Short digestive tracts – With a few exceptions, reptiles are carnivores with relatively short digestive tracts. Because of their slower metabolism, they can digest food slowly and eat smaller meals. In the most extreme cases, crocodiles, pythons and other reptiles can survive for months on a single meal. Herbivorous reptiles do exist, but they face a problem: Because they don't have any complex dental system, they have to swallow rocks and pebbles to grind up plant matter in their digestive system, like some birds do.
  • Chemosensory – Many but not all reptiles have chemosensory organs on the top of the nose or mouth to identify prey. This ability supplements and even replaces the sense of smell. Snakes in particular can sense chemicals in the air by quickly sticking out their tongues. This has the effect of moving odor particles from the tongue to the roof of the mouth.
  • Skull Morphology – Several features of the skull distinguish reptiles from other kinds of animals. For example, they have only one bone (the skull connects to the first vertebrate), one auditory bone (the stapes) that transmits vibrations from the eardrum to the inner ear, and a very strong jaw. An interesting aspect of reptilian morphology is that some of these jaws actually correspond to the two ear bones of mammals. It is believed that at some point in the evolution of early mammals, these jaws moved to the back of the head and eventually formed the malleus and incus in mammalian ears to aid in hearing higher frequency sounds.

Exceptions to oviparous reproduction

As mentioned earlier, reptiles primarily reproduce by laying eggs, or laying eggs, but there are some notable exceptions. About 20 percent of lizards and snakes, including pythons, do lay live young instead of eggs. These viviparous reptiles have a non-mammalian placenta or some other means by which nutrients are transferred from mother to offspring and vice versa. The main advantage of viviparity is that it protects the eggs from predators in a hostile environment. But there is a tradeoff with this method of delivery, as it places a burden on the mother.

Only three reptile species, including Australia's yellow-bellied three-toed skink, actually combine egg and live birth methods (a rarity that suggests evolution may have worked against this intermediate stage). The skink's offspring begin life in eggs, like any other reptile. But as the embryo develops, the egg begins to thin until it is born with only a small membrane remaining. The main problem with this method is that there is not enough calcium in the thin eggshells to nourish the offspring. Mothers seem to compensate for this by secreting calcium from the uterus so that it can be taken up by the developing embryo. Evidence suggests that skinks may choose to lay eggs weeks earlier if the danger to offspring seems less. In harsher climates, mothers will keep their offspring inside for longer to protect them.

Cloning is also fairly rare, although more common than live spawning. About 50 species of lizards and one species of snake participate in this breeding method. Evidence suggests that these reptiles may have adopted a sexless lifestyle out of necessity — because they were genetically isolated from the rest of the group. The problem with asexual reproduction is the lack of genetic variability: offspring inherit the same disease susceptibility as their parents. But asexual reptiles seem to maintain genetic variation by starting the reproductive process with twice the normal number of chromosomes.

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Four orders of reptiles

Modern reptiles are generally divided into four distinct orders, each with its own unique characteristics and morphology.

Testudines – As the only order classified within the subclass Anapsida, Testudines consist of all known species of turtles. Its main distinguishing feature is a hard cartilaginous shell extending from the ribs, which acts as a protective shield. Terms such as turtle, tortoise, and terrapin are based on local dialects and do not represent any specific taxonomic or biological differences.

Squamates – the youngest reptiles also happen to be the most common. It consists of most reptiles, including all known lizards, snakes, geckos and skinks. Many of the world's smallest reptiles are classified as scaly. Venom is a common feature of at least some species in this order as a means of defense against prey. Because venom evolved from different pre-existing proteins found throughout the body, the form and function of venom is very diverse.

Crocodiles —an ancient order that includes all modern alligators, crocodiles, caimans, and gharials—are among the largest carnivorous carnivores on Earth. With flat snouts, tough skin, long tails and rows of large teeth, crocodiles spend most of their lives in or near water. This order is the closest living relative to birds. That's because the ancestors of crocodiles were closely related to dinosaurs.

Rhynchocephalia – This order dates back to the Triassic period about 200 to 250 million years ago. Once incredibly diverse, it has been reduced to just one living genus, the New Zealand lizard-like lizard, which includes just two species. Despite their lizard-like appearance (they are a sister group of scaly animals), this order actually shares some basic morphological traits with crocodiles and dinosaurs.

Evolutionary History of Reptiles

About 400 million years ago, when four-legged vertebrates emerged on land, semi-aquatic amphibians evolved most. This semi-aquatic lifestyle is reflected in its morphology and behaviour. But several advances in lungs, bone structure and egg composition allowed the earliest reptiles to leave the water and thrive in otherwise unexplored ecological niches around the world.

Some 310 to 320 million years ago, the first clear signs of reptiles appeared in the fossil record. At that time, most of their territory was covered in swamps. Characterized by the lack of a hole in the back of the skull, anaporas were among the first reptiles to evolve. Diapsids have two holes near the back of their skulls, including modern reptiles, and indeed nearly all reptiles from the past 250 million years. Currently only the tortoise is classified in the anaporid group (and even then, it can't really be considered a "true" anapora, since the solid posterior skull probably evolved later).

Over millions of years, reptiles have continued to undergo many evolutions and changes. Archosaurs, including dinosaurs, crocodiles, and birds, first appeared in the fossil record during the Late Triassic period, about 200 million years ago. They flourished and became especially prominent during the Jurassic period. Primitive turtles first emerged around the same time and have remained the same size ever since. Squamates likely evolved during the Middle Jurassic, about 16 to 170 million years ago, but true snakes did not evolve until about 100 million years ago.

Part of this evolution was due to huge, sudden changes in ecosystems, including a mass extinction event 250 million years ago that killed roughly 90% of all species on Earth, and of course, asteroid impacts and volcanic activity that killed all non-avian dinosaurs Extinct about 65 million years ago. Since then, reptiles have evolved to be smaller and to share ecosystems with birds and mammals (which actually split off from early reptiles about 300 million years ago).

types of reptiles

lizard lizard

Lizards form small social groups containing dominant and subordinate males.

chameleon

There are nearly 400 types, several of which change color.

arabian cobra

The Arabian Cobra is the only true cobra species that can be found in the Arabian Peninsula.

armadillo lizard

They communicate by sticking out their tongues, wagging their heads, and wagging their tails.

aspartic acid

It was a symbol of royalty in Egypt, and its bite was used to execute criminals in Greco-Roman times.

giant crocodile

Largest terrestrial carnivore of the Cenozoic

beauty rat snake

If left undisturbed, beauty rat snakes are relatively harmless and only attempt to bite out of fear.

black Mamba

The black mamba is the longest venomous snake in Africa and the second longest in the world.

black rat snake

They are also known as black pilot snakes because of a myth that they "pilot" venomous snakes to a lair where they can go scarred in the winter.

Black Throat Monitor

The black-throated monitor lizard is the second longest and largest lizard species in Africa.

Black-headed python

Black-headed pythons use their heads to collect heat while their bodies remain concealed and secure.

blind snake

Blind snakes are often mistaken for worms.

blood python

Blood pythons are named for the blood-red markings on their skin.

bolivian python

This is a newly described species! In 2002, scientists realized they had found a different species in Bolivia.

catchphrase

Boomslangs are primarily arboreal, but sometimes come to the ground as well.

box turtle

This reptile has an S-shaped neck that pulls the entire head into the shell.

Brooksia

If threatened, the Brookesia micra will curl up and pretend to be a dead leaf.

brown water snake

Has more scales than any other water snake on the continent: 27 to 33 rows of dorsal scales!

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bull snake

Considered a "farmer's friend" because it eats mice and other pests.

jungle viper

Bush vipers are predators that bite their prey with their fangs hanging from a branch

caiman

Can grow up to 6 meters long!

carpet viper

Carpet vipers probably bite and kill more people than any other snake species.

Cascabell

Cascabels rely on their camouflage first, and if that doesn't work, rattle.

cat snake

Some cat snakes have a graspable tail that helps them climb trees.

alligator

Unlike other crocodiles, the alligator is fully armored, even on its belly.

cobra

Several drugs have been manufactured using cobra venom.

colette's snake

Collett's snakes are beautiful, but almost as dangerous as mulga snakes.

Copperhead

Unsurprisingly, copperheads get their name from their bronze-colored heads.

coral snake

There are more than 80 species of coral snakes in the world.

corn snake

Partially arboreal, corn snakes are excellent climbers.

cotton mouth

The cottonmouth snake (also known as the water buckskin) is a highly venomous viper that spends most of its time near water.

crested gecko

Crested geckos can walk on glass and even have a tail they can grab.

Crocodile

Not much has changed in 200 million years!

Crocodiles

Crocodilians include extinct ancient species as well as 26 extant species today.

cuban python

One of the only snakes observed to use a cooperative hunting strategy.

death viper

The death viper is more closely related to the cobra than to other Australian snake species.

desert king snake

Desert king snakes will roll over and play dead when they feel threatened.

Dumerier's python

Some tribes believed that snake skin contained the spirits of their ancestors.

Pygmy python

Some species can change color from dark to light and back again.

earless monitor lizard

These lizards can actually shut down their metabolism and remain unconscious for long periods of time.

Oriental Glass Lizard

When a glass lizard loses its tail, it can grow another. But the new tail doesn't have the markings of the old tail, and it's usually shorter.

Oriental blue snake

Eastern indigo snakes frequently hunt and eat rattlesnakes and may be immune to rattlesnake venom.

Eastern rat snake

Rat snakes are medium to large nonvenomous snakes that kill by constriction.

eyelash viper

While eyelash vipers can be kept as pets, be careful – they are venomous!

false coral snake

False coral snake mimics coral snakes and cobras to scare away predators

flying snake

Flying snakes are the only limbless vertebrates or animals with a backbone that can glide!

fox snake

In some areas, fox snakes and gopher snakes interbreed in the wild.

garter snake

Female garter snakes give birth to live young instead of laying eggs!

gecko

There are thought to be more than 2,000 species!

Crocodile

Males can blow bubbles with the bump on their nose!

Monster lizard

This lizard's tail doubles as a fat storage facility!

green chameleon

It communicates with head movement, color and flab

Green Mamba

The Green Mamba is fast, reaching speeds of up to 7 mph.

green tree python

Green tree pythons are non-venomous, so they have some very unique and very successful hunting techniques in order to subdue their prey.

ground snake

It is sometimes called a miter snake because the markings on its head look like a bishop's miter

Hellbringer

This giant salamander has lived in its ecosystem for about 65 million years

angle adder

Males tend to be more brightly colored than females, which are much larger than males.

horned lizard

Horned lizards can spurt blood from their eyes.

horned viper

Horned viper crosswinds across the desert at their home.

Ichthyosaur

Give birth to living young instead of laying eggs like other reptiles

Iguana

Communicate using visual signals!

blue snake

Indigo snakes use brute force to overwhelm their prey.

jamaican python

When a Jamaican python is coiled, it almost looks like two snakes together because of the color pattern.

kilback

The checkered keelfish of the East Indies can detach and regrow its tail, like a lizard.

Cobra

They are the longest venomous snakes in the world.

Krait

A painless bite can result in death.

lazarus lizard

Lazarus lizards can communicate through chemical and visual signals.

leopard gecko

The first domesticated lizard ever! Due to selective breeding, there are now over 100 unique color morphs.

lizard

There are about 5,000 different species!

mamba

The black mamba is terrestrial, while the other three species are arboreal.

mangrove snake

Mangrove snakes have small fangs that are more like enlarged teeth at the back of the jaw.

marine iguana

Adult marine iguanas vary in size depending on the size of the island they live on.

North American gnome

The name "Massasauga" comes from the Chippewa language and means "big estuary".

monitor lizard

Some believe monitor lizards still exist in remote areas, although these beliefs have never been substantiated by evidence.

Mojave ball python

Unlike the typical banded or "alien head" pattern of most ball python morphs, the Mojave morph's pattern features many large circular spots with small dark brown dots in the center.

nile crocodile

Unlike other reptiles, male Nile crocodiles join females in guarding their ovaries.

olive sea snake

Olive sea snakes can stay underwater for up to two hours without breathing.

ornate box turtle

One of the greatest threats to orate box turtle populations is that during extremely hot or cold breeding seasons, the vast majority of hatchlings are of the same sex.

Philippine Cobra

The Philippine cobra is a highly venomous cobra.

pipe snake

Some of these snakes flatten their necks and raise their heads when threatened, mimicking a cobra.

puff adder

The large snake is so named because when it is directly threatened by a predator or a human, it inflates its body to appear larger than it is.

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Pygmy Python

These snakes have been seen traveling in groups of 3-5.

queen snake

The queen snake has armor-like scales on top of its head

racing snake

Race snakes can reach speeds of 3.5 miles per hour

rainbow python

Rainbow pythons are so named because their iridescent skin refracts light and creates an iridescent effect.

rat snake

Rat snakes are pythons in the python family.

rattlesnake

Rattlesnakes may have evolved rattlesnakes to warn bison to stay away from them.

Red Ear Slider

Sliders spend a lot of time basking in the sun. As cold-blooded animals, they need sunlight for warmth.

ribbon snake

Banded snakes love water but are also excellent climbers.

rock python

The rock python may have hybridized with an escaped Burmese python in Florida.

rose python

One of the few naturally occurring iridescent snakes!

rubber python

The rubber python is one of the only python species left in North America.

sand viper

Sand vipers are a nuisance snake in some areas.

Savannah Monitor

The savannah monitor lizard is one of the most popular captive lizards.

ball python

The body of a scaleless ball python is completely smooth except for each eye, which is covered with eye scales.

sea snake

Sea snakes are extremely poisonous, more powerful than cobras! "

sea turtle

Always return to the same beach to spawn!

skink lizard

Some skinks lay eggs in certain habitats while laying baby skinks in other habitats.

slow worm

Found everywhere in English gardens!

Saber-toothed crocodile

The largest species of the Smilosuchus genus, S. gregorii, was the largest known reptile at the time, reaching a length of 39 feet.

snake

There are approximately 4,000 known species worldwide

cobra

The nosed cobra, also known as the barbed cobra, is one of the most venomous snake species in all of Africa.

southern black racer

These snakes live underground, under piles of fallen leaves or in bushes, and they are excellent swimmers.

Southern hognose snake

The southern hognose snake has an upturned snout, which allows it to dig into soil.

spit cobra

A spitting cobra is a cobra that spits venom at both its predator and its prey.

spotted python

Their favorite food is bats, which they hang over the entrance of their caves to snatch them from mid-air!

stiletto snake

Due to its unique venom delivery system, the stiletto snake is nearly impossible to hold safely in the usual way (fingers behind the head) without being bitten.

Psycho

Largest known freshwater turtle ever!

Sulcata tortoise

Some cultures in Africa believe that the sulcata tortoise is an intermediary between humans and their ancestors and gods.

Taipan

most venomous snake on earth

Texas Indigo Snake

Texas indigo snakes are known for chasing, subduing, and eating rattlesnakes.

Texas Night Snake

The Texas night snake has vertical pupils that help it see better at night.

Texas rat snake

The Texas ratsnake is one of the most common subspecies of the western ratsnake in the wild.

tiger snake

Tiger Snakes can stay underwater for nine minutes without returning to the surface to breathe

Titanoboa

Titanoboa was a giant 42-foot python that lived 58-60 million years ago.

turtle

Can live to more than 150 years old!

tree snake

While this snake's venomous bite is harmless to adults, it can be dangerous for children

sea turtle

Certain species of aquatic turtles can get up to 70% of their oxygen through their butts.

branch snake

The twig snake is one of the few posterior-toothed snakes whose bite is highly venomous and potentially fatal.

Ulutu snake

Female Ulutu snakes grow longer and heavier than their male counterparts

vine snake

The slender body and elongated snout give the vine snake a regal look.

poisonous snake

The venomous snake is one of the most widespread snake species with the most habitats

western hognose snake

These snakes are mainly solitary and they only communicate with each other during the breeding season.

Western rat snake

Western rat snakes have special scales on their abdomens that help them climb trees.

python

Woma pythons often prey on venomous snakes and are immune to certain venoms.

wooden turtle

Temperature determines the sex of turtle eggs

worm snake

If picked up, they emit a foul-smelling liquid!

Yalala

females are much larger than males

yellow python

Compared to other snakes, pythons hunt prey that is much larger than their body weight.

yellow cobra

Yellow cobras belong to one of the most dangerous families in the world.

list of reptiles

Different types of reptiles definition photos and more 1

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Reptiles: Different Types, Definitions, Photos and More FAQs (Frequently Asked Questions)

What are reptiles?

Reptiles are a group of cold-blooded animals characterized by rough skin and egg laying. It's just one of three vertebrates, along with mammals and birds, that have an amniotic membrane, or internal sac, at the embryonic stage of development.

What are the characteristics of reptiles?

The reptile's skin is covered with rough scales, or bony plates, which shed periodically. These cold-blooded organisms are unable to maintain a constant body temperature and are completely dependent on the external environment to heat up or cool down.

What are the types of reptiles?

The three main orders of reptiles are turtles, lizards and snakes, crocodiles and all their varieties. A fourth order, the Rhynchocephalia, consists of only two extant species but many extinct ones.

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