Snake - Wikipedia. Snakes are elongated, legless, carnivorousreptiles of the suborder. Snake skeletons are not very complex because they do not have any appendages (limbs). A few species, such as boas and pythons, retain some vestigial structures. Serpentes. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads with their highly mobile jaws. To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have evolved elongate bodies without limbs or with greatly reduced limbs about twenty five times indepenently via convergent evolution, leading to many lineages of legless lizards and snakes. More than 2. 0 families are currently recognized, comprising about 5. The oldest preserved descriptions of snakes can be found in the Brooklyn Papyrus. Most species are nonvenomous and those that have venom use it primarily to kill and subdue prey rather than for self- defense. Some possess venom potent enough to cause painful injury or death to humans. Nonvenomous snakes either swallow prey alive or kill by constriction. Etymology. The English word snake comes from Old Englishsnaca, itself from Proto- Germanic*snak- an- (cf. Germanic. Schnake . ![]() ![]() Fossils readily identifiable as snakes (though often retaining hind limbs) first appear in the fossil record during the Cretaceous period. This is caused by the evolution of Hox genes, controlling limb morphogenesis. The axial skeleton of the snakes’ common ancestor, like most other tetrapods, had regional specializations consisting of cervical (neck), thoracic (chest), lumbar (lower back), sacral (pelvic), and caudal (tail) vertebrae. Early in snake evolution, the Hox gene expression in the axial skeleton responsible for the development of the thorax became dominant. As a result, the vertebrae anterior to the hindlimb buds (when present) all have the same thoracic- like identity (except from the atlas, axis, and 1–3 neck vertebrae). In other words, most of a snake's skeleton is an extremely extended thorax. Ribs are found exclusively on the thoracic vertebrae. Neck, lumbar and pelvic vertebrae are very reduced in number (only 2–1. However, the tail is still long enough to be of important use in many species, and is modified in some aquatic and tree- dwelling species.
Many modern snake groups originated during the Paleocene, alongside the adaptive radiation of mammals following the extinction of (non- avian) dinosaurs. The expansion of grasslands in North America also led to an explosive radiation among snakes. These include fossil species like Haasiophis, Pachyrhachis and Eupodophis, which are slightly older than Najash. It has many snake- like features, is adapted for burrowing and its stomach indicates that it was preying on other animals. Tetrapodophis does not have distinctive snake features in its spine and skull. ![]() This ultimately led to an animal similar to today's sea snakes. In the Late Cretaceous, snakes recolonized land, and continued to diversify into today's snakes. Fossilized snake remains are known from early Late Cretaceous marine sediments, which is consistent with this hypothesis; particularly so, as they are older than the terrestrial Najash rionegrina. The Western hognose snake is a harmless, diurnal North American colubrid that has grown in popularity in collections around the globe. Its natural range extends from. How common are snake bites? There are millions of venomous snake bites each year around the world, resulting in more than 100,000 deaths. The majority of fatalities. Interesting Green vine snake (Oxybelis fulgidus) Facts: Green vine snake can reach 59 to 79 inches in length. Body has only 0.79 inches in diameter. Similar skull structure, reduced or absent limbs, and other anatomical features found in both mosasaurs and snakes lead to a positive cladistical correlation, although some of these features are shared with varanids. However, more evidence links mosasaurs to snakes than to varanids. Fragmented remains found from the Jurassic and Early Cretaceous indicate deeper fossil records for these groups, which may potentially refute either hypothesis. More advanced snakes have no remnants of limbs, but basal snakes such as pythons and boas do have traces of highly reduced, vestigial hind limbs. Python embryos even have fully developed hind limb buds, but their later development is stopped by the DNA mutations in the ZRS. Alethinophidia is sometimes split into Henophidia and Caenophidia, with the latter consisting of . For instance, many sources classify Boidae and Pythonidae as one family, while some keep the Elapidae and Hydrophiidae (sea snakes) separate for practical reasons despite their extremely close relation. Recent molecular studies support the monophyly of the clades of modern snakes, scolecophidians, typhlopids + anomalepidids, alethinophidians, core alethinophidians, uropeltids (Cylindrophis, Anomochilus, uropeltines), macrostomatans, booids, boids, pythonids and caenophidians. Also found in southern China (Fujian, Hong Kong and on Hainan Island) and in Laos. ![]() Elapidae. Boie, 1. Elapids. On land, worldwide in tropical and subtropical regions, except in Europe. Sea snakes occur in the Indian Ocean and the Pacific. Disjunct populations in northeastern and southeastern South America. Gerrhopilidae. Vidal, Wynn, Donnellan and Hedges 2. Indo- Malayan blindsnakes. Southern & southeastern Asia, including Sri Lanka, the Philippines, and New Guinea. Leptotyphlopidae. Stejneger, 1. 89. Slender blind snakes. Africa, western Asia from Turkey to northwestern India, on Socotra Island, from the southwestern United States south through Mexico and Central to South America, though not in the high Andes. In Pacific South America they occur as far south as southern coastal Peru, and on the Atlantic side as far as Uruguay and Argentina. In the Caribbean they are found on the Bahamas, Hispaniola and the Lesser Antilles. Typhlopidae. Merrem, 1. Typical blind snakes. Most tropical and many subtropical regions around the world, particularly in Africa, Madagascar, Asia, islands in the Pacific, tropical America and in southeastern Europe. Xenotyphlopidae. Vidal, Vences, Branch and Hedges 2. Round- nosed blindsnake. Northern Madagascar. Legless lizards. While snakes are limbless reptiles, which evolved from (and are grouped with) lizards, there are many other species of lizards which have lost their limbs independently and superficially look similar to snakes. These include the slow worm and glass snake. Biology. Size. The now extinct. Titanoboa cerrejonensis snakes found were 1. In pit vipers, the grooves are located between the nostril and the eye in a large . Other infrared- sensitive snakes have multiple, smaller labial pits lining the upper lip, just below the nostrils. They smell by using their forked tongues to collect airborne particles, then passing them to the vomeronasal organ or Jacobson's organ in the mouth for examination. In water- dwelling snakes, such as the anaconda, the tongue functions efficiently underwater. This allows snakes to be able to sense approaching animals by detecting faint vibrations in the ground. Some snakes, such as the Asian vine snake (genus Ahaetulla), have binocular vision, with both eyes capable of focusing on the same point. Most snakes focus by moving the lens back and forth in relation to the retina, while in the other amniote groups, the lens is stretched. Many nocturnal snakes have slit pupils while diurnal snakes have round pupils. Skin. The skin of a snake is covered in scales. Contrary to the popular notion of snakes being slimy because of possible confusion of snakes with worms, snakeskin has a smooth, dry texture. Most snakes use specialized belly scales to travel, gripping surfaces. The body scales may be smooth, keeled, or granular. The eyelids of a snake are transparent . In the case of snakes, the complete outer layer of skin is shed in one layer. Scales are named mainly according to their positions on the body. Their eyes are always open, and for sleeping, the retina can be closed or the face buried among the folds of the body. Molting. A snake shedding its skin. Molting, or ecdysis, serves a number of functions. Firstly, the old and worn skin is replaced; secondly, it helps get rid of parasites such as mites and ticks. Renewal of the skin by moulting is supposed to allow growth in some animals such as insects; however, this has been disputed in the case of snakes. Before a molt, the snake stops eating and often hides or moves to a safe place. Just before shedding, the skin becomes dull and dry looking and the eyes become cloudy or blue- colored. The inner surface of the old skin liquefies. This causes the old skin to separate from the new skin beneath it. After a few days, the eyes clear and the snake . The old skin breaks near the mouth and the snake wriggles out, aided by rubbing against rough surfaces. In many cases, the cast skin peels backward over the body from head to tail in one piece, like pulling a sock off inside- out. A new, larger, brighter layer of skin has formed underneath. But a younger snake, still growing, may shed up to four times a year. This periodic renewal has led to the snake being a symbol of healing and medicine, as pictured in the Rod of Asclepius. A probe is inserted into the cloaca until it can go no further. The probe is marked at the point where it stops, removed, and compared to the subcaudal depth by laying it alongside the scales. The left and right sides of the lower jaw are joined only by a flexible ligament at the anterior tips, allowing them to separate widely, while the posterior end of the lower jaw bones articulate with a quadrate bone, allowing further mobility. The bones of the mandible and quadrate bones can also pick up ground borne vibrations. The jaw- quadrate- stapes pathway is capable of detecting vibrations on the angstrom scale, despite the absence of an outer ear and the ossicle mechanism of impedance matching used in other vertebrates to receive vibrations from the air. Tail vertebrae are comparatively few in number (often less than 2. The vertebrae have projections that allow for strong muscle attachment enabling locomotion without limbs. Autotomy of the tail, a feature found in some lizards is absent in most snakes. Western Hognose Snake Care Sheet. By Jeff Clayton. This is a “pink pastel” western hognose snake. Photo Credit: fivespots/Shutterstock. Western Hognose Snake (Heterodon nasiscus nasiscus; aka Plains hognose snake). The Western hognose snake is a harmless, diurnal North American colubrid that has grown in popularity in collections around the globe. Its natural range extends from southern Canada through the central U. S., including Arizona, New Mexico and Texas, into northern Mexico. This is a “peach” specimen. Dorsally, the Western hognose has a ground color of tan, brown, gray or olive, with darker, somewhat square blotches or bars, or rows of parallel spots that run longitudinally along the body. Ventrally, the Western hognose has glossy black scales, often interspersed with white, yellow or orange. Added to this is the Western hognose’s ability to compress, or flatten, its body when threatened (this might be an attempt on the snake’s part to appear larger and more dangerous to would- be predators). Often while in hissing mode, a Western hognose will also flatten out the ribs along its neck, or “hood” like a cobra. This bluff is most impressive with mature animals; in younger snakes it’s quite amusing. When a Western hognose does strike, it hits the predator with its heavily keeled snout, but does not bite. The snake rolls over onto its back, with mouth agape and lolling tongue. When flipped upright by hand, it will resume its death feign by rolling back onto its back, which can be quite amusing to witness. This death act is also sometimes accompanied with the Western hognose squirting a foul- smelling musk from anal glands located on either side of the cloaca (not as amusing to witness). I have worked with the Western hognose for many years, and it is my absolute favorite snake to keep and work with. Males are somewhat smaller, averaging between 1. A plastic, 5- gallon terrarium with a secure lid is ideal for a hatchling. These are inexpensive and widely available at most pet stores that sell reptile supplies. An adult Western hognose can be kept in a 2. The Western hognose is a ground- dwelling species, so opt for an enclosure with a greater amount of floor space; height is not as important. I normally use three different sizes: 5- liter boxes for established hatchlings, 3. Shoe and sweater boxes should have ample ventilation, especially in more humid regions, which can be achieved by drilling holes into them. While it is not the most aesthetically pleasing, it is inexpensive, inhibits the growth of bacteria and eliminates the threat of a hatchling ingesting substrate that could cause an abdominal impaction. It is easy to clean, allows the snakes to burrow, and, unlike cedar and pine, it is not hazardous to a snake’s respiratory system. Also popular, and generally safe, are recycled newspaper products that make cleaning up after the snakes easy. They also absorb odors fairly well and allow the snakes to burrow, which is important to hognoses, especially younger snakes. Some keepers prefer to feed their snakes in a separate enclosure or receptacle to prevent their possibly ingesting substrate. There are a range of full- spectrum lighting products available at local pet retail outlets that will fulfill the requirements of your Western hognose. One of these can be used to provide a hot spot basking area maintained at about 9. Fahrenheit for your Western hognose. Be sure to get an appropriately sized heater to allow for a heat gradient—you don’t want it to heat more than one- third of the enclosure, so the snake can get away from the heat if desired—and never use medical heat pads found in pharmacies. While these may be adjustable, they can be potential fire hazards, or overheat the enclosure. Hot rocks are also to be avoided. The cooler end of the enclosure can be maintained in the high 7. In a rack set- up, heat tape and a programmable thermostat or rheostat combination is most commonly used to provide heat. These can be purchased from reptile specialty stores or online. Heat tape is normally affixed to the shelving the enclosure sits on or in, and is a very good and easily manageable method for heating the enclosures in a rack. For these reasons, it’s best to use tongs, forceps or hemostats when feeding Western hognoses. Once it has been swallowed it should produce a noticeable lump, but not one that is so large that it is still noticeable 2. In the wild, Western hognoses consume a variety of prey items, including small rodents, lizards, amphibians and the eggs of ground- nesting animals. Pets do very well on a diet of pre- killed or frozen/thawed mice. Many Western hognose keepers prefer frozen/thawed rodents because they are easier for the snake to digest; at the cellular level, the food item has been broken down by about half. Also, as with pre- killed mice, the risk of your Western hognose being injured by a live mouse is eliminated. Responsible breeders will not offer Western hognoses for sale unless they are established feeders. It is best to feed babies with small hemostats so you can better manipulate the prey item, and use it to draw the attention of the baby hognose. Most babies will readily accept as their first meal a thawed pinky mouse dipped in warm water (and it’s interesting to watch a young hognose drink the water dripping off the mouse just before it begins eating it). Repeating this a few times during the first several meals will result in a young Western hognose becoming an established feeder that looks forward to mealtime. Scenting a thawed pinky mouse with canned tuna or salmon juice is easy and may encourage these snakes to eat. It usually gets good results, and it’s easy to wean the snakes off this form of scenting in a very short time. Sometimes “braining” a pinky works well, too, although this is not for the squeamish. It involves making a small pinhole in the skull of a frozen/thawed pinky, and squeezing a bit of brain matter out to smear on the mouse’s nose. Using toads can introduce dangerous parasites to the snake, and it can also be difficult to wean small Western hognoses off toad- scented mice. Finding toads throughout the year can present problems, too. Change the water and wash the water bowl at least every week, and more often if the snake fouls the water. While individuals may exhibit spectacular bluffing displays as mentioned previously, these are not signs of aggression. Do not bother a snake that is exhibiting bluffing behavior, so as not to cause it undue stress. Wait until the snake has calmed down, and then handle it. Some snakes will gently take food off hemostats, or they may prefer having food left in a quiet corner of the enclosure to eat at their leisure. Others will emerge from their enclosures ready for food with mouths open. No matter which type of behavior your animal displays, use hemostats, tongs or forceps to reduce the chance of an accidental bite. If a bite occurs, do not force the snake off by yanking on it, which could damage its jaws. Instead, pour a small capful of mint mouthwash onto the area the snake is biting. This is harmless to the snake and will result in it releasing its bite. Sometimes a hognose bite may lead to mild swelling at and around the bite site. This is best remedied by cleaning the location of the bite with soap and water and taking Benedryl within an hour after a bite occurs. It produces a proto- lipase enzyme cocktail in its saliva (as nearly all life forms do) that many herpetological authorities believe is used to help break down food. When someone uses the term “venomous,” they are referring not only to the type of enzyme cocktail injected into a victim, but also the system used in the delivery of venom. The Western hognose has a very primitive and inefficient delivery system, and its oral secretions (saliva) are harmless to humans. One might also look at its enlarged maxillary teeth as being used primarily to secure and hold food items. Jeff Clayton has produced and worked with a large variety of Western hognose morphs. His current projects include a variety of color- phased Western hognoses, Lavender and pattern mutations. Visit his website at cahabariverreptiles.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
November 2017
Categories |