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Where are reptiles on the food chain? Do reptiles have a heart? How does the heart of crocodiles differ from that of other reptiles? What kind of food do reptiles eat?
Is it illegal to keep wild reptiles? How many chambers are there in the heart of amphibians and reptiles and what are the disadvantages of they have chambered heart? Does snakes kind of reptiles? Do reptiles have a more complex heart than amphibians? Do reptiles have a more complex heart that amphibians?
What is the relationship between the kind of eggs reptiles produce and where reptiles live? Does a reptile have a 2 chamber heart? What kind of animal is a iguanas?
What two reptiles have a four chambered heart? Trending Questions. Give me food and I will live give me water and I will die what am I? What is bigger than an asteroid but smaller than Mercury and farther from the sun than Neptune? Still have questions? Find more answers. It is assumed that reptiles cannot produce enough energy required for long-distance chase like the warm-blooded animals.
However, it remains unclear as to whether their cold-bloodedness is as a result of their ecology or not. Reptiles have either four legs, or some like snakes, are descendants of four-limbed ancestors. In most snakes, all traces of legs including bones for the legs have disappeared.
However, they still remain successful predators even without the legs. Snakes have three ways of moving on land; straight crawling, lateral undulating, and sidewinding. Although lizards have four limbs, most lizards have an alternating gait which limits their endurance. The tail of some lizards is prehensile and can assist them in climbing. Some reptiles like crocodiles have claws on their feet. These claws assist in movement and hunting. Reptiles breathe through their lungs.
Although turtles have permeable skin through which gaseous exchange takes place while some species increase the rate of gaseous exchange through the cloaca, the breathing process can only be completed through the lungs.
Breathing through the lung is accomplished differently in different groups of reptiles. In lizards and snakes, the lungs are ventilated by axial musculature which is also used in locomotion. Because of these, most of the species are forced to hold their breath during intense activities. The embryo is surrounded by fluid held with the amnion. The fluid provides the embryo with the aquatic environment it obviously still requires but which in amphibians is supplied by the waters of a pond or stream.
Another sac, called the allantois, projects from the embryo's lower digestive tract the hind gut and acts as a bladder to receive the embryo's waste products. The allantois sac becomes quite large, expanding out until its wall joins that of the chorion to form the chorioallantoic membrane, which is pressed up against the inside of the shell.
Not only does the allantois serve as a bladder, receiving and storing insoluble wastes, but it also acts as a sort of "lung," allowing oxygen and carbon dioxide to pass to and from the embryo through the slightly porous permeable egg shell. Internal Fertilization Because the egg cell reaches the outside environment surrounded by the shell of the egg, it is necessary that it be fertilized before it leaves the female's body; thus, in all reptiles fertilization is internal, with males depositing sperm within the females'genital tracts.
In snakes and lizards the male organ, called the hemipenes, is actually a pair of structures, with one of the pair, or hemipenis, situated internally on each side of the male's vent. Each hemipenis, which itself may be forked, is a functional structure: either one may be protruded from the vent and used in mating, the choice usually depending upon the placement of the male's mate.
In turtles and crocodilians there is a single penis, which serves only for the transmission of sperm and not also for the elimination of excretory products, as in mammals.
In the lizardlike tuatara, Sphenodon , the only living species in its order, the male lacks a copulatory organ, and mating is accomplished by the pressing together of the male's and female's cloacae, as in most birds.
The Heart Except for crocodilians, which have a four-chambered heart, all reptiles have a three-chambered heart consisting of two atria and one ventricle. The chamber called the right atrium receives deoxygenated, or "spent," blood returning from the body tissues.
It passes this blood into the ventricle, from where it is pumped to the lungs for oxygenation. The oxygenated blood from the lungs returns to the left atrium and once again enters the same ventricle, from which it is pumped to the body tissues. Even in the three-chambered heart, however, as recent research has shown in contrast to earlier beliefs, there is little mixing of oxygenated and deoxygenated blood. This has been achieved by the development within the ventricle of interconnected "subchambers" within which a sequence of changes in blood pressure takes place.
Several anatomical variations occur among the reptiles, but a simplified description of the lizard heart will serve to illustrate one way in which this circulatory efficiency was accomplished. The ventricle of the lizard heart is incompletely partitioned into two subchambers by a muscular ridge that descends from the roof of the heart almost to the floor.
The right subchamber is called the right ventricle, or cavum pulmonale; it leads to the lungs. The left subchamber is called the left ventricle, or cavum venosum; it receives blood from the right atrium and leads to the body.
The two subchambers are connected not only beneath the partition but also across its incomplete rearward end. A third subchamber, called the cavum arteriosum, is situated in the upper wall of the right ventricle; it receives blood from the left atrium and is connected through a valve-controlled opening to the left ventricle.
When the two atria contract, oxygenated blood from the left atrium enters the third subchamber, or cavum arteriosum, pressing against and shutting the valves controlling the opening into the left ventricle; this closes off the third subchamber and temporarily holds its contained blood in storage.
At the same time the deoxygenated blood in the right atrium has been pumped into the left ventricle, filling it to overflowing, the excess blood moving across the open posterior end of the muscular partition into the right ventricle. The three ventricular subchambers are now filled with blood; oxygenated blood in the third subchamber cavum arteriosum and deoxygenated blood in the two ventricles.
Resistance to blood flow is lower in the pulmonary heart-lung circuit than in the systemic heart-body circuit, so that when the ventricles contract, the deoxygenated blood in the right ventricle follows the path of least resistance and proceeds through the pulmonary artery into the lungs. The emptying of the right ventricle causes more deoxygenated blood from the left ventricle to move around the open end of the partition into the right ventricle and to continue on to the lungs.
The contraction of the ventricle also brings the partitioning muscular ridge into full contact with the floor of the heart, sealing off any flow from the right ventricle back into the left ventricle.
As the ventricles continue their contraction, the pressure on the blood held within the third subchamber cavum arteriosum exerts a reverse force on the valves, opening the passageway between the third subchamber and the left ventricle. The oxygenated blood in the third subchamber now moves into the left ventricle and from there into the aortas leading to the body circulation. Metanephric Kidney Adult amphibians have an opisthonephric kidney, that is, one that was developed from the main mass except for the foremost end of kidney-forming tissue in the embryo; the collecting tubules of the amphibian's opisthonephric kidney are connected to a drainage tube called the archinephric, or Wolffian, duct.
In contrast, the metanephric kidney of adult reptiles and birds and mammals arises from the rearmost part of the kidney-forming tissue of the embryo — the front and middle portions having given rise to the pronephric and mesonephric kidneys, which eventually degenerate.
The collecting tubules of the metanephric kidney are connected to a "newly evolved" drainage tube, the ureter. The Wolffian duct, having lost its excretory function, becomes partly involved in the transmission of sperm in males but is a degenerate vestige in females.
In mammals the ureter drains into the bladder, which empties to the outside through another tube called the urethra. Crocodilians and snakes lack bladders, but even where one is present, as in most lizards and turtles, it is formed simply by an outpocketing of the cloaca and has no connection with the ureter.
The cloaca, whose name comes from the Latin word for sewer, is a body chamber leading to the outside and into which empty the excretory products of the kidneys, the waste products of the intestines, and the reproductive products of the testes and ovaries. The reptilian ureter empties into the cloaca, and if a bladder is present it receives and holds the urine overflow. Skull The reptilian skull ranges from the reduced, loosely joined, or kinetic, skull of snakes to the large, solid skull of crocodilians.
On each side of the skull behind the eye sockets there may be one or two openings formed at the junctions of certain bones.
The openings are believed to be an adaptation for more-efficient functioning of the jaw muscles, possibly by allowing them to bulge outward when the jaws are closed. Because the positions of the openings, as determined by the bones surrounding them, were considered critical in the classification of reptiles, skull types were designated by the row, or arch, of bones beneath each opening rather than by the openings themselves.
I have no idea how polymorphic these markers are, which may be more antigenic in reptiles, or which may be considered a basis for blood groupings! More information about various immune system parameters will come out of the anole genome project as people scrutinize the data, especially with respect to immune system evolution in vertebrates. Below is a link to some info about animal blood groups -. Both papers can be downloaded via Google.
Last edited by Steve Lolait 24th Jun
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