A poison is inhaled or ingested, whereas venom produced by snakes is injected into its victim via fangs. The albumin 9 further protects the embryo and serves as a reservoir for water and protein. Pick plants whose size fits the animal and terrarium size; for example, ferns are great for tree frogs while pray plants are good for moderate sized lizards. Flies Flies can be purchased as larva. Their kidneys extract nitrogenous wastes from the bloodstream, but instead of excreting it as urea dissolved in urine as we do, they excrete it in the form of uric acid.
Crocodilians actually have a muscular diaphragm that is analogous to the mammalian diaphragm. The difference is that the muscles for the crocodilian diaphragm pull the pubis part of the pelvis, which is movable in crocodilians back, which brings the liver down, thus freeing space for the lungs to expand. This type of diaphragmatic setup has been referred to as the " hepatic piston ".
The airways form a number of double tubular chambers within each lung. On inhalation and exhalation air moves through the airways in the same direction, thus creating a unidirectional airflow through the lungs.
A similar system is found in birds,  monitor lizards  and iguanas. Most reptiles lack a secondary palate , meaning that they must hold their breath while swallowing. Crocodilians have evolved a bony secondary palate that allows them to continue breathing while remaining submerged and protect their brains against damage by struggling prey.
Skinks family Scincidae also have evolved a bony secondary palate, to varying degrees. Snakes took a different approach and extended their trachea instead. Their tracheal extension sticks out like a fleshy straw, and allows these animals to swallow large prey without suffering from asphyxiation.
How turtles and tortoises breathe has been the subject of much study. To date, only a few species have been studied thoroughly enough to get an idea of how those turtles breathe. The varied results indicate that turtles and tortoises have found a variety of solutions to this problem. The difficulty is that most turtle shells are rigid and do not allow for the type of expansion and contraction that other amniotes use to ventilate their lungs.
Some turtles, such as the Indian flapshell Lissemys punctata , have a sheet of muscle that envelops the lungs. When it contracts, the turtle can exhale. When at rest, the turtle can retract the limbs into the body cavity and force air out of the lungs.
When the turtle protracts its limbs, the pressure inside the lungs is reduced, and the turtle can suck air in. Turtle lungs are attached to the inside of the top of the shell carapace , with the bottom of the lungs attached via connective tissue to the rest of the viscera. By using a series of special muscles roughly equivalent to a diaphragm , turtles are capable of pushing their viscera up and down, resulting in effective respiration, since many of these muscles have attachment points in conjunction with their forelimbs indeed, many of the muscles expand into the limb pockets during contraction.
Breathing during locomotion has been studied in three species, and they show different patterns. Adult female green sea turtles do not breathe as they crutch along their nesting beaches. They hold their breath during terrestrial locomotion and breathe in bouts as they rest. North American box turtles breathe continuously during locomotion, and the ventilation cycle is not coordinated with the limb movements. The last species to have been studied is the red-eared slider, which also breathes during locomotion, but takes smaller breaths during locomotion than during small pauses between locomotor bouts, indicating that there may be mechanical interference between the limb movements and the breathing apparatus.
Box turtles have also been observed to breathe while completely sealed up inside their shells. Reptilian skin is covered in a horny epidermis , making it watertight and enabling reptiles to live on dry land, in contrast to amphibians.
Compared to mammalian skin, that of reptiles is rather thin and lacks the thick dermal layer that produces leather in mammals. In lepidosaurians , such as lizards and snakes, the whole skin is covered in overlapping epidermal scales. Such scales were once thought to be typical of the class Reptilia as a whole, but are now known to occur only in lepidosaurians.
Lacking a thick dermis, reptilian leather is not as strong as mammalian leather. It is used in leather-wares for decorative purposes for shoes, belts and handbags, particularly crocodile skin.
Reptiles shed their skin through a process called ecdysis which occurs continuously throughout their lifetime. In particular, younger reptiles tend to shed once every 5—6 weeks while adults shed times a year. Once full size, the frequency of shedding drastically decreases. The process of ecdysis involves forming a new layer of skin under the old one. Proteolytic enzymes and lymphatic fluid is secreted between the old and new layers of skin. Consequently, this lifts the old skin from the new one allowing shedding to occur.
Traumatic injuries on the other hand, form scars that will not allow new scales to form and disrupt the process of ecdysis. Excretion is performed mainly by two small kidneys. In diapsids, uric acid is the main nitrogenous waste product; turtles, like mammals , excrete mainly urea.
Unlike the kidneys of mammals and birds, reptile kidneys are unable to produce liquid urine more concentrated than their body fluid. This is because they lack a specialized structure called a loop of Henle , which is present in the nephrons of birds and mammals. Because of this, many reptiles use the colon to aid in the reabsorption of water. Some are also able to take up water stored in the bladder. Excess salts are also excreted by nasal and lingual salt glands in some reptiles.
In all reptiles the urinogenital ducts and the anus both empty into an organ called a cloaca. In some reptiles, a midventral wall in the cloaca may open into a urinary bladder, but not all. It is present in all turtles and tortoises as well as most lizards, but is lacking in the monitor lizard , the legless lizards.
It is absent in the snakes, alligators, and crocodiles. Many turtles, tortoises, and lizards have proportionally very large bladders. Turtles have two or more accessory urinary bladders, located lateral to the neck of the urinary bladder and dorsal to the pubis, occupying a significant portion of their body cavity.
The right section is located under the liver, which prevents large stones from remaining in that side while the left section is more likely to have calculi.
Most reptiles are insectivorous or carnivorous and have simple and comparatively short digestive tracts due to meat being fairly simple to break down and digest. Digestion is slower than in mammals , reflecting their lower resting metabolism and their inability to divide and masticate their food. While modern reptiles are predominantly carnivorous, during the early history of reptiles several groups produced some herbivorous megafauna: Herbivorous reptiles face the same problems of mastication as herbivorous mammals but, lacking the complex teeth of mammals, many species swallow rocks and pebbles so called gastroliths to aid in digestion: The rocks are washed around in the stomach, helping to grind up plant matter.
The reptilian nervous system contains the same basic part of the amphibian brain, but the reptile cerebrum and cerebellum are slightly larger.
Most typical sense organs are well developed with certain exceptions, most notably the snake 's lack of external ears middle and inner ears are present. There are twelve pairs of cranial nerves. Reptiles are generally considered less intelligent than mammals and birds. Larger lizards, like the monitors , are known to exhibit complex behavior, including cooperation. The Komodo dragon is even known to engage in play,  as are turtles, which are also considered to be social creatures, [ citation needed ] and sometimes switch between monogamy and promiscuity in their sexual behavior.
Most reptiles are diurnal animals. The vision is typically adapted to daylight conditions, with color vision and more advanced visual depth perception than in amphibians and most mammals. In some species, such as blind snakes , vision is reduced.
Some snakes have extra sets of visual organs in the loosest sense of the word in the form of pits sensitive to infrared radiation heat. Such heat-sensitive pits are particularly well developed in the pit vipers , but are also found in boas and pythons. These pits allow the snakes to sense the body heat of birds and mammals, enabling pit vipers to hunt rodents in the dark.
Reptiles generally reproduce sexually , though some are capable of asexual reproduction. Most reptiles have copulatory organs , which are usually retracted or inverted and stored inside the body. In turtles and crocodilians, the male has a single median penis , while squamates, including snakes and lizards, possess a pair of hemipenes , only one of which is typically used in each session. Tuatara, however, lack copulatory organs, and so the male and female simply press their cloacas together as the male discharges sperm.
Most reptiles lay amniotic eggs covered with leathery or calcareous shells. An amnion , chorion , and allantois are present during embryonic life. The eggshell 1 protects the crocodile embryo 11 and keeps it from drying out, but it is flexible to allow gas exchange.
The chorion 6 aids in gas exchange between the inside and outside of the egg. It allows carbon dioxide to exit the egg and oxygen gas to enter the egg.
The albumin 9 further protects the embryo and serves as a reservoir for water and protein. The allantois 8 is a sac that collects the metabolic waste produced by the embryo. The amniotic sac 10 contains amniotic fluid 12 which protects and cushions the embryo. The amnion 5 aids in osmoregulation and serves as a saltwater reservoir. The yolk sac 2 surrounding the yolk 3 contains protein and fat rich nutrients that are absorbed by the embryo via vessels 4 that allow the embryo to grow and metabolize.
The air space 7 provides the embryo with oxygen while it is hatching. This ensures that the embryo will not suffocate while it is hatching. There are no larval stages of development. Viviparity and ovoviviparity have evolved in many extinct clades of reptiles and in squamates. In the latter group, many species, including all boas and most vipers, utilize this mode of reproduction. The degree of viviparity varies; some species simply retain the eggs until just before hatching, others provide maternal nourishment to supplement the yolk, and yet others lack any yolk and provide all nutrients via a structure similar to the mammalian placenta.
The earliest documented case of viviparity in reptiles is the Early Permian mesosaurs ,  although some individuals or taxa in that clade may also have been oviparous because a putative isolated egg has also been found. Several groups of Mesozoic marine reptiles also exhibited viviparity, such as mosasaurs , ichthyosaurs , and Sauropterygia , a group that include pachypleurosaurs and Plesiosauria. Asexual reproduction has been identified in squamates in six families of lizards and one snake.
In some species of squamates, a population of females is able to produce a unisexual diploid clone of the mother. This form of asexual reproduction, called parthenogenesis , occurs in several species of gecko , and is particularly widespread in the teiids especially Aspidocelis and lacertids Lacerta. In captivity, Komodo dragons Varanidae have reproduced by parthenogenesis.
Parthenogenetic species are suspected to occur among chameleons , agamids , xantusiids , and typhlopids. Some reptiles exhibit temperature-dependent sex determination TDSD , in which the incubation temperature determines whether a particular egg hatches as male or female. TDSD is most common in turtles and crocodiles, but also occurs in lizards and tuatara. Many small reptiles, such as snakes and lizards that live on the ground or in the water, are vulnerable to being preyed on by all kinds of carnivorous animals.
Thus avoidance is the most common form of defense in reptiles. Reptiles tend to avoid confrontation through camouflage. Two major groups of reptile predators are birds and other reptiles, both of which have well developed color vision.
Thus the skins of many reptiles have cryptic coloration of plain or mottled gray, green, and brown to allow them to blend into the background of their natural environment.
When camouflage fails to protect them, blue-tongued skinks will try to ward off attackers by displaying their blue tongues, and the frill-necked lizard will display its brightly colored frill. These same displays are used in territorial disputes and during courtship. Rattlesnakes rapidly vibrate the tip of the tail, which is composed of a series of nested, hollow beads to ward of approaching danger. In contrast to the normal drab coloration of most reptiles, the lizards of the genus Heloderma the Gila monster and the beaded lizard and many of the coral snakes have high-contrast warning coloration, warning potential predators they are venomous.
Camouflage does not always fool a predator. When caught out, snake species adopt different defensive tactics and use a complicated set of behaviors when attacked. Some first elevate their head and spread out the skin of their neck in an effort to look large and threatening.
Failure of this strategy may lead to other measures practiced particularly by cobras, vipers, and closely related species, which use venom to attack.
The venom is modified saliva, delivered through fangs from a venom gland. When a crocodilian is concerned about its safety, it will gape to expose the teeth and yellow tongue. If this doesn't work, the crocodilian gets a little more agitated and typically begins to make hissing sounds. After this, the crocodilian will start to change its posture dramatically to make itself look more intimidating.
The body is inflated to increase apparent size. If absolutely necessary it may decide to attack an enemy. Some species try to bite immediately. Some will use their heads as sledgehammers and literally smash an opponent, some will rush or swim toward the threat from a distance, even chasing the opponent onto land or galloping after it.
Many species also possess canine -like teeth. These are used primarily for seizing prey, but are also used in fighting and display. Geckos , skinks , and other lizards that are captured by the tail will shed part of the tail structure through a process called autotomy and thus be able to flee.
The detached tail will continue to wiggle, creating a deceptive sense of continued struggle and distracting the predator's attention from the fleeing prey animal. The detached tails of leopard geckos can wiggle for up to 20 minutes. In the shingleback skink and some species of geckos, the tail is short and broad and resembles the head, so that the predators may attack it rather than the more vulnerable front part.
Reptiles that are capable of shedding their tails can partially regenerate them over a period of weeks. The new section will however contain cartilage rather than bone, and will never grow to the same length as the original tail.
It is often also distinctly discolored compared to the rest of the body and may lack some of the external sculpting features seen in the original tail. Dinosaurs have been widely depicted in culture since the English palaeontologist Richard Owen coined the name dinosaur in As soon as , the Crystal Palace Dinosaurs were on display to the public in south London.
The depictions range from the realistic, as in the television documentaries of the s and first decade of the 21st century, or the fantastic, as in the monster movies of the s and s. The snake or serpent has played a powerful symbolic role in different cultures. In Egyptian history , the Nile cobra adorned the crown of the pharaoh. Once you have assured that the reptile is healthy and in a properly established environment, certain tricks may be employed if the reptile is still not self-feeding: Changes in Temperatures and Humidity The humidity and temperatures in an enclosure will vary through the year as the ambient room air temperatures and humidity rise and fall.
You may need to boost the humidity artificially more during the winter and winter months than during the Fall, for example. Hygrometers can be used to measure humidity and may be used as a guide to alert you when you need to boost the humidity or back off. Unfortunately, more is known about the temperature requirements of species kept in captivity than is known about their humidity needs.
In the absence of specific humidity data, you will have to learn how to judge the adequacy of humidity based on the above points. During the the winter, the fall in outside temperatures results in a lowering of the temperatures inside our homes. This drop in ambient room air temperature often results in a lowering of the temperatures inside the reptile enclosures.
Always monitor the temperatures with several thermometers placed inside the enclosure. You may find that during the colder months you many not only have to boost humidity inside the room or enclosure, but you may have to add stronger or additional heating equipment just to be able to maintain the proper temperatures. One final factor that must be mentioned is the human tendency to demand that animals share the human's time schedule. Many people work during the day, coming home tired at night, often with an hour or more of chores to be done before they can settle down to relax.
At that time, they may want to feed their reptile, or take it out for some together time. The problem is that if their reptile is a diurnal active during the day species, it needs to sleep at night. Constant disruption of the sleep cycle, as well as being forced to eat at night rather than during the day, results in long term low levels of stress. The same is true for people who work or otherwise stay up all night and sleep throughout most of the day.
While this life style may be okay for nocturnal reptiles other than the fact that nocturnal species do still require darkness at night to function normally , it is stressful for the diurnal and even for many crepuscular species. When we keep animals, we must accommodate their needs; they should not be forced to accommodate our schedules.
So, what does all of this have to do with my reptile's health? Stresses, little and big, as well as the direct effects of environmental problems cage size, orientation, heating, lighting, feeding, humidity, etc. Stress itself can suppress immune function, making the body unable to naturally fight off infection or keep internal parasites under control.
The more stress, or the longer that it is allowed to continue, the weaker the animal becomes and the less tolerant it is to continued stresses and other problems in its environment.
Reptiles take a long time to die. Because of their ectothermy, their cold-bloodedness, they are able to conserve energy to maintain basic body functions for a long time, long after a mammal or bird would have succumbed or have deteriorated to the point where the owner would notice. Reptiles do not die "suddenly. Those animals most adept at suppressing signs of ill-health or injury are those that will have a chance to recover before being eaten.
In the wild as in captivity, reduced activity and increased hiding are behaviors associated with attempts at conserving energy the less one moves, the fewer calories burned, a common reaction to slow starvation and to giving the body more calories to put into healing, for example and trying to hide to avoid predation when the animal is too weak or too cold to effectively defend itself.
Behavioral Changes Changes in behavior can be a sign of an underlying physical problem. We tend to think of health problems as causing lethargy and loss of appetite, but animals may also become snappy, cranky, and may react abnormally to accustomed interaction and stimuli. Some iguanas may get aggressive. When the aggression occurs in green iguanas, known for their breeding season and territorial aggression, such behavioral changes are often dismissed as "just" being related to "typical" male aggression.
As an increasing number of iguana keepers are finding, abnormal aggression may also caused by huge bladder stones, tumors, abscessed organs, and other as yet undefined, pain, disorders and pathologies.
When investigating the possible causes of abnormally aggressive behavior, do not discount a primary physiological cause until you and your vet have thoroughly checked it out. Behavioral assessment of welfare. Scientists Center for Animal Welfare. The science of animal well-being. Animal Welfare Information Center Newsletter, 4 1 , The psychological well-being of reptiles. Humane Innovations and Alternatives , Evaluating pain and stress in reptiles. The use of behavioral management techniques to reduce or eliminate abnormal behavior.
Animal Welfare Information Center Newsletter, 4 , , Saunders Company, Philadelphia, PA. Biological response to stress: Key to assessment of animal well-being?
Society for the Study of Reptiles and Amphibians. Captive management and conservation of amphibians and reptiles.
Murphy, Kraig Adler, Joseph T. Reptilian ethology in captivity: Observations of some problems and an evaluation of their aetiology. Appl Anim Behav Sci, 26 , Important ethological and other considerations of the study and maintenance of reptiles in captivity.
Applied Animal Behaviour Science, 27 4 , Observations on disease-associated preferred body temperatures in reptiles.
Applied animal behavior science, 28 4 , Health and welfare of captive reptiles. An introductory biology of amphibians and reptiles. Academic Press, New York. Fluid and Fluid Therapy for Reptiles. Guidelines for Medicating Sick Herps.
Iguana Breeding Season Basics. Signs of Ingestion of Toxic Substances. Heading off problems before they start. Reptiles offer economic, aesthetic, symbolic, and ecological values to humans. They are integral to food chains and in the reduction of agricultural pests, are part of the diet in some cultures, are used in producing leather goods, and are kept as pets. Some reptiles are considered aesthetically pleasing with their vivid colors. In religion , reptiles have served an important symbolic purpose, particularly noteworthy in the appearance of the serpent in Genesis.
See Reptiles and humans. A herpetologist is a zoologist who studies reptiles and amphibians. According to a report by Uetz in , comprehensive compilations reveal a total of 7, species of reptiles, with the majority being lizards 4, species and snakes 2, , and with 23 described species of living crocodiles, species of turtles, amphisbaenias , and 2 species of tuataras.
Uetz reported that 51 percent of known reptile species belong to one of three families: New reptile species continue to be described at the rate of about 60 species per year Uetz A subsequent tabulation by Uetz in showed a total of 8, extant reptile species, and his March list revealed 8, known species. Uetz reported 2, living species of reptiles in Asia including New Guinea , 1, in South America , 1, in Africa , 1, in Central America , and in Australia. There were but species of living reptiles in Europe and in North America.
Most reptiles have closed circulation via a three-chamber heart comprising two atria and one variably-partitioned ventricle. There is usually one pair of aortic arches. In spite of this, due to the fluid dynamics of blood flow through the heart, there is little mixing of oxygenated and deoxygenated blood in the three-chamber heart.
Furthermore, the blood flow can be altered to shunt either deoxygenated blood to the body or oxygenated blood to the lungs, which gives the animal greater control over its blood flow, allowing more effective thermoregulation and longer diving times for aquatic species.
There are some interesting exceptions among reptiles. For instance, crocodilians have an incredibly complicated four-chamber heart that is capable of becoming a functionally three-chamber heart during dives Mazzotti Also, it has been discovered that some snake and lizard species for example, monitor lizards and pythons have three-chamber hearts that become functional four-chamber hearts during contraction.
This is made possible by a muscular ridge that subdivides the ventricle during ventricular diastole and completely divides it during ventricular systole. Because of this ridge, some of these squamates are capable of producing ventricular pressure differentials that are equivalent to those seen in mammalian and avian hearts Wang et al. All reptiles breathe using lungs. Aquatic turtles have developed more permeable skin, and for some species even gills in their anal region Orenstein Even with these adaptations, breathing is never fully accomplished without lungs.
Lung ventilation is accomplished differently in each main reptile group. In squamates , the lungs are ventilated almost exclusively by the axial musculature, which is also the same musculature used during locomotion.
Because of this constraint, most squamates are forced to hold their breath during intense runs. Some, however, have a way around it.
Varanids and a few other lizard species employ buccal pumping a method of respiration using the throat muscles as a complement to their normal breathing. This allows the animals to completely fill their lungs during intense locomotion, and thus remain aerobically active for a long time. Tegu lizards are known to possess a proto-diaphragm, which separates the pulmonary cavity from the visceral cavity. While not actually capable of movement, it does allow for greater lung inflation, by taking the weight of the viscera off the lungs Klein et al.
Crocodilians have a muscular diaphragm that is analogous to the mammalian diaphragm. The difference is that the muscles for the crocodilian diaphragm pull the pubis part of the pelvis, which is movable in crocodilians back, which brings the liver down, thus freeing space for the lungs to expand. This type of diaphragmatic setup has been referred to as the "hepatic piston.
Turtles and tortoises have found a variety of solutions to breathing, given that most turtle shells are rigid and do not allow for the type of expansion and contraction that other amniotes use to ventilate their lungs.
Some turtles such as the Indian flapshell Lissemys punctata have a sheet of muscle that envelopes the lungs. When it contracts, the turtle can exhale. When at rest, the turtle can retract the limbs into the body cavity and force air out of the lungs. When the turtle protracts its limbs, the pressure inside the lungs is reduced, and the turtle can suck air in.
Turtle lungs are attached to the inside of the top of the shell carapace , with the bottom of the lungs attached via connective tissue to the rest of the viscera. By using a series of special muscles roughly equivalent to a diaphragm , turtles are capable of pushing their viscera up and down, resulting in effective respiration, since many of these muscles have attachment points in conjunction with their forelimbs indeed, many of the muscles expand into the limb pockets during contraction.
Breathing during locomotion has been studied in three species, and they show different patterns. Adult female green sea turtles do not breathe as they crutch along their nesting beaches. They hold their breath during terrestrial locomotion and breathe in bouts as they rest. North American box turtles breathe continuously during locomotion, and the ventilation cycle is not coordinated with the limb movements Landberg et al. They are probably using their abdominal muscles to breathe during locomotion.
The red-eared sliders also breathe during locomotion, but they had smaller breaths during locomotion than during small pauses between locomotion bouts, indicating that there may be mechanical interference between the limb movements and the breathing apparatus.
Box turtles have also been observed to breathe while completely sealed up inside their shells Landberg et al. Most reptiles lack a secondary palate, meaning that they must hold their breath while swallowing. Crocodilians have evolved a bony secondary palate that allows them to continue breathing while remaining submerged and protect their brains from getting kicked in by struggling prey.
Skinks family Scincidae also have evolved a bony secondary palate to varying degrees. Snakes have a different approach and extend their trachea instead.
Their tracheal extension sticks out like a fleshy straw. By thrusting their windpipe into the throat, these animals can swallow large prey without suffering from asphyxiation, despite the fact that swallowing may take several hours. Land-dwelling reptiles, such as snakes and lizards, excrete nitrogenous wastes in pasty or dry form as crystals of uric acid Towle Two small kidneys are used in excretion.
Snakes have hinged upper and lower jaws, which move independently.