Do frogs breathe through their skin?
Cutaneous respiration
The skin of amphibians is a major site of respiration in all species for which measurements are available. Cutaneous respiration is the sole respiratory mode of lungless salamanders (family Plethodontidae) which lack lungs entirely yet constitute the largest family of salamanders. Cutaneous respiration in frogs and other amphibians may be the primary respiratory mode during colder temperatures.
Frog
The call or croak of a frog is unique to its species. Frogs create this sound by passing air through the larynx in the throat. In most calling frogs, the sound is amplified by one or more vocal sacs, membranes of skin under the throat or on the corner of the mouth, that distend during the amplification of the call. Some frog calls are so loud that they can be heard up to a mile away. Additionally, some species have been found to use man-made structures such as drain pipes for artificial amplification of their call.
Amphibious caterpillar
These caterpillars don’t have gills or anything that covers the trachea to operate marine mammals' surface-to-breathe technique for respiration. Instead they appear to absorb oxygen directly through pores in their "skin" from the enveloping water. The caterpillars require flowing water to provide sufficient oxygen. They spin "silk" tethers to attach themselves to the downstream sides of rocks to keep from washing away.
Goliath frog
A lateral fold extends from the eye to the posterior portion of the tympanum. Toes are fully webbed, with large interdigital membranes extending down to the toe tips. The second toe is the longest. The skin on the dorsum and on top of the limbs is granular. Dorsal coloration is green sienna, while the abdomen and ventral part of the limbs are yellow/orange. They have acute hearing, but no vocal sac, and also lack nuptial pads.
Royal ghost frog
Ghost frogs get their name as one of the six species found in Skeleton Gorge (on Table Mountain), South Africa. The underside of the body, including the jaw, has small hooks, which help the frogs climb over wet rocks near their habitats. The frogs measure in length. It is in the same size range as Hewitt's ghost frog, but is smaller than Purcell's ghost frog. The top side of its body is brown with yellow spots, and the underside is white. The limbs are plain-colored, and flesh-colored underneath. Their tadpoles take up to two years to develop fully. The call of the royal ghost frog is a harsh, creaking sound, given at around one call per second.
Amphibian
Frog larvae are known as tadpoles and typically have oval bodies and long, vertically flattened tails with fins. The free-living larvae are normally fully aquatic, but the tadpoles of some species (such as "Nannophrys ceylonensis") are semi-terrestrial and live among wet rocks. Tadpoles have cartilaginous skeletons, gills for respiration (external gills at first, internal gills later), lateral line systems and large tails that they use for swimming. Newly hatched tadpoles soon develop gill pouches that cover the gills. The lungs develop early and are used as accessory breathing organs, the tadpoles rising to the water surface to gulp air. Some species complete their development inside the egg and hatch directly into small frogs. These larvae do not have gills but instead have specialised areas of skin through which respiration takes place. While tadpoles do not have true teeth, in most species, the jaws have long, parallel rows of small keratinized structures called keradonts surrounded by a horny beak. Front legs are formed under the gill sac and hind legs become visible a few days later.
Frog
Some frogs protect their offspring inside their own bodies. Both male and female pouched frogs ("Assa darlingtoni") guard their eggs, which are laid on the ground. When the eggs hatch, the male lubricates his body with the jelly surrounding them and immerses himself in the egg mass. The tadpoles wriggle into skin pouches on his side, where they develop until they metamorphose into juvenile frogs. The female gastric-brooding frog ("Rheobatrachus" sp.) from Australia, now probably extinct, swallows her fertilized eggs, which then develop inside her stomach. She ceases to feed and stops secreting stomach acid. The tadpoles rely on the yolks of the eggs for nourishment. After six or seven weeks, they are ready for metamorphosis. The mother regurgitates the tiny frogs, which hop away from her mouth. The female Darwin's frog ("Rhinoderma darwinii") from Chile lays up to 40 eggs on the ground, where they are guarded by the male. When the tadpoles are about to hatch, they are engulfed by the male, which carries them around inside his much-enlarged vocal sac. Here they are immersed in a frothy, viscous liquid that contains some nourishment to supplement what they obtain from the yolks of the eggs. They remain in the sac for seven to ten weeks before undergoing metamorphosis, after which they move into the male's mouth and emerge.
Phyllobates sp. aff. aurotaenia
All "Phyllobates" species are highly toxic, and "P." sp. aff." aurotaenia" is no exception. Its skin contains batrachotoxins, extremely potent neurotoxic alkaloids. When in contact with the skin, batrachotoxins seep through open wounds and, in some cases, skin pores, and prevent nerves from transmitting impulses, leaving the muscles in an inactive state of contraction. This can lead to heart failure or fibrillation. Some native people use this poison to hunt by coating darts with the frogs' poison. Alkaloid batrachotoxins can be stored by frogs for years after the frog is deprived of the food-based source, and such toxins do not readily deteriorate, even when transferred to another surface. Chickens and dogs have died from contact with a paper towel on which the more toxic "P. terribilis" had walked.
Limnodynastes
Limnodynastes (commonly known as the Australian swamp frogs) is a genus of frog native to Australia, southern New Guinea and some Torres Strait Islands. They are ground-dwelling frogs, with no toe pads. The size varies from 45 mm to 90 mm in the giant banjo frog. The webbing on the feet ranges between species, from very little, to almost complete. The tympanum is not visible in any species, except in the woodworker frog, which is sometimes classed in a separate genus "Megistolotis". All species construct a foam nest in which the eggs are laid. However, in south-eastern South Australia female striped marsh frog and spotted grass frog lack the flanges of skin on the hands that helps trap the air bubble and do not construct foam nests.
Trilling frog
The Trilling frog is adapted to desert conditions and can spend years without having to surface, buried deep underground with their glands under the skin full of water.
The Trilling Frogs will commonly dig themselves to the surface at the beginning of the late summer rains. There are stories that to prevent death by thirst, Indigenous Australians could catch these frogs by cleverly stamping on the right patch of ground to simulate thunder or falling rain, causing the frogs to surface where they could then be made to give up their stored moisture.
These frogs will spend a few weeks calling nightly while floating in or sitting at the edge of rainwater filled claypans, puddles and waterholes. 
DEH, Trilling Frog Call
Ancyronyx
The larvae are exclusively aquatic. They breathe by means of tracheal gills. Spider water beetle adults, like all members of the subfamily Elminae, can also remain indefinitely underwater by means of a plastron, a thin film of gas trapped by hydrophobic bristles (setae) on their body. As the insect breathes, the oxygen concentration in the gas film drops in comparison to the surrounding water, causing new oxygen to diffuse again into the plastron.
Green-eyed tree frog
Peptides found within the skin of frogs, including the green-eyed species, are now being looked to for HIV virus prevention. The chemicals found within their skin aren't pleasant for their predators, but can be very useful when fighting against bacteria, viruses, and fungus. When in dendritic cells, it has been found that the virus can still be killed by these peptides, showing a promise for mucosal preventatives. What is needed now, is the identification of which peptides can exactly prevent HIV in order to put this to work.
Xenopus
All species of "Xenopus" have flattened, somewhat egg-shaped and streamlined bodies, and very slippery skin (because of a protective mucus covering). The frog's skin is smooth, but with a lateral line sensory organ that has a stitch-like appearance. The frogs are all excellent swimmers and have powerful, fully webbed toes, though the fingers lack webbing. Three of the toes on each foot have conspicuous black claws.
Western clawed frog
In the dry season, this frog lives in shallow streams and hides under tree roots, under flat stones, or in holes in the riverbank. It feeds primarily on earthworms, insect larvae and tadpoles. When the rainy season starts it migrates across the forest floor at night to find temporary pools. Spawning may take place in large pools with much vegetation, but tadpoles are also sometimes found in muddy pools with no vegetation. Single eggs may be attached to plants or they may float. The tadpoles have broad mouths and no jaws, but have long tentacles on their upper lips. The ventral fins of their tails are broader than the dorsal ones. Their body colour is generally orange and the tail transparent but in darker locations the tail may be blackish. The tadpoles feed by filtering zooplankton from the water. In large water bodies, they may form dense swarms. Metamorphosis takes place when the tadpoles measure about in length.
Frog
A frog's skin is protective, has a respiratory function, can absorb water and helps control body temperature. It has many glands, particularly on the head and back, which often exude distasteful and toxic substances (granular glands). The secretion is often sticky and helps keep the skin moist, protects against the entry of moulds and bacteria, and make the animal slippery and more able to escape from predators. The skin is shed every few weeks. It usually splits down the middle of the back and across the belly, and the frog pulls its arms and legs free. The sloughed skin is then worked towards the head where it is quickly eaten.
Spawn (biology)
While the length of the egg stage depends on the species and environmental conditions, aquatic eggs generally hatch within one week. Unlike salamanders and newts, frogs and toads never become sexually mature while still in their larval stage. The hatched eggs continue life as tadpoles, which typically have oval bodies and long, vertically flattened tails. As a general rule, free living larvae are fully aquatic. They lack eyelids and have a cartilaginous skeleton, a lateral line system, gills for respiration (external gills at first, internal gills later) and tails with dorsal and ventral folds of skin for swimming. They quickly develop a gill pouch that covers the gills and the front legs; the lungs are also developed at an early stage as an accessory breathing organ. Some species which go through the metamorphosis inside the egg and hatch to small frogs never develop gills; instead there are specialised areas of skin that take care of respiration. Tadpoles also lack true teeth, but the jaws in most species usually have two elongate, parallel rows of small keratinized structures called keradonts in the upper jaw while the lower jaw has three rows of keradonts, surrounded by a horny beak, but the number of rows can be lower (sometimes zero), or much higher. Tadpoles feed on algae, including diatoms filtered from the water through the gills. Some species are carnivorous at the tadpole stage, eating insects, smaller tadpoles, and fish. Cannibalism has been observed among tadpoles. Early developers who gain legs may be eaten by the others, so the late bloomers survive longer.
Respiratory system
In most fish, and a number of other aquatic animals (both vertebrates and invertebrates) the respiratory system consists of gills, which are either partially or completely external organs, bathed in the watery environment. This water flows over the gills by a variety of active or passive means. Gas exchange takes place in the gills which consist of thin or very flat filaments and lammelae which expose a very large surface area of highly vascularized tissue to the water.
Cranwell's horned frog
At extreme temperatures, Cranwell's frogs enter a period of estivation, developing a thick layer of protective skin to trap moisture and aid in respiration. When estivation is complete, the frog uses its front and hind legs to help shed the protective layer. In many cases, the frog uses its jaws to help pull the skin over its back, often eating the skin in the process.
Frog
Some frogs have become adapted for burrowing and a life underground. They tend to have rounded bodies, short limbs, small heads with bulging eyes, and hind feet adapted for excavation. An extreme example of this is the purple frog ("Nasikabatrachus sahyadrensis") from southern India which feeds on termites and spends almost its whole life underground. It emerges briefly during the monsoon to mate and breed in temporary pools. It has a tiny head with a pointed snout and a plump, rounded body. Because of this fossorial existence, it was first described in 2003, being new to the scientific community at that time, although previously known to local people.
The spadefoot toads of North America are also adapted to underground life. The Plains spadefoot toad ("Spea bombifrons") is typical and has a flap of keratinised bone attached to one of the metatarsals of the hind feet which it uses to dig itself backwards into the ground. As it digs, the toad wriggles its hips from side to side to sink into the loose soil. It has a shallow burrow in the summer from which it emerges at night to forage. In winter, it digs much deeper and has been recorded at a depth of . The tunnel is filled with soil and the toad hibernates in a small chamber at the end. During this time, urea accumulates in its tissues and water is drawn in from the surrounding damp soil by osmosis to supply the toad's needs. Spadefoot toads are "explosive breeders", all emerging from their burrows at the same time and converging on temporary pools, attracted to one of these by the calling of the first male to find a suitable breeding location.
Tubifex tubifex
The worms can survive with little oxygen by waving hemoglobin-rich tail ends to exploit all available oxygen, and can exchange carbon dioxide and oxygen through their thin skins, in a manner similar to frogs. They can also survive in areas heavily polluted with organic matter that almost no other species can endure. By forming a protective cyst and lowering its metabolic rate, "T. tubifex" can survive drought and food shortage. Encystment may also function in the dispersal of the worm.
They usually inhabit the bottom sediments of lakes, rivers, and occasionally sewer lines and outlets.
Excretory system
In mammals. the skin excretes sweat through sweat glands throughout the body. The sweat, helped by salt, evaporates and helps to keep the body cool when it is warm. In amphibians, the lungs are very simple, and they lack the necessary means to the exhale like other tetrapods can. The moist, scale-less skin is therefore essential in helping to rid the blood of carbon dioxide, and also allows for urea to be expelled through diffusion when submerged.
Cockroach
Like other insects, cockroaches breathe through a system of tubes called tracheae which are attached to openings called spiracles on all body segments. When the carbon dioxide level in the insect rises high enough, valves on the spiracles open and carbon dioxide diffuses out and oxygen diffuses in. The tracheal system branches repeatedly, the finest tracheoles bringing air directly to each cell, allowing gaseous exchange to take place.
Concave-eared torrent frog
Concave-eared torrent frog is the first frog (and the first non-mammalian vertebrate) demonstrated to both produce and perceive ultrasonic frequencies. These frogs' preferred habitat is adjacent to rapidly moving water which produces perpetual low-frequency background noise. Thus, the use of high-frequency calls is believed to facilitate intraspecific communication within the frogs' noisy environment.
Frog
An adult frog has a stout body, protruding eyes, cleft tongue, limbs folded underneath, and no tail. Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skins varies in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to show toxicity and ward off predators. Adult frogs live in fresh water and on dry land; some species are adapted for living underground or in trees.
Cutaneous respiration
Some amphibians utilizing cutaneous respiration have extensive folds of skin to increase the rate of respiration. Examples include the hellbender salamander and the Lake Titicaca water frog. Cutaneous respiration in hellbenders accounts for more than 90 percent of oxygen uptake and carbon dioxide excretion.
Palaeobatrachus
These frogs lived permanently in water. Their bag-shaped lungs, on the dorsal side of their body, enabled them to remain submerged for long periods. They inhabited through-drainage basins or swamps where brown coal deposits were formed. Like the African clawed toad, they probably lived on small crustaceans, insect larvae and small fish and themselves provided sustenance for many other animals.
Frog
After metamorphosis, young adults may disperse into terrestrial habitats or continue to live in water. Almost all frog species are carnivorous as adults, preying on invertebrates, including arthropods, worms, snails, and slugs. A few of the larger ones may eat other frogs, small mammals, and fish. Some frogs use their sticky tongues to catch fast-moving prey, while others push food into their mouths with their hands. A few species also eat plant matter; the tree frog "Xenohyla truncata" is partly herbivorous, its diet including a large proportion of fruit, "Leptodactylus mystaceus" has been found to eat plants, and folivory occurs in "Euphlyctis hexadactylus", with plants constituting 79.5% of its diet by volume. Adult frogs are themselves attacked by many predators. The northern leopard frog ("Rana pipiens") is eaten by herons, hawks, fish, large salamanders, snakes, raccoons, skunks, mink, bullfrogs, and other animals.
Frogs are primary predators and an important part of the food web. Being cold-blooded, they make efficient use of the food they eat with little energy being used for metabolic processes, while the rest is transformed into biomass. They are themselves eaten by secondary predators and are the primary terrestrial consumers of invertebrates, most of which feed on plants. By reducing herbivory, they play a part in increasing the growth of plants and are thus part of a delicately balanced ecosystem.
Balloon syndrome
In July 2017 Live Science reported Romain Pizzi, the specialist wildlife veterinary surgeon at the Scottish Society for the Prevention of Cruelty to Animals (Scottish SPCA), saying that, "Hedgehogs have a little windpipe that runs from their mouth and nose to their lungs, and at the top of this windpipe is the glottis, which opens and closes as hedgehogs breathe. ... If a hedgehog is struck when that glottis is open, air simply flows out of the lungs and out of the body. But if the glottis is closed when the animal is struck, that air has nowhere to go, and the lung tissue can rupture. It's like a balloon popping. ... This trauma can also cause damage to the muscles in between a hedgehog's ribs". Live Science added that "the ruptures in the lungs and rib muscles [according to Pizzi] 'act like a one-way valve,' so air can flow out of the lungs and into the body cavity—but not back in. So, with each breath the hedgehog takes, a bit of air leaks out, causing the hedgehog to inflate itself. ... Pizzi noted that the tissue under a hedgehog's skin isn't designed to be filled with air, so it's not one big open compartment. Instead, there is a lot of connective tissue under the skin, sectioning areas off into little compartments of air. Though it's called balloon syndrome, in most cases the hedgehogs 'puff up more like Bubble Wrap,' he said".
Tetrapod
Although air-breathing fish can absorb oxygen through their lungs, the lungs tend to be ineffective for discharging carbon dioxide. In tetrapods, the ability of lungs to discharge CO came about gradually, and was not fully attained until the evolution of amniotes. The same limitation applies to gut air breathing (GUT), i.e., breathing with the lining of the digestive tract. Tetrapod skin would have been effective for both absorbing oxygen and discharging CO, but only up to a point. For this reason, early tetrapods may have experienced chronic hypercapnia (high levels of blood CO). This is not uncommon in fish that inhabit waters high in CO.
According to one hypothesis, the "sculpted" or "ornamented" dermal skull roof bones found in early tetrapods may have been related to a mechanism for relieving respiratory acidosis (acidic blood caused by excess CO) through compensatory metabolic alkalosis.
Damselfly
The nymphs are voracious predators and feed by means of a flat labium (a toothed mouthpart on the lower jaw) that forms the so-called mask; it is rapidly extended to seize and pierce the "Daphnia" (water fleas), mosquito larvae, and other small aquatic organisms on which damselfly nymphs feed. They breathe by means of three large external, fin-like gills on the tip of the abdomen, and these may also serve for locomotion in the same manner as a fish's tail. Compared to dragonfly larvae, the nymphs show little variation in form. They tend to be slender and elongate, many having morphological adaptations for holding their position in fast flowing water. They are more sensitive than dragonfly nymphs to oxygen levels and suspended fine particulate matter, and do not bury themselves in the mud.
Frog
In many arboreal frogs, a small "intercalary structure" on each toe increases the surface area touching the substrate. Furthermore, since hopping through trees can be dangerous, many arboreal frogs have hip joints to allow both hopping and walking. Some frogs that live high in trees even possess an elaborate degree of webbing between their toes. This allows the frogs to "parachute" or make a controlled glide from one position in the canopy to another.
Breviceps adspersus
The common rain frog lives underground, only emerging to feed and mate after a rain, usually at nighttime. Its body is stout and globular, with a flattened face. The color of this species is either light or dark brown, with rows of lighter yellow orange patches, with darker borders. It also has the short, stout limbs typical of most burrowing frogs and toads. However, its back feet are like spades and are able to dig up to 20 inches below ground. If attacked, the frog inflates and lodges itself firmly inside of the burrow. The females are also much larger than males. Since the male cannot grip the female during mating because of the size difference, the female secretes a kind of glue from her back to keep the mating pair together. The stuck-together pair burrow backwards into the soil until they reach a moist spot. Once a suitable spot is reached, the female lays her eggs. The eggs hatch directly into froglets instead of tadpoles. They are 1½ to 2¼ inches long (3 to 6 centimeters).
Spotted grass frog
The male and female frogs can be sexed by the presence of a flap of skin around the thumbs of the females. This is used to froth the water during amplexus to create the floating foamy nest that it lays eggs in, which is roughly the size of a human palm. The tadpoles of this frog are comparatively large (up to 6 cm). This frog spends a minimum of 3 months in the tadpole stage.
African dwarf frog
All species of Pipidae are tongueless, toothless, and completely aquatic. They use their webbed feet to shove food in their mouths and down their throats, and a hyobranchial pump to draw or suck food into their mouths. Pipidae have powerful legs for swimming and lunging after food. They also use the claws on their feet to tear pieces of large food. They lack true ears, but have lateral lines running down the length of their bodies and undersides; this is how they can sense movements and vibration in the water. They use their sensitive fingers, sense of smell, and lateral line system to find food. They are scavengers and will eat anything living, dying, or dead and any type of organic detritus.
Frog
When frogs mate, the male climbs on the back of the female and wraps his fore limbs round her body, either behind the front legs or just in front of the hind legs. This position is called amplexus and may be held for several days. The male frog has certain hormone-dependent secondary sexual characteristics. These include the development of special pads on his thumbs in the breeding season, to give him a firm hold. The grip of the male frog during amplexus stimulates the female to release eggs, usually wrapped in jelly, as spawn. In many species the male is smaller and slimmer than the female. Males have vocal cords and make a range of croaks, particularly in the breeding season, and in some species they also have vocal sacs to amplify the sound.
Frog
Frogs live on all the continents except Antarctica, but they are not present on certain islands, especially those far away from continental land masses. Many species are isolated in restricted ranges by changes of climate or inhospitable territory, such as stretches of sea, mountain ridges, deserts, forest clearance, road construction, or other man-made barriers. Usually, a greater diversity of frogs occurs in tropical areas than in temperate regions, such as Europe. Some frogs inhabit arid areas, such as deserts, and rely on specific adaptations to survive. Members of the Australian genus "Cyclorana" bury themselves underground where they create a water-impervious cocoon in which to aestivate during dry periods. Once it rains, they emerge, find a temporary pool, and breed. Egg and tadpole development is very fast in comparison to those of most other frogs, so breeding can be completed before the pond dries up. Some frog species are adapted to a cold environment. The wood frog ("Rana sylvatica"), whose habitat extends into the Arctic Circle, buries itself in the ground during winter. Although much of its body freezes during this time, it maintains a high concentration of glucose in its vital organs, which protects them from damage.
Frog
During the evolutionary history of frogs, several different groups have independently taken to the air. Some frogs in the tropical rainforest are specially adapted for gliding from tree to tree or parachuting to the forest floor. Typical of them is Wallace's flying frog ("Rhacophorus nigropalmatus") from Malaysia and Borneo. It has large feet with the fingertips expanded into flat adhesive discs and the digits fully webbed. Flaps of skin occur on the lateral margins of the limbs and across the tail region. With the digits splayed, the limbs outstretched, and these flaps spread, it can glide considerable distances, but is unable to undertake powered flight. It can alter its direction of travel and navigate distances of up to between trees.
Frog Skin
Frog Skin is a battledress camouflage pattern with mottle and disruptive coloration to blend into the environment similar to a frog's crypsis skin.
Common frog
Common frogs metamorphose through three distinct developmental life stages — aquatic larva, terrestrial juvenile, and adult. They have corpulent bodies with a rounded snout, webbed feet and long hind legs adapted for swimming in water and hopping on land. Common frogs are often confused with the common toad "Bufo bufo", but frogs can easily be distinguished as they have longer legs, hop, and have a moist skin, whereas toads crawl and have a dry 'warty' skin. The spawn of the two species also differs in that frogspawn is laid in clumps and toadspawn is laid in long strings.
Shovelnose frog
The shovelnose frogs are burrowing frogs, living most of their lives underground. The female digs underground while in amplexus, and lays her eggs in an underground cavity. The male leaves through the tunnel, and the female remains with the eggs. Once sufficient rain has fallen, the female burrows with her nose towards a water source, where the tadpoles will remain until metamorphosis. The tadpoles may remain out of water up to a few days.
Bornean flat-headed frog
Djoko Iskandar, an Indonesian zoologist, first described the Bornean flat-headed frog based on a single specimen. However, he did not know the frog was lungless until he was in the field with David Bickford's expedition. Bickford "et al." were able to dissect some of the specimens and discovered for the first time that the frogs had no lungs. The frog breathes entirely through its skin, and its internal organs (the stomach, spleen and the liver) take up much of the space which normally would be filled by the lungs. By retaining the lunglessness of their tadpole stage, the frogs are much flatter than typical frogs, which might help absorb oxygen and avoid being swept away in fast streams.
Epicauta vittata
Frogs are apparently not affected by Meloidae beetle toxin, and "consume meloids with impunity". After eating blister beetles, frogs retain the toxin in their tissues and secrete it in their mucus for a short time, and predators that consume the frogs can be poisoned. This includes humans who consume foods such as frog legs. Northern leopard frogs fed striped blister beetles in studies accumulated cantharidin in their thigh muscles, among other tissues. It is estimated that as little as 200 grams of frog legs from beetle-fed frogs could contain a potentially fatal dose of toxin.
Frog
Camouflage is a common defensive mechanism in frogs. Most camouflaged frogs are nocturnal; during the day, they seek out a position where they can blend into the background and remain undetected. Some frogs have the , but this is usually restricted to a small range of colours. For example, White's tree frog ("Litoria caerulea") varies between pale green and dull brown according to the temperature, and the Pacific tree frog ("Pseudacris regilla") has green and brown morphs, plain or spotted, and changes colour depending on the time of year and general background colour. Features such as warts and skin folds are usually on ground-dwelling frogs, for whom smooth skin would not provide such effective camouflage. Certain frogs change colour between night and day, as light and moisture stimulate the pigment cells and cause them to expand or contract.
The skin of a frog is permeable to oxygen and carbon dioxide, as well as to water. There are blood vessels near the surface of the skin and when a frog is underwater, oxygen diffuses directly into the blood. When not submerged, a frog breathes by a process known as buccal pumping. Its lungs are similar to those of humans, but the chest muscles are not involved in respiration, and no ribs or diaphragm exist to help move air in and out. Instead, it puffs out its throat and draws air in through the nostrils, which in many species can then be closed by valves. When the floor of the mouth is compressed, air is forced into the lungs. The fully aquatic Bornean flat-headed frog ("Barbourula kalimantanensis") is the first frog known to lack lungs entirely.
Myobatrachidae
These frogs lack adhesive toe discs found in the tree frogs. The family is broken into subfamilies based mainly upon their egg-laying habits. Those of the subfamily Limnodynastinae lay foam nests. The female creates foam by agitating a chemical on her skin with her hands. The foam may float on top of water, or be on land. The subfamily Rheobatrachinae contains the two species of gastric-brooding frogs, and the rest are within the subfamily Myobatrachinae.
Hairy frog
The hairy frog is also notable in possessing retractable "claws" (though unlike true claws, they are made of bone, not keratin), which it may project through the skin, apparently by intentionally breaking the bones of the toe. In addition, the researchers found a small bony nodule nestled in the tissue just beyond the frog's fingertip. When sheathed, each claw is anchored to the nodule with tough strands of collagen, but, as Gerald Durrell discovered firsthand, when the frog is grabbed or attacked, the frog breaks the nodule connection and forces its sharpened bones through the skin.
Cutaneous respiration
Mammals are endotherms, ("warm-blooded") and have higher metabolic demands than ectothermic ("cold-blooded") vertebrates, and the skin is thicker and more impermeable than other vertebrates, which preclude the skin as a major source of gas exchange. However, small amounts of respiration may occur, and in bats, the highly vascularized wings may account for up to 12 percent of carbon dioxide excretion. In humans and most other mammals, cutaneous respiration accounts for only 1 to 2 percent.
Amphibian
The order Anura (from the Ancient Greek "a(n)-" meaning "without" and "oura" meaning "tail") comprises the frogs and toads. They usually have long hind limbs that fold underneath them, shorter forelimbs, webbed toes with no claws, no tails, large eyes and glandular moist skin. Members of this order with smooth skins are commonly referred to as frogs, while those with warty skins are known as toads. The difference is not a formal one taxonomically and there are numerous exceptions to this rule. Members of the family Bufonidae are known as the "true toads". Frogs range in size from the Goliath frog ("Conraua goliath") of West Africa to the "Paedophryne amauensis", first described in Papua New Guinea in 2012, which is also the smallest known vertebrate. Although most species are associated with water and damp habitats, some are specialised to live in trees or in deserts. They are found worldwide except for polar areas.
Pain in amphibians
The skin of frogs contains both Group C fibres and A-delta fibres.
Frog
Frogs in the genera "Heleioporus" and "Neobatrachus" lack vocal sacs but can still produce a loud call. Their buccal cavity is enlarged and dome-shaped, acting as a resonance chamber that amplifies the sound. Species of frog that lack vocal sacs and that do not have a loud call tend to inhabit areas close to constantly noisy, flowing water. They need to use an alternative means to communicate. The coastal tailed frog ("Ascaphus truei") lives in mountain streams in North America and does not vocalize.
List of amphibians of Guatemala
The true frogs, family Ranidae, have the widest distribution of any frog family. They are abundant throughout most of the world, occurring on all continents except Antarctica. Typically, true frogs are smooth, moist-skinned frogs, with large, powerful legs and extensively webbed feet. True frogs vary greatly in size, ranging from small—such as the Wood Frog ("Rana sylvatica")—to the largest frog in the world, the Goliath frog ("Conraua goliath"). 
Many of the true frogs are aquatic or live close to water. Most species lay their eggs in the water and go through a tadpole stage. However, as with most families of frogs, there is large variation of habitat within the family. Those of the genus "Tomopterna" are burrowing frogs native to Africa and exhibit most of the characteristics common to burrowing frogs around the world. There are also arboreal species of true frogs, and the family includes some of the very few amphibians that can live in brackish water. There are 6 species in Guatemala.
Frog
Frogs have served as experimental animals throughout the history of science. Eighteenth-century biologist Luigi Galvani discovered the link between electricity and the nervous system by studying frogs. In 1852, H. F. Stannius used a frog's heart in a procedure called a Stannius ligature to demonstrate the ventricle and atria beat independently of each other and at different rates. The African clawed frog or platanna ("Xenopus laevis") was first widely used in laboratories in pregnancy tests in the first half of the 20th century. A sample of urine from a pregnant woman injected into a female frog induces it to lay eggs, a discovery made by English zoologist Lancelot Hogben. This is because a hormone, human chorionic gonadotropin, is present in substantial quantities in the urine of women during pregnancy. In 1952, Robert Briggs and Thomas J. King cloned a frog by somatic cell nuclear transfer. This same technique was later used to create Dolly the sheep, and their experiment was the first time a successful nuclear transplantation had been accomplished in higher animals.
Lithobates heckscheri
Adult river frogs have a home range of about . They are largely nocturnal and feed on insects and other invertebrates, as well as small vertebrates, including frogs. They spend much of their time in water and are relatively bold. During hot weather they are normally found sitting in moist or wet places, presumably to avoid desiccation. When the temperature falls below about they are no longer to be seen in their normal habitat and are likely to be seeking refuge from the cold under water.
Breeding takes place between April and August with males calling from the edge of ponds and swamps from April to July. The call has been described as "a deep, low-pitched, rolling snore". The eggs are laid in a floating layer among emergent vegetation, a clutch numbering several thousand eggs which hatch after about three days. The tadpoles are at first a dark color but become much paler over time with a dark edge to the tail fin. They congregate in the shallows in the daytime, sometimes in dense swarms, but move into deep water at night. They feed on both animal and vegetable matter. They remain as tadpoles for a long period, overwintering once or twice, and reaching a snout-to-vent length of or more. After metamorphosis, the newly emerged juveniles are long and move away from the margins of the water. The large number of juveniles compared to the relatively small number of adults indicates a high mortality rate for newly emerged young. Predators that feed on tadpoles and juveniles are thought to include the banded water snake ("Nerodia fasciata"), other water snakes ("Nerodia" sp.), the largemouth bass ("Micropterus salmoides") and the grackle ("Quiscalus" sp.). However the skin may contain some noxious substances or malodorous secretions as some snakes, including the indigo snake ("Drymarchon"), have been observed gagging and retching after eating a river frog. Even after the frog has been regurgitated, the snake continued to wipe its mouth on the ground.
Orbiting Frog Otolith
Both flight frogs had electrocardiogram (ECG) electrodes implanted in their thoracic cavities and microelectrodes implanted in their vestibular nerves. The frogs were demotorized by cutting their limb nerves to prevent them from dislodging their implanted electrodes, and to reduce their metabolic rates. With this lowered metabolic activity, the frogs could survive in good health without being fed for as long as one month. Immersion in water allowed the frogs to breathe through their skin. The water medium also helped to move carbon dioxide and heat away from the animals.
Dolomedes
"Dolomedes" spiders are covered all over in short, velvety hairs which are unwettable (hydrophobic). This allows them to use surface tension to stand or run on the water, like pond skaters. They can also climb beneath the water, and then air becomes trapped in the body hairs and forms a thin film over the whole surface of the body and legs, giving them the appearance of fine polished silver. Like other spiders, "Dolomedes" breathe with book lungs beneath their abdomens, and these open into the air film, allowing the spiders to breathe while submerged. The trapped air makes them very buoyant and if they do not hold onto a rock or a plant stem they float to the surface where they pop onto the surface film, completely dry.
Vocal sac
The vocal sac is open to the mouth cavity of the frog, with two slits on either side of the tongue. To call, the frog inflates its lungs and shuts its nose and mouth. Air is then expelled from the lungs, through the larynx, and into the vocal sac. The vibrations of the larynx emits a sound, which resonates within the vocal sac. The resonance causes the sound to be amplified and allows the call to carry further. Muscles within the body wall force the air back and forth between the lungs and vocal sac.
True frog
Many of the true frogs are aquatic or live close to water. Most species lay their eggs in the water and go through a tadpole stage. However, as with most families of frogs, there is large variation of habitat within the family. Those of the genus "Tomopterna" are burrowing frogs native to Africa and exhibit most of the characteristics common to burrowing frogs around the world. There are also arboreal species of true frogs, and the family includes some of the very few amphibians that can live in brackish water.
Frog
Sometimes during the tadpole stage, one of the developing rear legs is eaten by a predator such as a dragonfly nymph. In some cases, the full leg still grows, but in others it does not, although the frog may still live out its normal lifespan with only three limbs. Occasionally, a parasitic flatworm ("Ribeiroia ondatrae") digs into the rear of a tadpole, causing a rearrangement of the limb bud cells and the frog develops an extra leg or two.
Orbiting Frog Otolith
The frogs, housed in the centrifuge, are in the liquid loop. Moving from the lung to the frogs, the loop contains water and dissolved oxygen; moving from the frogs back to the lung, it contains water and free CO. A double layer of polyurethane foam lining the interior of the centrifuge prevents frog waste matter from fouling the water circulation system. Water is circulated through the liquid loop using a small pump and must pass through the filter before leaving the centrifuge.
Frog
Many frogs are able to absorb water and oxygen directly through the skin, especially around the pelvic area, but the permeability of a frog's skin can also result in water loss. Glands located all over the body exude mucus which helps keep the skin moist and reduces evaporation. Some glands on the hands and chest of males are specialized to produce sticky secretions to aid in amplexus. Similar glands in tree frogs produce a glue-like substance on the adhesive discs of the feet. Some arboreal frogs reduce water loss by having a waterproof layer of skin, and several South American species coat their skin with a waxy secretion. Other frogs have adopted behaviours to conserve water, including becoming nocturnal and resting in a water-conserving position. Some frogs may also rest in large groups with each frog pressed against its neighbours. This reduces the amount of skin exposed to the air or a dry surface, and thus reduces water loss. Woodhouse's toad ("Bufo woodhousii"), if given access to water after confinement in a dry location, sits in the shallows to rehydrate. The male hairy frog ("Trichobatrachus robustus") has dermal papillae projecting from its lower back and thighs, giving it a bristly appearance. They contain blood vessels and are thought to increase the area of the skin available for respiration.
Pickerel frog
In case of attack, pickerel frogs have an excellent defense mechanism: they emit skin secretions which are irritating to people and toxic to some predators; making the pickerel frog the only poisonous frog native to the United States. Due to its poison, most mammals, birds, snakes and other frogs will leave the pickerel frog alone. The skin secretions of a stressed pickerel frog are known to be toxic to other frogs, as many a novice frog catcher has found when he finds only the pickerel frog still alive in his bucket. These secretions can also be moderately irritating if they come in contact with the eyes, mucous membranes, or broken skin.
Aquatic respiration
Both the lungs and the skin serve as respiratory organs in amphibians. The skin of these animals is highly vascularized and moist, with moisture maintained via secretion of mucus from specialized cells. While the lungs are of primary importance to breathing control, the skin's unique properties aid rapid gas exchange when amphibians are submerged in oxygen-rich water.
Frog
Frogs typically lay their eggs in water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on fruit. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce a wide range of vocalizations, particularly in their breeding season, and exhibit many different kinds of complex behaviours to attract mates, to fend off predators and to generally survive.
List of herpetofauna of the Czech Republic
Amphibians are tetrapod animals from the class Amphibia comprising toads, frogs, salamanderns, newts and caecilians. They have an amphibious lifestyle, where the larvae are aquatic. Skin is generally soft and with glands. They show three type of respiration through moist skin, buccal cavity and lungs. Caecilians are limbless amphibians, whereas other amphibians have short limbs. Amphibians lay cluster of eggs as egg masses closer to a water body and show an external fertilization.
Italian crested newt
Respiration in newts can take place through the skin, the lungs, or the buccal cavity, but newts mainly respire through the skin due to the fact that the buccal cavity and lungs are poorly vascularized. However, when "T. carnifex" are placed in poorly oxygenized water, they switch their primary respiratory surface from skin to lungs. Through further tests it was shown that "T. carnifex" can stay under water for long periods of time by using their skin to respire, but when they become active they must switch and usetilize their lungs or buccal cavity. Eddy and McDonald (1977) also discovered that many nsetilize their lungs to help regulate their buoyancy, similar to fish that use a swim bladder to aid in swimming.
Megalodiscus temperatus
The reproduction of "Megalodiscus temperatus" are displayed in the stomach and rectum of frogs and tadpoles. The snails that are diffused with miracidia releases cercariae into the water to penetrate the skin of frogs. The frogs regularly cast off the outer layers of the skin which results in their exposure to metaceriae. The metaceriae remains in the rectum of the frog and matures in the time span of four months. Tadpoles are less commonly infected, but when infected they are infected by the ingestion of cercaria. Through the process of metaphorphosis, "Megalodiscus temperatus" travels primarily from the anterior to the posterior of the rectum.
Armadillidium
Unlike other terrestrial arthropods such as insects and spiders, pill bugs do not have a waxy cuticle that would reduce evaporation from their bodies. Pill bugs also use modified lungs, called pseudotrachea, for respiration, and the lungs must remain moist to function. Individual pill bugs typically live for two or three years, and females brood eggs once or twice each summer. Several hundred eggs are brooded at a time in the marsupium, a pocket on the ventral side of the female pill bug. The marsupium must also be kept filled with water until the young hatch and crawl away.
Frog
At the end of the tadpole stage, a frog undergoes metamorphosis in which its body makes a sudden transition into the adult form. This metamorphosis typically lasts only 24 hours, and is initiated by production of the hormone thyroxine. This causes different tissues to develop in different ways. The principal changes that take place include the development of the lungs and the disappearance of the gills and gill pouch, making the front legs visible. The lower jaw transforms into the big mandible of the carnivorous adult, and the long, spiral gut of the herbivorous tadpole is replaced by the typical short gut of a predator. The nervous system becomes adapted for hearing and stereoscopic vision, and for new methods of locomotion and feeding. The eyes are repositioned higher up on the head and the eyelids and associated glands are formed. The eardrum, middle ear, and inner ear are developed. The skin becomes thicker and tougher, the lateral line system is lost, and skin glands are developed. The final stage is the disappearance of the tail, but this takes place rather later, the tissue being used to produce a spurt of growth in the limbs. Frogs are at their most vulnerable to predators when they are undergoing metamorphosis. At this time, the tail is being lost and locomotion by means of limbs is only just becoming established.
Frog
Because frog toxins are extraordinarily diverse, they have raised the interest of biochemists as a "natural pharmacy". The alkaloid epibatidine, a painkiller 200 times more potent than morphine is made by some species of poison dart frogs, although it can also cause death by lung paralysis. Other chemicals isolated from the skins of frogs may offer resistance to HIV infection. Dart poisons are under active investigation for their potential as therapeutic drugs.
Frog
Being cold-blooded, frogs have to adopt suitable behaviour patterns to regulate their temperature. To warm up, they can move into the sun or onto a warm surface; if they overheat, they can move into the shade or adopt a stance that exposes the minimum area of skin to the air. This posture is also used to prevent water loss and involves the frog squatting close to the substrate with its hands and feet tucked under its chin and body. The colour of a frog's skin is used for thermoregulation. In cool damp conditions, the colour will be darker than on a hot dry day. The grey foam-nest tree frog ("Chiromantis xerampelina") is even able to turn white to minimize the chance of overheating.
Amphibian
The lungs in amphibians are primitive compared to those of amniotes, possessing few internal septa and large alveoli, and consequently having a comparatively slow diffusion rate for oxygen entering the blood. Ventilation is accomplished by buccal pumping. Most amphibians, however, are able to exchange gases with the water or air via their skin. To enable sufficient cutaneous respiration, the surface of their highly vascularised skin must remain moist to allow the oxygen to diffuse at a sufficiently high rate. Because oxygen concentration in the water increases at both low temperatures and high flow rates, aquatic amphibians in these situations can rely primarily on cutaneous respiration, as in the Titicaca water frog and the hellbender salamander. In air, where oxygen is more concentrated, some small species can rely solely on cutaneous gas exchange, most famously the plethodontid salamanders, which have neither lungs nor gills. Many aquatic salamanders and all tadpoles have gills in their larval stage, with some (such as the axolotl) retaining gills as aquatic adults.
Common frog
Outside the breeding season, common frogs live a solitary life in damp places near ponds or marshes or in long grass. They are normally active for much of the year, only hibernating in the coldest months. In the most northern extremities of their range they may be trapped under ice for up to nine months of the year, but recent studies have shown that in these conditions they may be relatively active at temperatures close to freezing. In the British Isles, common frogs typically hibernate from late October to January. They will re-emerge as early as February if conditions are favourable, and migrate to bodies of water such as garden ponds to spawn. Where conditions are harsher, such as in the Alps, they emerge as late as early June. Common frogs hibernate in running waters, muddy burrows, or in layers of decaying leaves and mud at the bottom of ponds or lakes primarily with a current. The oxygen uptake through the skin suffices to sustain the needs of the cold and motionless frogs during hibernation.
Theloderma corticale
Theloderma corticale (common names: mossy frog, Vietnamese mossy frog, and Tonkin bug-eyed frog) is a species of frog in the family Rhacophoridae.
It is found in northern Vietnam and possibly in China and adjacent Laos.
The common name "mossy frog" arises from the fact that its skin is a mottled green and brown that resembles moss growing on rock, and forms an effective form of camouflage. They have large sticky pads on their toes and a soft underbelly. The females will grow larger than the males and can reach sizes of . This species will curl into a ball when frightened, and play dead.
Its natural habitats are primary evergreen rainforests. It is a semi-aquatic that is found in caves and steep rocky cliffs. Breeding takes place in rock cavities or tree holes.
Hyalinobatrachium fleischmanni
Also known as the Northern Glass Frog, this frog’s physical features include primarily green skin, pale yellowish spots, yellow fingertips and translucent skin covering its stomach. A sheet of guanine stretches over several internal organs, such as the heart, but leaves others parts such as the liver exposed for viewing as it only covers half of the frog’s underbelly. They also possess a white vocal sac that can be used to produce sounds for mating. Male frogs have a noticeable hook protruding from its spine, presumably used to fight other frogs, defend its territory or the eggs. They are fierce fighters who will occasionally engage in a wrestling match with other intruding frogs. The female species are slightly larger and lacks this particular feature. There have been more than 100 reported glass frogs throughout Central and South America. 13 species can be found in Costa Rica. Adults tend to be more active during the night when there is rain to keep their skin moist and from drying out. However, strong rains can kill them because their bodies are so fragile. A simple direct shot from a raindrop has been known to kill a glass frog.
Lung
Due to the possibility of respiration across the skin combined with small size, all known lungless tetrapods are amphibians. The majority of salamander species are lungless salamanders, which respirate through their skin and tissues lining their mouth. This necessarily restrict their size: all are small and rather thread-like in appearance, maximising skin surface relative to body volume. Other known lungless tetrapods are the Bornean flat-headed frog and "Atretochoana eiselti", a caecilian.
Skin
Fur is dense hair. Primarily, fur augments the insulation the skin provides but can also serve as a secondary sexual characteristic or as camouflage. On some animals, the skin is very hard and thick, and can be processed to create leather. Reptiles and fish have hard protective scales on their skin for protection, and birds have hard feathers, all made of tough β-keratins. Amphibian skin is not a strong barrier, especially regarding the passage of chemicals via skin and is often subject to osmosis and diffusive forces. For example, a frog sitting in an anesthetic solution would be sedated quickly, as the chemical diffuses through its skin. Amphibian skin plays key roles in everyday survival and their ability to exploit a wide range of habitats and ecological conditions.
Parborlasia corrugatus
Although this creature does not have a dedicated respiratory system, "Parborlasia corrugatus" is able to obtain oxygen by absorbing it through its skin. An animal of its size would typically find it difficult to receive enough oxygen this way, but this worm has a low metabolic rate, and also enjoys the advantage of its environment, which is cold, oxygen-rich Antarctic waters. When "Parborlasia corrugatus" experiences lower levels of oxygen in the water, it flattens and elongates its body to aid in the uptake of oxygen by increasing its skin area. This manoevre also reduces the distance that the oxygen must travel to diffuse into its body.
Amazon basin
More than 1,500 species of amphibians swim and are found in the Amazon. Unlike temperate frogs which are mostly limited to habitats near the water, tropical frogs are most abundant in the trees and relatively few are found near bodies of water on the forest floor. The reason for this occurrence is quite simple: frogs must always keep their skin moist since almost half of their respiration is carried out through their skin. The high humidity of the rainforest and frequent rainstorms gives tropical frogs infinitely more freedom to move into the trees and escape the many predators of rainforest waters. The differences between temperate and tropical frogs extend beyond their habitat.
Green mantella
They also eat soft fruit. Green mantella require water, as most frogs do, but do not get it by drinking. Their permeable skin allows them to absorb the water.
African dwarf frog
African dwarf frogs live their entire lives underwater but need to rise to the surface to breathe air because they have lungs and not gills. These frogs are small in size and do not weigh more than a few grams. They vary in color, mostly ranging from olive green to brown with black spots. The average life expectancy of these frogs is five years, but they can live as long as 20 years, and they can grow to 3 inches (7.5 cm) long. When young, African dwarf frogs can be mistaken for and sold as African clawed frogs, of the genus "Xenopus", which are larger and more aggressive than the dwarf.
Hyperolius nitidulus
"Hyperolius nitidulus" live in an environment with a wet season that can be cold and humid, and an extremely hot and dry season. During the hot and dry season the frog is dependent on water therefore it has special adaptations to survive the extreme climate. "Hyperolius nitidulus" is known for its unique aestivation behavior during the hot and dry season. During dry season "Hyperolius nitidulus" do not seek shelter or hide, instead, they fully expose themselves to the sun by sitting on dry plants to reduce rapid water loss and can remain in this sitting position for months without food or water. The juveniles only move when they are in serious danger. They sit with their legs held tightly to the body and feet hidden under their skin folds. During this period, since there is no food or water intake, the juvenile frog does not urinate or defecate. The body stores all nitrogenous waste as urea in body fluids and purines. As the hot weather increases the dorsal skin of the frog becomes white due to the presence iridophores that can reflect light like a mirror since they are filled with purines crystals.
Insect physiology
Insect respiration is accomplished without lungs using a system of internal tubes and sacs through which gases either diffuse or are actively pumped, delivering oxygen directly to tissues that need oxygen and eliminate carbon dioxide via their cells. Since oxygen is delivered directly, the circulatory system is not used to carry oxygen, and is therefore greatly reduced; it has no closed vessels (i.e., no veins or arteries), consisting of little more than a single, perforated dorsal tube which pulses peristaltically, and in doing so helps circulate the hemolymph inside the body cavity.
Fish physiology
Fish from multiple groups can live out of the water for extended time periods. Amphibious fish such as the mudskipper can live and move about on land for up to several days, or live in stagnant or otherwise oxygen depleted water. Many such fish can breathe air via a variety of mechanisms. The skin of anguillid eels may absorb oxygen directly. The buccal cavity of the electric eel may breathe air. Catfish of the families Loricariidae, Callichthyidae, and Scoloplacidae absorb air through their digestive tracts. Lungfish, with the exception of the Australian lungfish, and bichirs have paired lungs similar to those of tetrapods and must surface to gulp fresh air through the mouth and pass spent air out through the gills. Gar and bowfin have a vascularized swim bladder that functions in the same way. Loaches, trahiras, and many catfish breathe by passing air through the gut. Mudskippers breathe by absorbing oxygen across the skin (similar to frogs). A number of fish have evolved so-called accessory breathing organs that extract oxygen from the air. Labyrinth fish (such as gouramis and bettas) have a labyrinth organ above the gills that performs this function. A few other fish have structures resembling labyrinth organs in form and function, most notably snakeheads, pikeheads, and the Clariidae catfish family.
Pacific tree frog
Skin color is produced via pigment cells called chromatophores. Three types of chromatophores are commonly found in amphibians: Xanthophores, which contain yellow, orange, or red pigments and are found uppermost on the dermis; iridophores, which lie below the xanthophores and function by reflecting and scattering white light up through them (in the case of "Pseudacris regilla" and many other North American frogs, iridophores reflect blue light through the yellow pigment cells above to create a green frog) and melanophores, which are the deepest pigment cells and are responsible for the presence of black and brown pigments.
Telmatobius culeus
While the lungs are greatly reduced, this frog has excessive amounts of skin, used to help the frog respire in the cold water in which it lives. The color is highly variable, but generally gray, brown or greenish above, and paler below.
Amphibian
Amphibian skin is permeable to water. Gas exchange can take place through the skin (cutaneous respiration) and this allows adult amphibians to respire without rising to the surface of water and to hibernate at the bottom of ponds. To compensate for their thin and delicate skin, amphibians have evolved mucous glands, principally on their heads, backs and tails. The secretions produced by these help keep the skin moist. In addition, most species of amphibian have granular glands that secrete distasteful or poisonous substances. Some amphibian toxins can be lethal to humans while others have little effect. The main poison-producing glands, the paratoids, produce the neurotoxin bufotoxin and are located behind the ears of toads, along the backs of frogs, behind the eyes of salamanders and on the upper surface of caecilians.
Ghost frog
Ghost frogs have morphological adaptation suited to surviving on the rocks around these streams. They are medium-sized frogs, reaching a length of , with flat bodies, enabling them to climb inside rocky crevices. They have very large toe discs in comparison to their size, which helps to cling onto rocks. The mouthparts of the tadpoles are modified into sucking discs, to allow them to cling to substrates, and remain still while they are feeding.
Frog
The eyes of most frogs are located on either side of the head near the top and project outwards as hemispherical bulges. They provide binocular vision over a field of 100° to the front and a total visual field of almost 360°. They may be the only part of an otherwise submerged frog to protrude from the water. Each eye has closable upper and lower lids and a nictitating membrane which provides further protection, especially when the frog is swimming. Members of the aquatic family Pipidae have the eyes located at the top of the head, a position better suited for detecting prey in the water above. The irises come in a range of colours and the pupils in a range of shapes. The common toad ("Bufo bufo") has golden irises and horizontal slit-like pupils, the red-eyed tree frog ("Agalychnis callidryas") has vertical slit pupils, the poison dart frog has dark irises, the fire-bellied toad ("Bombina spp.") has triangular pupils and the tomato frog ("Dyscophus spp.") has circular ones. The irises of the southern toad ("Anaxyrus terrestris") are patterned so as to blend in with the surrounding camouflaged skin.
Blanchard's cricket frog
Blanchard's cricket frogs have warty skin that is usually brown, gray, tan, or olive green, with darker bands of color on the legs. Their skin is also known to be extremely vascularized which can cause things to get through there bodies very fast and increase the effects of diseases they are exposed to. A dark, triangular mark between the eyes is frequently seen. They are small, growing to in length. They generally inhabit slow-moving or stagnant bodies of water, and are the most aquatic of tree frogs in North America. They hibernate during the cold months, emerging in late March or early April and beginning hibernation in late October. Breeding occurs from mid-May to mid-July, and females lay small clusters or single eggs. Tadpoles emerge in late summer. Breeding males have a metallic clicking call distinctive to the species. The subspecies is named after Frank N. Blanchard, a noted American herpetologist. Most commonly found in streams and wetlands for reproduction. Only a few last until the second breading season, if a breeding season isn't productive it can lead to a decrease in population for that area.
Blanchard's cricket frogs can be found through most of the Midwest United States, ranging from Michigan and Wisconsin in the north to southern Texas in the south and from Colorado in the west to West Virginia in the east. Although not listed at the federal level, Blanchard's cricket frogs are considered at risk in some states. It is an endangered species in Wisconsin, and is a threatened species in Michigan, due to a significant population decline since the late 1970's. Habitat loss, chemical contaminants, and competition for resources have been posited as reasons for this decline. Populations can still be found in the southern and western portions of Michigan's Lower Peninsula. "A. crepitans", including "A. c. blanchardi", is also considered endangered in Minnesota. It may also still be on Pelee Island, Ontario, Canada, but has not been reported since 1987. It was thought that competition among Bullfrogs caused a decrease in the population of Blanchard's cricket frog, however, after a study was conducted there was no evidence of this. In this study Bullfrog tadpoles were put together with Blanchard's cricket frog tadpoles, over the course of the study no evidence suggested that the Bullfrogs were taking enough resources to impact the cricket frogs.This eliminated the Bullfrog as a possible reason on why Blanchard's cricket frogs have decreased in certain areas where both species are present. In another study done about the immune defense traits of Blanchard's cricket frog found information about the reason for decline. This study showed that multiple factors can influence the immune system of the frog, for example water conductivity, water surface area, and ratio of natural to managed land. All of these factors were found to influence the skin microbiome of the frog, which will cause the immune system of the frog to decrease. While some decreases in population are due to chemical contaminants and competition for resources, the major reason for the decrease is still unknown.
Reptile
All reptiles breathe using lungs. Aquatic turtles have developed more permeable skin, and some species have modified their cloaca to increase the area for gas exchange. 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. This is also the same musculature that is used during locomotion. Because of this constraint, most squamates are forced to hold their breath during intense runs. Some, however, have found a way around it. Varanids, and a few other lizard species, employ buccal pumping as a complement to their normal "axial 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.
Agalychnis lemur
Chytrid fungus has been plaguing amphibians globally resulting in a number of amphibian extinctions. Researchers are currently using non-invasive imaging technology to better understand how a specific species of tree frogs in Central America are proving resilience to this fungus. Scientist are attributing tree frog's ability to withstand the deadly fungus to their unusual skin which allows the frogs to bask in the hot sunlight boosting their temperatures adequately enough to kill off the fungus. While typically a frog's long exposure to sunlight would dry out its skin, this species of tree frogs in Costa Rica thrive under the high temperature conditions. Scientists believe these tree frogs are able to thrive under these harsh conditions, which normally negatively affect frogs because of their skins ability to reflect the sunlight, regulating their core temperature, yet maintaining enough heat to kill off the chytrid fungus. It should also be noted that the antimicrobial skin peptides in the skin of "Agalychnis lemur" have shown to be a strong preventative measure for chytrid fungus, in particular Batrachochytrium dendrobatidis.
Batrachotoxin
The frogs do not produce batrachotoxin themselves. Just as in the birds, it is believed that these frogs gain the toxin from batrachotoxin-containing insects that they eat, and then secrete it through the skin. Beetles in the genus Choresine are not found in Colombia, but it is thought that the frogs might get the toxin from beetles in other genera within the family Melyridae, which could be found in Colombia.
Swikee
The taste and texture of frog meat is approximately between chicken and fish. They are often said to taste like chicken because of their mild flavor, with a texture most similar to chicken wings. However, some may perceive a slight fishiness. Normally, the legs are the only part served in the soup, since the legs are the most meaty parts; the skin of the frogs may, however, also be dried under the sun, and fried as chips. The salted fried frogs skin has a unique taste incomparable with other types of chips.
Frog
Tree frogs live high in the canopy, where they scramble around on the branches, twigs, and leaves, sometimes never coming down to earth. The "true" tree frogs belong to the family Hylidae, but members of other frog families have independently adopted an arboreal habit, a case of convergent evolution. These include the glass frogs (Centrolenidae), the bush frogs (Hyperoliidae), some of the narrow-mouthed frogs (Microhylidae), and the shrub frogs (Rhacophoridae). Most tree frogs are under in length, with long legs and long toes with adhesive pads on the tips. The surface of the toe pads is formed from a closely packed layer of flat-topped, hexagonal epidermal cells separated by grooves into which glands secrete mucus. These toe pads, moistened by the mucus, provide the grip on any wet or dry surface, including glass. The forces involved include boundary friction of the toe pad epidermis on the surface and also surface tension and viscosity. Tree frogs are very acrobatic and can catch insects while hanging by one toe from a twig or clutching onto the blade of a windswept reed. Some members of the subfamily Phyllomedusinae have opposable toes on their feet. The reticulated leaf frog ("Phyllomedusa ayeaye") has a single opposed digit on each fore foot and two opposed digits on its hind feet. This allows it to grasp the stems of bushes as it clambers around in its riverside habitat.
Allopumiliotoxin
As stated previously, these alkaloids were first discovered in the skins of frogs. They can be isolated from the frog’s skin by mincing the skin and extracting the compounds by trituration. A series of extractions involving an acid-base extraction are needed to isolate the allopumiliotoxins. The skins of the frogs may contain a number of different allopumiliotoxins. For example, the skin of Dendrobates tricolor was found to contain alkalkoids 251D, 271, 341A, and 323B. Also, different frogs contain different alkaloids in their skin. Dendrobates auratus, for example, was found to contain (+)-allopumiliotoxin 339A (a compound not present in the skin of Dendrobates tricolor).
Pipidae
These frogs are exclusively aquatic and have numerous morphological modifications befitting their habitat. For example, the feet are completely webbed, the body is flattened, and a lateral line system is present. In addition, pipids possess highly modified ears for producing and receiving sound underwater. They lack a tongue or vocal cords, instead having bony rods in the larynx that help produce sound. They range from in body length.
Amphibian
Amphibians are ectothermic (cold-blooded) vertebrates that do not maintain their body temperature through internal physiological processes. Their metabolic rate is low and as a result, their food and energy requirements are limited. In the adult state, they have tear ducts and movable eyelids, and most species have ears that can detect airborne or ground vibrations. They have muscular tongues, which in many species can be protruded. Modern amphibians have fully ossified vertebrae with articular processes. Their ribs are usually short and may be fused to the vertebrae. Their skulls are mostly broad and short, and are often incompletely ossified. Their skin contains little keratin and lacks scales, apart from a few fish-like scales in certain caecilians. The skin contains many mucous glands and in some species, poison glands (a type of granular gland). The hearts of amphibians have three chambers, two atria and one ventricle. They have a urinary bladder and nitrogenous waste products are excreted primarily as urea. Most amphibians lay their eggs in water and have aquatic larvae that undergo metamorphosis to become terrestrial adults. Amphibians breathe by means of a pump action in which air is first drawn into the buccopharyngeal region through the nostrils. These are then closed and the air is forced into the lungs by contraction of the throat. They supplement this with gas exchange through the skin.
Frog
The structure of the feet and legs varies greatly among frog species, depending in part on whether they live primarily on the ground, in water, in trees or in burrows. Frogs must be able to move quickly through their environment to catch prey and escape predators, and numerous adaptations help them to do so. Most frogs are either proficient at jumping or are descended from ancestors that were, with much of the musculoskeletal morphology modified for this purpose. The tibia, fibula, and tarsals have been fused into a single, strong bone, as have the radius and ulna in the fore limbs (which must absorb the impact on landing). The metatarsals have become elongated to add to the leg length and allow frogs to push against the ground for a longer period on take-off. The illium has elongated and formed a mobile joint with the sacrum which, in specialist jumpers such as ranids and hylids, functions as an additional limb joint to further power the leaps. The tail vertebrae have fused into a urostyle which is retracted inside the pelvis. This enables the force to be transferred from the legs to the body during a leap.
Cryobiology
For the wood frog ("Rana sylvatica"), in the winter, as much as 45% of its body may freeze and turn to ice. "Ice crystals form beneath the skin and become interspersed among the body's skeletal muscles. During the freeze, the frog's breathing, blood flow, and heartbeat cease. Freezing is made possible by specialized proteins and glucose, which prevent intracellular freezing and dehydration." The wood frog can survive up to 11 days frozen at -4 °C.
African clawed frog
"X. laevis" have been known to survive 15 or more years in the wild and 25–30 years in captivity. They shed their skin every season, and eat their own shed skin.
Karen Lips
Following her PhD, Lips became an Assistant Professor at St. Lawrence University between 1995 and 1998. In that position, she returned to Costa Rica in 1996 and observed the overall abundance of frogs in the region was down 90%. Her observations echoed those documented at a number of other ecological sites where amphibians were mysteriously dying off over the previous 15 years. While some of the population decline could be attributed to habitat destruction, the areas Lips was researching were untouched and relatively unexplored environments. She moved her field research site to Fortuna, Costa Rica where she and her colleagues, including Rick Speare, found dead and dying frogs. They collected 50 dead frogs to send back to a veterinary pathologist in Maryland, who discovered that a protozoan of some sort had infiltrated their skin. With a team of collaborators, the protozoan was eventually identified as "Batrachochytrium dendrobatidis", or "Bd", which belongs to a phylum of fungus called chytrids. Amphibians drink and breathe by absorbing water and oxygen through their skin, but chytrids grow all over their bodies and interfere with their blood chemistry, leading to organ failure and eventual death. Since "Bd" was identified, it's been implicated in the collapse or extinction of over 200 amphibian species.
Frog
Frogs have three-chambered hearts, a feature they share with lizards. Oxygenated blood from the lungs and de-oxygenated blood from the respiring tissues enter the heart through separate atria. When these chambers contract, the two blood streams pass into a common ventricle before being pumped via a spiral valve to the appropriate vessel, the aorta for oxygenated blood and pulmonary artery for deoxygenated blood. The ventricle is partially divided into narrow cavities which minimizes the mixing of the two types of blood. These features enable frogs to have a higher metabolic rate and be more active than would otherwise be possible.