Amphibians & Reptiles

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Reptile Care
We are also giving her raw beef bones to supplement calcium and help keep her teeth clean, she loves them and her teeth are as clean as a puppy now! Surface tension transport of prey by feeding shorebirds: Rico-Guevara and Rubega found that hummingbird tongues do not function like a pair of tiny, static tubes drawing up floral nectar via capillary action. The legendary account of the foundation of Thebes mentioned a monster snake guarding the spring from which the new settlement was to draw its water. This did not affect reptiles as they were able to lay eggs on dry lands. Some of our favorite Bible verses Some species, such as the Sea Snakes and Sea Turtles, live in the ocean.

Reptiles - Amphibians Articles

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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. It was worshipped as one of the gods and was also used for sinister purposes: In Greek mythology snakes are associated with deadly antagonists, as a chthonic symbol, roughly translated as earthbound.

The nine-headed Lernaean Hydra that Hercules defeated and the three Gorgon sisters are children of Gaia , the earth. Medusa was one of the three Gorgon sisters who Perseus defeated. Medusa is described as a hideous mortal, with snakes instead of hair and the power to turn men to stone with her gaze.

After killing her, Perseus gave her head to Athena who fixed it to her shield called the Aegis. The Titans are depicted in art with their legs replaced by bodies of snakes for the same reason: They are children of Gaia, so they are bound to the earth. The cobra is seen on the neck of Shiva , while Vishnu is depicted often as sleeping on a seven-headed snake or within the coils of a serpent. There are temples in India solely for cobras sometimes called Nagraj King of Snakes , and it is believed that snakes are symbols of fertility.

In the annual Hindu festival of Nag Panchami , snakes are venerated and prayed to. The turtle has a prominent position as a symbol of steadfastness and tranquility in religion, mythology, and folklore from around the world. Deaths from snakebites are uncommon in many parts of the world, but are still counted in tens of thousands per year in India.

To produce antivenom, a mixture of the venoms of different species of snake is injected into the body of a horse in ever-increasing dosages until the horse is immunized. Blood is then extracted; the serum is separated, purified and freeze-dried. Geckos have also been used as medicine, especially in China. Crocodiles are protected in many parts of the world, and are farmed commercially. Their hides are tanned and used to make leather goods such as shoes and handbags ; crocodile meat is also considered a delicacy.

Farming has resulted in an increase in the saltwater crocodile population in Australia , as eggs are usually harvested from the wild, so landowners have an incentive to conserve their habitat. Crocodile leather is made into wallets, briefcases, purses, handbags, belts, hats, and shoes. Crocodile oil has been used for various purposes. In the Western world, some snakes especially docile species such as the ball python and corn snake are kept as pets. From Wikipedia, the free encyclopedia. Check the overall appearance of the reptiles: Check for changes in feeding habits: Look for changes in the appearance, consistency and amount of feces and urates: Check for any changes in behavior: Check for changes in shedding: Check for physical signs of illness an injury: If any of these signs occur, the environmental requirements of the species must be checked against the conditions actually occurring in the enclosure and any inadequacies or failures corrected.

If the proper physical environment is well established, the social environment needs to be looked at in enclosures where more than one animal is housed together. It should be noted that aggression and dominance behavior is not always overtly physical - there need not be any actual fighting.

Subtle behaviors on the part of the dominant animal may result in a subordinate animal staying away from basking areas and food, slowly dying of stress-enhanced hypothermia and starvation. If the physical and social environments inside the enclosure are not a problem, then the macroenvironment must be evaluated. Has the placement of the enclosure been changed to a different room or different part of the original room?

Have you moved your household? Had to evacuate due to a natural disaster? Had the in-laws over for the week, totally disrupting your usual animal maintenance and playtime schedule? Been gone on vacation?

These are all things that may seem like they wouldn't intrude on the life of our captive reptiles but, for many of them especially iguanas and other social lizards , most definitely do.

There are also the things that go on behind your back One woman found out from neighbor, who observed what was going on through the window while the owner was at work, that her cat would sit staring into her iguana's enclosure, nose pressed up against the glass, for hours at a time when the owner was at work. Since the cat never engaged in this behavior when the owner was home, she never thought there was a problem with the cat.

Another woman found out that her husband was turning off the heating equipment in her reptile's enclosure at night after she went to bed "to save money - it's a cold-blooded animal, so it doesn't need heat all the time" was his rationale when she finally figured out why her reptile was sick and stressed. So, just because you are not directly observing something going on doesn't mean that something isn't happening to result in fear and stress in your reptile.

You may need to become a sort of detective in carefully and deeply assessing everything that goes on in and around your reptile's enclosure as well as exploring as much as you can of the animal's natural history before you will be able to figure out what isn't right. Please note that if your conditions have not been set up appropriately before reading this material, the shedding, defecation, and growth patterns you have come to expect from your reptile may in fact be abnormal.

Reptile owners who have no previous experience with healthy reptiles believe that since their reptile is alive, eating, and defecating, that they are healthy.

One 4-H reptile program leader informed me, for example, that ball pythons never shed in one piece. Her snake was covered in patches of unshed skin representing different sheds, its eyes deeply dented from retained eye caps. Her snake was not healthy, but she insisted that, since that was the way her snake had always been, and that since it was alive and moving around, that it was "normal" for the species!

I frequently encounter iguana owners who tell me that their iguanas defecate only once or twice a week even though they are eating daily. This tells me right away that their temperatures are too low.

Once they are raised to the proper levels, the owners are often dismayed to find that, not only does the iguana increase its food intake, but its digestion speeds up to the proper rate, resulting in often copious defecation one or more times a day, depending upon the season. Most of these owners also find that their iguana isn't really as tame as they thought it was. Common Feeding Problems Failure of a reptile to feed may be due to one or more of several possible reasons.

To get the reptile to start eating, the underlying cause for the failure to feed must be identified and corrected: Simply forcing feeding an animal will not correct the problem situation; it will just give the animal energy to survive, not thrive.

Reasons for not eating include: If possible, it is always best to get the reptile to start self-feeding rather than resort to long-term forcing feeding or tube feeding.

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. This is useful for feeding on patchy, natural prey, but also on fishery wastes, which might be an important additional food resource for Wandering Albatrosses.

It is likely that this physiological characteristic evolved as a response to a diet largely composed of squid, and to a patchy distribution of this food resource resulting in large, infrequent meals. The strategy of Wandering Albatrosses is to cover long distances rapidly and at low costs to increase the probability of encountering dispersed prey patches whose distribution is unpredictable. Knots with large gizzards consumed far more molluscs with shells than the birds with smaller gizzards.

Birds with smaller gizzards simply couldn't feed fast enough. By allowing them to crush more shell per gizzard-full, larger gizzards gave birds the edge. Thus, even though it is energetically costly for the knots to maintain a larger gizzard, when the bird needs to get the most out of its crunchy diet, it's a price worth paying.

So, the birds' gizzards enlarge as they fatten for migration. Because the molluscs' shells stay the same size as the molluscs shrink, the amount of shell a bird must process to eat its fill also increases.

But with their larger gizzards, the birds can still make the most of even the crunchiest winter diet! Within 14 days, they showed a doubling of the size of their gizzards. Red Knots have strong muscular gizzards for feeding on molluscs.

A shift back to a mussel diet induced about a doubling in gizzard mass in just a few days. As the knots were fed progessively smaller mussels day 22 to day 46 that are easier to crush, gizzard mass again declined. A switch back to a soft food pellet diet caused a further decline in gizzard mass.

Finally, a switch back to a mussel diet again cause a rapid increase in gizzard mass From: Piersma and Drent Ostrich Struthio camelus stomach. Note how particle size of material in the gizzard ventriculus is smaller than in the proventriculus due to the grinding action of the muscular walls plus small pebbles gastroliths.

The capacity to reduce particle size is related to the metabolic demands of a species. Therefore, particle size reduction is often considered the key digestive difference between ecto- and endotherms that allows endotherms to rely on shorter digesta retention times without losing digestive efficiency, and hence facilitate the high level of food intake necessary to meet their increased metabolic requirements.

In contrast, adaptations for chewing intrinsically increase the weight of the head. The use of the gizzard system has the potential advantages that intake rate is not limited by chewing, that no investment in dental tissue is necessary, and that dental wear is not a determinant of senescence as observed in mammals. The absence of age-dependent tooth wear might even be a contributing factor to the slower onset of senescence in birds as compared to mammals.

On the other hand, the use of a gizzard requires the intake of suitable grit or stones—an action that represents, in the few studies where this has actually been quantified in birds, a relevant proportion of feeding time Fritz et al. Gastrointestinal tracts of a carnivorous hawk, an omnivorous chicken, and 4 herbivorous birds. Note larger size of crop in omnivore and herbivores, and particularly in hoatzin.

Ceca are small in hawks and relatively large in grouse. Although ceca are relatively small in Hoatzins , Emus, and Ostriches, an expanded foregut Hoatzins , a much longer midgut Emus , or a much longer colon Ostriches compensates for this From: Stevens and Hume Over-reliance on the passive pathway provides metabolic advantages and ecological constraints.

It does provide birds with an absorptive process that can deal with rapid and large changes in intestinal sugar concentrations.

The passive pathway is also energetically inexpensive to maintain and modulate. However, passive absorption through the paracellular pathway is dependent on concentration gradients. In the absence of a transport system that selects which materials to absorb, this non-discriminatory pathway may also increase vulnerability to toxins, and thus constrain foraging behavior and limit the breadth of the dietary niche of the birds.

Another problem is that when luminal sugar concentrations are lower than those in plasma, glucose may diffuse back into the lumen. Cross-section of the intestine ileum of a Spotted Tinamou Nothura maculosa. Villi are lined with columnar epithelium EP , including goblet cells arrows that secrete mucus.

The muscle layer includes longitudinal fibers MI on the perimeter, circular fibers Mc , and additional longitudinal fibers at the base of the villi muscularis muscosae; MM From: Chikilian and de Speroni Blue-headed Parrots at clay lick. Meyer-Rochow and Gal determined that the pressures involved could be approximated if they knew the 1 distance the feces traveled, 2 density and viscosity of the material, and 3 shape, aperture, and height of the anus above ground.

How penguins choose the direction of defecation, and how wind direction factors into that decision, remain unknown. Avian Pancreas tissue Source: The Avian Digestive Tract. Avian geophagy and soil characteristics in southeastern Peru.

Luminal morphology of the avian lower intestine: Histological aspects of the stomach proventriculus and gizzard of the Red-capped Cardinal Paroaria gularis gularis. Comparative study of the digestive system of three species of tinamou. Crypturellus tataupa, Nothoprocta cinerascens , and Nothura maculosa Aves: Journal of Morphology Journal of Experimental Zoology Rictal bristle function in Willow Flycatcher.

Dysplastic koilin causing proventricular obstruction in an Eclectus Parrot Eclectus roratus. Journal of Avian Medicine and Surgery Anatomy and physiology of the digestive system in fowl. Pages in Proc. An histological and histochemical analysis of the inner lining and glandular epithelium of the chicken gizzard.

American Journal of Anatomy An ecomorphological study of the raptorial digital tendon locking mechanism. Dietary and developmental regulation of intestinal sugar transport.

Digesta retention patterns in geese Anser anser and turkeys Meleagris gallopavo and deduced function of avian caeca. Comparative Biochemistry and Physiology A Histological and global gene expression analysis of the 'lactating' pigeon crop.

Vultures of the seas: Evolution of the structure and function of the vertebrate tongue. Journal of Anatomy Light and scanning electron microscopic study of the tongue in the cormorant Phalacrocorax carbo Phalacrocoracidae, Aves.

Functional morphology of the tongue in the nutcracker Nucifraga caryocatactes. A tropical horde of counterfeit predator eyes. Instructed learning in the auditory localization pathway of the Barn Owl. The morphology of the bill apparatus in the Steller's Sea Eagle. Wild Bird Society of Japan, Tokyo. Use of dung as a tool by burrowing owls. The integration of energy and nitrogen balance in the hummingbird Sephanoides sephaniodes. Does gut function limit hummingbird food intake?

Physiological and Biochemical Zoology Pressures produced when penguins pooh—calculations on avian defaecation. Scare tactics in a neotropical warbler: Gliding flight and soaring. Theoretical Ecology Series, vol. Modelling the flying bird C. Structure, form, and function of flight in engineering and the living world. Phenotypic flexibility and the evolution of organismal design. Trends in Ecology and Evolution The hummingbird tongue is a fluid trap, not a capillary tube. Between air and water: Use of prey hotspots by an avian predator: Structure and mechanical behavior of a toucan beak.

Movement and direction of movement of a simulated prey affect the success rate in Barn Owl Tyto alba attack.

Musculoskeletal underpinnings to differences in killing behavior between North American accipiters Falconiformes: Accipitridae and falcons Falconidae. Journal of Morphology, online early.

Le Bohec, and Y. Adjustments of gastric pH, motility and temperature during long-term preservation of stomach contents in free-ranging incubating King Penguins.

Journal of Experimental Biology A tough nut to crack. Adaptations to seed cracking in finches. Cost-benefit analysis of mollusc-eating in a shorebird. Optimizing gizzard size in the face of seasonal demands. How do woodpeckers extract grubs with their tongues? Why do woodpeckers resist head impact injury: Functional morphology of raptor hindlimbs: The turning- and linear-maneuvering performance of birds: Canadian Journal of Zoology Hummingbird jaw bends to aid insect capture.

A mechanical analysis of woodpecker drumming and its application to shock-absorbing systems. I - Introduction to Birds. VII - Circulatory System. Back to Avian Biology. Drawings of the digestive tracts of A a Greylag Goose and B a Wild Turkey and retention times of a solute, 2-mm particles, and 8-mm particles in the goose and turkey digestive systems Figure from Frei et al.

The closed, air-filled spaces reduce overall weight without loss of rigidity. The capillary ratchet mechanism Surface tension transport of prey by feeding shorebirds: The serrated leading-edge feather of an owl Norberg Vortex generators on an airplane wing.

Fish-eating species like cormorants below - typically have small, undifferentiated tongue because fish are often swallowed whole. Representative caterpillar false eyes and faces. In some, like woodpeckers, the 'sticky' saliva aids in capturing prey. In others, like swifts, saliva is used in nest building see photo below. The muscular walls of the esophagus produce wave-like contractions peristalsis that help propel food from the oral cavity to the stomach.

Anhinga swallowing a large fish. HCL and pepsinogen are secreted by the deep glands see photomicrograph below. Pepsinogen is converted into pepsin a proteolytic, or protein-digesting, enzyme by the HCl. The cuticle is secreted by simple tubular glands see photomicrograph below. Grinding action may, particularly in seed-eating birds, be assisted by grit and stones deliberately ingested.

The avian gastrointestinal tract, unlike that of mammals, executes distinct reverse peristaltic movements that are critical to optimal digestive function Duke The gastric reflux allows material in the gizzard to reenter the proventriculus for additional treatment with acid and pepsin. Villi are projections from the intestinal wall that increase the amount of surface area available for absorption. Further increasing the surface area are the numerous microvilli of the cells lining the surface of the villi.

Inside each villus are blood vessels that absorb nutrients for transport throughout the body. Caeca are histologically similar to the small and large intestines and found in a wide variety of birds. In these large ceca, food particles are acted upon by cecal secretions, bacteria, and fungi and nutrients can be absorbed. Lymphoid ceca are not important in digestion but contain lymphocytes white blood cells that produce antibodies Clench At various times and under various conditions, ceca are the site for 1 fermentation and further digestion of food especially for the breakdown of cellulose and absorption of nutrients, 2 production of antibodies, and 3 the use and absorption of water and nitrogenous components Clench The bursa is most prominent in young birds and serves as the area where B-lymphocytes the white blood cells that produce antibodies are generated T-lymphocytes are generated in the Thymus.

Bile emulsifies fats or, in other words, breaks fats down into tiny particles.

What Is a Reptile?