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Ular 

Sumber dari Wikipedia bahasa Indonesia, ensiklopedia bebas

Ular adalah reptil yang tak berkaki dan bertubuh panjang. Ular memiliki sisik seperti kadalSquamata). Perbedaannya adalah kadal pada umumnya berkaki, memiliki lubang telinga, dan kelopak mata yang dapat dibuka tutup. Akan tetapi untuk kasus-kasus kadal tak berkaki (misalnya Ophisaurus dan sama-sama digolongkan ke dalam reptil bersisik ( spp.) perbedaan ini menjadi kabur dan tidak dapat dijadikan pegangan.

Habitat dan Makanan

Ular merupakan salah satu reptil yang paling sukses berkembang di dunia. Di gunung, hutan, gurun, dataran rendah, lahan pertanian, lingkungan pemukiman, sampai ke lautan, dapat ditemukan ular. Hanya saja, sebagaimana umumnya hewan berdarah dingin, ular semakin jarang ditemui di tempat-tempat yang dingin, seperti di puncak-puncak gunung, di daerah Irlanda dan Selandia baru dan daerah daerah padang salju atau kutub.
Banyak jenis-jenis ular yang sepanjang hidupnya berkelana di pepohonan dan hampir tak pernah menginjak tanah. Banyak jenis yang lain hidup melata di atas permukaan tanah atau menyusup-nyusup di bawah serasah atau tumpukan bebatuan. Sementara sebagian yang lain hidup akuatik atau semi-akuatik di sungai-sungai, rawa, danau dan laut.
Ular memangsa berbagai jenis hewan lebih kecil dari tubuhnya. Ular-ular perairan memangsa ikan, kodok, berudu, dan bahkan telur ikan. Ular pohon dan ular darat memangsa burung, mamalia, kodok, jenis-jenis reptil yang lain, termasuk telur-telurnya. Ular-ular besar seperti ular sanca kembang dapat memangsa kambing, kijang, rusa dan bahkan manusia.

Kebiasaan dan Reproduksi

Ular memakan mangsanya bulat-bulat; artinya, tanpa dikunyah menjadi keping-keping yang lebih kecil. Gigi di mulut ular tidak memiliki fungsi untuk mengunyah, melainkan sekedar untuk memegang mangsanya agar tidak mudah terlepas. Agar lancar menelan, ular biasanya memilih menelan mangsa dengan kepalanya lebih dahulu.
Beberapa jenis ular, seperti sanca dan ular tikus, membunuh mangsa dengan cara melilitnya hingga tak bisa bernapas. Ular-ular berbisa membunuh mangsa dengan bisanya, yang dapat melumpuhkan sistem saraf pernapasan dan jantung (neurotoksin), atau yang dapat merusak peredaran darah (haemotoksin), dalam beberapa menit saja. Bisa yang disuntikkan melalui gigitan ular itu biasanya sekaligus mengandung enzim pencerna, yang memudahkan pencernaan makanan itu apabila telah ditelan.
Untuk menghangatkan tubuh dan juga untuk membantu kelancaran pencernaan, ular kerap kali perlu berjemur (basking) di bawah sinar matahari.
Kebanyakan jenis ular berkembang biak dengan bertelur. Jumlah telurnya bisa beberapa butir saja, hingga puluhan dan ratusan butir. Ular meletakkan telurnya di lubang-lubang tanah, gua, lubang kayu lapuk, atau di bawah timbunan daun-daun kering. Beberapa jenis ular diketahui menunggui telurnya hingga menetas; bahkan ular sanca ‘mengerami’ telur-telurnya.
Sebagian ular, seperti ular kadut belang, ular pucuk dan ular bangkai laut ‘melahirkan’ anak. Sebetulnya tidak melahirkan seperti halnya mamalia, melainkan telurnya berkembang dan menetas di dalam tubuh induknya (ovovivipar), lalu keluar sebagai ular kecil-kecil.
Sejenis ular primitif, yakni ular buta atau ular kawat Rhampotyphlops braminus, sejauh ini hanya diketahui yang betinanya. Ular yang mirip cacing kecil ini diduga mampu bertelur dan berbiak tanpa ular jantan (partenogenesis).

Macam-macam Ular

Ular ada yang berbisa (memiliki racun, venom/venomous), namun banyak pula yang tidak. Akan tetapi tidak perlu terlalu kuatir bila bertemu ular. Dari antara yang berbisa, kebanyakan bisanya tidak cukup berbahaya bagi manusia. Lagipula, umumnya ular pergi menghindar bila bertemu orang.
Ular-ular primitif, seperti ular kawat, ular karung, ular kepala dua, dan ular sanca, tidak berbisa. Ular-ular yang berbisa kebanyakan termasuk suku Colubridae; akan tetapi bisanya umumnya lemah saja. Ular-ular yang berbisa kuat di Indonesia biasanya termasuk ke dalam salah satu suku ular berikut: Elapidae (ular sendok, ular belang, ular cabai, dll.), Hydrophiidae (ular-ular laut), dan Viperidae (ular tanah, ular bangkai laut, ular bandotan).

Beberapa jenisnya, sebagai contoh:

Ular kisik alias ular lare angon, Xenochrophis vittatus
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Snake
From Wikipedia, the free encyclopedia

Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with many 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.
Living snakes are found on every continent except Antarctica and on most islands. Fifteen families are currently recognized, comprising 456 genera and over 2,900 species They range in size from the tiny, 10 cm-long thread snake to pythons and anacondas of up to 7.6 metres (25 ft) in length. The recently discovered fossil Titanoboa was 15 metres (49 ft) long. Snakes are thought to have evolved from either burrowing or aquatic lizards during the Cretaceous period (c 150 Ma). The diversity of modern snakes appeared during the Paleocene period (c 66 to 56 Ma).
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 English snaca, itself from Proto-Germanic *snak-an- (cf. German Schnake "ring snake," Swedish snok "grass snake"), from Proto-Indo-European root *(s)nēg-o- "to crawl, creep," which also gave sneak as well as Sanskrit nāgá "snake." The word ousted adder, as adder went on to narrow in meaning, though in Old English næddre was the general word for snake.The other term, serpent, is from French, ultimately from Indo-European *serp- (to creep), which also gave Greek érpo (ερπω) "I crawl."


Evolutio

  The fossil record of snakes is relatively poor because snake skeletons are typically small and fragile, making fossilization uncommon. However, 150 million-year-old specimens, readily identifiable as snakes, yet with lizard-like skeletal structures, have been uncovered in South America and Africa. There is consensus, on the basis of comparative anatomy, that snakes descended from lizards. Fossil evidence suggests that snakes may have evolved from burrowing lizards, such as the varanids or a similar group during the Cretaceous Period. An early fossil snake, Najash rionegrina, was a two-legged burrowing animal with a sacrum, and was fully terrestrial. One extant analog of these putative ancestors is the earless monitor Lanthanotus of Borneo, although it also is semiaquatic. Subterranean forms evolved bodies that were streamlined for burrowing and lost their limbs. According to this hypothesis, features such as the transparent, fused eyelids (brille) and loss of external ears evolved to cope with fossorial difficulies, such as scratched corneas and dirt in the ears. Some primitive snakes are known to have possessed hindlimbs, but their pelvic bones lacked a direct connection to the vertebrae. These include fossil species like Haasiophis, Pachyrhachis and Eupodophis, which are slightly older than Najash.
Primitive groups among the modern snakes, pythons and boas, have vestigial hind limbs; tiny, clawed digits known as anal spurs, which they use to grasp during mating. Leptotyphlopidae and Typhlopidae are other groups where remnants of the pelvic girdle are present, sometimes appearing as horny projections when visible. The frontal limbs are nonexistent in all snakes,
and this loss is associated with the evolution of the 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. The Hox gene expression in the axial skeleton responsible for the development of the thorax became dominant early in snake evolution and 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 one to three neck vertebrae), making most of the snake's skeleton being composed of an extremely extended thorax. Ribs are found exclusively on the thoracic vertebrae. The neck, lumbar and pelvic vertebrae are very reduced in number (only two to ten lumbar and pelvic vertebrae are still present), while only a short tail remains of the caudal vertebrae, although the tail is still long enough to be of good use in many species, and is modified in some aquatic and tree dwelling species.
An alternative hypothesis, based on morphology, suggests the ancestors of snakes were related to mosasaurs — extinct aquatic reptiles from the Cretaceous—which in turn are thought to have derived from varanid lizards. Under this hypothesis, the fused, transparent eyelids of snakes are thought to have evolved to combat marine conditions (corneal water-loss through osmosis), while the external ears were lost through disuse in an aquatic environment, ultimately leading to an animal similar in appearance to sea snakes of today. In the Late Cretaceous, snakes recolonized land to appear as they are today. Fossil snake remains are known from early Late Cretaceous marine sediments, which is consistent with this hypothesis, particularly as they are older than the terrestrial Najash rionegrina. Similar skull structure, reduced/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. In recent years, genetic studies have indicated snakes are not as closely related to monitor lizards as it was once believed, and therefore not to mosasaurs, the proposed ancestor in the aquatic scenario of their evolution. However, there is more evidence linking mosasaurs to snakes than to varanids. Fragmentary remains that have been found from the Jurassic and Early Cretaceous indicate deeper fossil records for these groups, which may eventually refute either hypothesis.
The great diversity of modern snakes appeared in the Paleocene, correlating with the adaptive radiation of mammals following the extinction of the nonavian dinosaurs. One of the more common groups today, the colubrids, became particularly diverse due to their preying on rodents, a mammal group that has been particularly successful. There are over 2,900 species of snakes ranging as far northward as the Arctic Circle in Scandinavia and southward through Australia and Tasmania. Snakes can be found on every continent (with the exception of Antarctica), dwelling in the sea, and as high as 16,000 feet (4,900 m)in the Himalayan Mountains of Asia. There are numerous islands from which snakes are absent, such as Ireland, Iceland, and New Zealand.


Taxonomy

 

All modern snakes are grouped within the suborder Serpentes in Linnean taxonomy, part of the order Squamata, though their precise placement within squamates is controversial.
There are two infraorders of Serpentes: Alethinophidia and Scolecophidia. This separation is based on morphological characteristics and mitochondrial DNA sequence similarity. Alethinophidia is sometimes split into Henophidia and Caenophidia, with the latter consisting of "colubroid" snakes (colubrids, vipers, elapids, hydrophiids, and attractaspids) and acrochordids, while the other alethinophidian families comprise Henophidia. While not extant today, the Madtsoiidae, a family of giant, primitive, python-like snakes, was around until 50,000 years ago in Australia, represented by genera such as Wonambi.
There are numerous debates in the systematics within the group. 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.[6]

Skeleton

The skeleton of most snakes consists solely of the skull, hyoid, vertebral column, and ribs, though henophidian snakes retain vestiges of the pelvis and rear limbs. The skull of the snake consists of a solid and complete braincase, to which many of the other bones are only loosely attached, particularly the highly mobile jaw bones, which facilitate manipulation and ingestion of large prey items. 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 hyoid is a small bone located posterior and ventral to the skull, in the 'neck' region, which serves as an attachment for muscles of the snake's tongue, as it does in all other tetrapods.
The vertebral column consists of anywhere between 200–400 (or more) vertebrae. Tail vertebrae are comparatively few in number (often less than 20% of the total) and lack ribs, while body vertebrae each have two ribs articulating with them. 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.Caudal autotomy in snakes is rare and is intervertebral, unlike that in lizards, which is intravertebral—that is, the break happens along a predefined fracture plane present on a vertebra.
In some snakes, most notably boas and pythons, there are vestiges of the hindlimbs in the form of a pair of pelvic spurs. These small, claw-like protrusions on each side of the cloaca are the external portion of the vestigial hindlimb skeleton, which includes the remains of an ilium and femur.

Internal organs

The snake's heart is encased in a sac, called the pericardium, located at the bifurcation of the bronchi. The heart is able to move around, however, owing to the lack of a diaphragm. This adjustment protects the heart from potential damage when large ingested prey is passed through the esophagus. The spleen is attached to the gall bladder and pancreas and filters the blood. The thymus gland is located in fatty tissue above the heart and is responsible for the generation of immune cells in the blood. The cardiovascular system of snakes is also unique for the presence of a renal portal system in which the blood from the snake's tail passes through the kidneys before returning to the heart.
The vestigial left lung is often small or sometimes even absent, as snakes' tubular bodies require all of their organs to be long and thin. In the majority of species, only one lung is functional. This lung contains a vascularized anterior portion and a posterior portion that does not function in gas exchange. This 'saccular lung' is used for hydrostatic purposes to adjust buoyancy in some aquatic snakes and its function remains unknown in terrestrial species. Many organs that are paired, such as kidneys or reproductive organs, are staggered within the body, with one located ahead of the other. Snakes have no lymph nodes.

Size

The now extinct Titanoboa cerrejonensis snakes found were 12–15 meters (39–49 ft) in length. By comparison, the largest extant snakes are the reticulated python, which measures about 9 meters (30 ft) long, and the anaconda, which measures about 7.5 meters (25 ft) long and is considered the heaviest snake on Earth. At the other end of the scale, the smallest extant snake is Leptotyphlops carlae, with a length of about 10 centimeters (4 in). Most snakes are fairly small animals, approximately 3 feet in length.

Skin

Main article: Snake scales
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 "spectacle" scales, which remain permanently closed, also known as brille.
The shedding of scales is called ecdysis (or in normal usage, moulting or sloughing). In the case of snakes, the complete outer layer of skin is shed in one layer. Snake scales are not discrete, but extensions of the epidermis—hence they are not shed separately but as a complete outer layer during each moult, akin to a sock being turned inside out.
The shape and number of scales on the head, back, and belly are often characteristic and used for taxonomic purposes. Scales are named mainly according to their positions on the body. In "advanced" (Caenophidian) snakes, the broad belly scales and rows of dorsal scales correspond to the vertebrae, allowing scientists to count the vertebrae without dissection.

Snakes' eyes are covered by their clear scales (the brille) rather than movable eyelids. Their eyes are always open, and for sleeping, the retina can be closed or the face buried among the folds of the body.

Moulting

Moulting 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.
Moulting occurs periodically throughout a snake's life. Before a moult, 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 "crawls" out of its old skin. 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.
An older snake may shed its skin only once or twice a year. But a younger snake, still growing, may shed up to four times a year. The discarded skin gives a perfect imprint of the scale pattern, and it is usually possible to identify the snake if the discarded skin is reasonably intact. This periodic renewal has led to the snake being a symbol of healing and medicine, as pictured in the Rod of Asclepius.

Perception

Eyesight
Snake vision varies greatly, from only being able to distinguish light from dark to keen eyesight, but the main trend is that their vision is adequate although not sharp, and allows them to track movements.Generally, vision is best in arboreal snakes and weakest in burrowing snakes. 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.
Smell
Snakes use smell to track their prey. They smell by using their forked tongues to collect airborne particles, then passing them to the vomeronasal organ orJacobson's organ in the mouth for examination. The fork in the tongue gives snakes a sort of directional sense of smell and taste simultaneously. They keep their tongues constantly in motion, sampling particles from the air, ground, and water, analyzing the chemicals found, and determining the presence of prey or predators in the local environment.
Vibration sensitivity
The part of the body in direct contact with the ground is very sensitive to vibration; thus, a snake can sense other animals approaching by detecting faint vibrations in the air and on the ground.
Infrared sensitivity
Pit vipers, pythons, and some boas have infrared-sensitive receptors in deep grooves between the nostril and eye, although some have labial pits on their upper lip just below the nostrils (common in pythons), which allow them to "see" the radiated heat of warm-blooded prey mammals.

Venom

See also: Snake venom
Cobras, vipers, and closely related species use venom to immobilize or kill their prey. The venom is modified saliva, delivered through fangs. The fangs of 'advanced' venomous snakes like viperids and elapids are hollow to inject venom more effectively, while the fangs of rear-fanged snakes such as the boomslang merely have a groove on the posterior edge to channel venom into the wound. Snake venoms are often prey specific, their role in self-defense is secondary. Venom, like all salivary secretions, is a predigestant that initiates the breakdown of food into soluble compounds, facilitating proper digestion. Even nonvenomous snake bites (like any animal bite) will cause tissue damage.
Certain birds, mammals, and other snakes such as kingsnakes that prey on venomous snakes have developed resistance and even immunity to certain venoms. Venomous snakes include three families of snakes, and do not constitute a formal classification group used in taxonomy. The term poisonous snake is mostly incorrect; poison is inhaled or ingested, whereas venom is injected. There are, however, two exceptions—Rhabdophis sequesters toxins from the toads it eats, then secretes them from nuchal glands to ward off predators, and a small population of garter snakes in Oregon retains enough toxin in their liver from the newts they eat to be effectively poisonous to local small predators such as crows and foxes.
Snake venoms are complex mixtures of proteins, and are stored in poison glands at the back of the head. In all venomous snakes, these glands open through ducts into grooved or hollow teeth in the upper jaw.These proteins can potentially be a mix of neurotoxins (which attack the nervous system), hemotoxins (which attack the circulatory system), cytotoxins, bungarotoxins and many other toxins that affect the body in different ways. Almost all snake venom contains hyaluronidase, an enzyme that ensures rapid diffusion of the venom.
Venomous snakes that use hemotoxins usually have the fangs that secrete the venom in the front of their mouths, making it easier for them to inject the venom into their victims.Some snakes that use neurotoxins, such as the mangrove snake, have their fangs located in the back of their mouths, with the fangs curled backwards. This makes it both difficult for the snake to use its venom and for scientists to milk them. Elapid snakes, however, such as cobras and kraits are proteroglyphous, possessing hollow fangs that cannot be erected toward the front of their mouths and cannot "stab" like a viper; they must actually bite the victim.
It has recently been suggested that all snakes may be venomous to a certain degree, with harmless snakes having weak venom and no fangs. Most snakes currently labelled “nonvenomous” would still be considered harmless according to this theory, as these snakes either lack a delivery method for the venom or are simply incapable of delivering enough to endanger a human. This theory postulates snakes may have evolved from a common lizard ancestor that was venomous, from which venomous lizards like the gila monster and beaded lizard may also have derived, as well as the monitor lizards and now extinct mosasaurs. They share this venom clade with various other saurian species.
Venomous snakes are classified in two taxonomic families:
There is a third family containing the opistoglyphous (rear-fanged) snakes as well as the majority of other snake species:

Behavior

Feeding and diet


All snakes are strictly carnivorous, eating small animals including lizards, other snakes, small mammals, birds, eggs, fish, snails or insects.Because snakes cannot bite or tear their food to pieces, they must swallow prey whole. The body size of a snake has a major influence on its eating habits. Smaller snakes eat smaller prey. Juvenile pythons might start out feeding on lizards or mice and graduate to small deer or antelope as an adult, for example.
The snake's jaw is a complex structure. Contrary to the popular belief that snakes can dislocate their jaws, snakes have a very flexible lower jaw, the two halves of which are not rigidly attached, and numerous other joints in their skull (see snake skull), allowing them to open their mouths wide enough to swallow their prey whole, even if it is larger in diameter than the snake itself, as snakes do not chew. For example, the African egg-eating snake has flexible jaws adapted for eating eggs much larger than the diameter of its head. This snake has no teeth, but does have bony protrusions on the inside edge of its spine, which it uses to break shells when it eats eggs.
While the majority of snakes eat a variety of prey animals, there is some specialization by some species. King cobras and the Australian bandy-bandy consume other snakes. Pareas iwesakii and other snail-eating colubrids of subfamily Pareatinae have more teeth on the right side of their mouths than on the left, as the shells of their prey usually spiral clockwise
Some snakes have a venomous bite, which they use to kill their prey before eating it. Other snakes kill their prey by constriction. Still others swallow their prey whole and alive.
After eating, snakes become dormant while the process of digestion takes place. Digestion is an intense activity, especially after consumption of large prey. In species that feed only sporadically, the entire intestine enters a reduced state between meals to conserve energy. The digestive system is then 'up-regulated' to full capacity within 48 hours of prey consumption. Being ectothermic (“cold-blooded”), the surrounding temperature plays a large role in snake digestion. The ideal temperature for snakes to digest is 30 °C (86 °F). So much metabolic energy is involved in a snake's digestion that in the Mexican rattlesnake (Crotalus durissus), surface body temperature increases by as much as 1.2 °C (2.2 °F) during the digestive process. Because of this, a snake disturbed after having eaten recently will often regurgitate its prey to be able to escape the perceived threat. When undisturbed, the digestive process is highly efficient, with the snake's digestive enzymes dissolving and absorbing everything but the prey's hair (or feathers) and claws, which are excreted along with waste.

Locomotion

The lack of limbs does not impede the movement of snakes. They have developed several different modes of locomotion to deal with particular environments. Unlike the gaits of limbed animals, which form a continuum, each mode of snake locomotion is discrete and distinct from the others; transitions between modes are abrupt.

Lateral undulation

Main article: Undulatory locomotion
Lateral undulation is the sole mode of aquatic locomotion, and the most common mode of terrestrial locomotion. In this mode, the body of the snake alternately flexes to the left and right, resulting in a series of rearward-moving "waves."While this movement appears rapid, snakes have rarely been documented moving faster than two body-lengths per second, often much less. This mode of movement has the same net cost of transport (calories burned per meter moved) as running in lizards of the same mass.
Terrestrial
Terrestrial lateral undulation is the most common mode of terrestrial locomotion for most snake species. In this mode, the posteriorly moving waves push against contact points in the environment, such as rocks, twigs, irregularities in the soil, etc.[ Each of these environmental objects, in turn, generates a reaction force directed forward and towards the midline of the snake, resulting in forward thrust while the lateral components cancel out. The speed of this movement depends upon the density of push-points in the environment, with a medium density of about 8 along the snake's length being ideal. The wave speed is precisely the same as the snake speed, and as a result, every point on the snake's body follows the path of the point ahead of it, allowing snakes to move through very dense vegetation and small openings.
Aquatic
Main article: Sea snake

When swimming, the waves become larger as they move down the snake's body, and the wave travels backwards faster than the snake moves forwards. Thrust is generated by pushing their body against the water, resulting in the observed slip. In spite of overall similarities, studies show that the pattern of muscle activation is different in aquatic versus terrestrial lateral undulation, which justifies calling them separate modes. All snakes can laterally undulate forward (with backward-moving waves), but only sea snakes have been observed reversing the motion (moving backwards with forward-moving waves).

Sidewinding

See also: Sidewinding

Most often employed by colubroid snakes (colubrids, elapids, and vipers) when the snake must move in an environment that lacks irregularities to push against (rendering lateral undulation impossible), such as a slick mud flat, or a sand dune. Sidewinding is a modified form of lateral undulation in which all of the body segments oriented in one direction remain in contact with the ground, while the other segments are lifted up, resulting in a peculiar "rolling" motion. This mode of locomotion overcomes the slippery nature of sand or mud by pushing off with only static portions on the body, thereby minimizing slipping. The static nature of the contact points can be shown from the tracks of a sidewinding snake, which show each belly scale imprint, without any smearing. This mode of locomotion has very low caloric cost, less than ⅓ of the cost for a lizard or snake to move the same distance.Contrary to popular belief, there is no evidence that sidewinding is associated with the sand being hot.

Concertina

Main article: Concertina movement
When push-points are absent, but there is not enough space to use sidewinding because of lateral constraints, such as in tunnels, snakes rely on concertina locomotion.In this mode, the snake braces the posterior portion of its body against the tunnel wall while the front of the snake extends and straightens. The front portion then flexes and forms an anchor point, and the posterior is straightened and pulled forwards. This mode of locomotion is slow and very demanding, up to seven times the cost of laterally undulating over the same distance. This high cost is due to the repeated stops and starts of portions of the body as well as the necessity of using active muscular effort to brace against the tunnel walls.

Rectilinear

Main article: Rectilinear locomotion
The slowest mode of snake locomotion is rectilinear locomotion, which is also the only one where the snake does not need to bend its body laterally, though it may do so when turning. In this mode, the belly scales are lifted and pulled forward before being placed down and the body pulled over them. Waves of movement and stasis pass posteriorly, resulting in a series of ripples in the skin. The ribs of the snake do not move in this mode of locomotion and this method is most often used by large pythons, boas, and vipers when stalking prey across open ground as the snake's movements are subtle and harder to detect by their prey in this manner.

Other

The movement of snakes in arboreal habitats has only recently been studied.While on tree branches, snakes use several modes of locomotion depending on species and bark texture. In general, snakes will use a modified form of concertina locomotion on smooth branches, but will laterally undulate if contact points are available. Snakes move faster on small branches and when contact points are present, in contrast to limbed animals, which do better on large branches with little 'clutter'.
Gliding snakes (Chrysopelea) of Southeast Asia launch themselves from branch tips, spreading their ribs and laterally undulating as they glide between trees. These snakes can perform a controlled glide for hundreds of feet depending upon launch altitude and can even turn in midair.


Reproduction

Although a wide range of reproductive modes are used by snakes, all snakes employ internal fertilization. This is accomplished by means of paired, forked hemipenes, which are stored, inverted, in the male's tail. The hemipenes are often grooved, hooked, or spined in order to grip the walls of the female's cloaca.
Most species of snakes lay eggs, but most snakes abandon the eggs shortly after laying. However, a few species (such as the King cobra) actually construct nests and stay in the vicinity of the hatchlings after incubation.Most pythons coil around their egg-clutches and remain with them until they hatch. A female python will not leave the eggs, except to occasionally bask in the sun or drink water. She will even “shiver” to generate heat to incubate the eggs.
Some species of snake are ovoviviparous and retain the eggs within their bodies until they are almost ready to hatch. Recently, it has been confirmed that several species of snake are fully viviparous, such as the boa constrictor and green anaconda, nourishing their young through a placenta as well as a yolk sac, which is highly unusual among reptiles, or anything else outside of placental mammals. Retention of eggs and live birth are most often associated with colder environments, as the retention of the young within the female.

Interactions with humans

Bite

Main article: Snakebite

Snakes do not ordinarily prey on humans, and most will not attack humans unless the snake is startled or injured, preferring instead to avoid contact. With the exception of large constrictors, nonvenomous snakes are not a threat to humans. The bite of nonvenomous snakes is usually harmless because their teeth are designed for grabbing and holding, rather than tearing or inflicting a deep puncture wound. Although the possibility of an infection and tissue damage is present in the bite of a nonvenomous snake, venomous snakes present far greater hazard to humans.
Documented deaths resulting from snake bites are uncommon. Nonfatal bites from venomous snakes may result in the need for amputation of a limb or part thereof. Of the roughly 725 species of venomous snakes worldwide, only 250 are able to kill a human with one bite. Australia averages only one fatal snake bite per year. In India, 250,000 snakebites are recorded in a single year, with as many as 50,000 recorded initial deaths.
The treatment for a snakebite is as variable as the bite itself. The most common and effective method is through antivenom (or antivenin), a serum made from the venom of the snake. Some antivenom is species specific (monovalent) while some is made for use with multiple species in mind (polyvalent). In the United States for example, all species of venomous snakes are pit vipers, with the exception of the coral snake. To produce antivenom, a mixture of the venoms of the different species of rattlesnakes, copperheads, and cottonmouths is injected into the body of a horse in ever-increasing dosages until the horse is immunized. Blood is then extracted from the immunized horse; the serum is separated and further purified and freeze-dried. It is reconstituted with sterile water and becomes antivenom. For this reason, people who are allergic to horses cannot be treated using antivenom. Antivenom for the more dangerous species (such as mambas, taipans, and cobras) is made in a similar manner in India, South Africa, and Australia, although these antivenoms are species-specific.

Snake charmers

Main article: Snake charming

In some parts of the world, especially in India, snake charming is a roadside show performed by a charmer. In such a show, the snake charmer carries a basket that contains a snake that he seemingly charms by playing tunes from his flutelike musical instrument, to which the snake responds.Snakes lack external ears, though they do have internal ears, and respond to the movement of the flute, not the actual noise.
The Wildlife Protection Act of 1972 in India technically proscribes snake charming on grounds of reducing animal cruelty. Other snake charmers also have a snake and mongoose show, where both the animals have a mock fight; however, this is not very common, as the snakes, as well as the mongooses, may be seriously injured or killed. Snake charming as a profession is dying out in India because of competition from modern forms of entertainment and environment laws proscribing the practice.

Trapping

The Irulas tribe of Andhra Pradesh and Tamil Nadu in India have been hunter-gatherers in the hot, dry plains forests, and have practiced the art of snake catching for generations. They have a vast knowledge of snakes in the field. They generally catch the snakes with the help of a simple stick. Earlier, the Irulas caught thousands of snakes for the snake-skin industry. After the complete ban on snake-skin industry in India and protection of all snakes under the Indian Wildlife (Protection) Act 1972, they formed the Irula Snake Catcher's Cooperative and switched to catching snakes for removal of venom, releasing them in the wild after four extractions. The venom so collected is used for producing life-saving antivenom, biomedical research and for other medicinal products. The Irulas are also known to eat some of the snakes they catch and are very useful in rat extermination in the villages.
Despite the existence of snake charmers, there have also been professional snake catchers or wranglers. Modern-day snake trapping involves a herpetologist using a long stick with a V- shaped end. Some television show hosts, like Bill Haast, Austin Stevens, Steve Irwin, and Jeff Corwin, prefer to catch them using bare hands.

Consumption


While not commonly thought of as food in most cultures, in some cultures, the consumption of snakes is acceptable, or even considered a delicacy, prized for its alleged pharmaceutical effect of warming the heart. Snake soup of Cantonese cuisine is consumed by local people in autumn, to warm up their body. Western cultures document the consumption of snakes under extreme circumstances of hunger.Cooked rattlesnake meat is an exception, which is commonly consumed in parts of the Midwestern United States. In Asian countries such as China, Taiwan, Thailand, Indonesia, Vietnam and Cambodia, drinking the blood of snakes—particularly the cobra—is believed to increase sexual virility. The blood is drained while the cobra is still alive when possible, and is usually mixed with some form of liquor to improve the taste.
In some Asian countries, the use of snakes in alcohol is also accepted. In such cases, the body of a snake or several snakes is left to steep in a jar or container of liquor. It is claimed that this makes the liquor stronger (as well as more expensive). One example of this is the Habu snake sometimes placed in the Okinawan liquor Awamori also known as "Habu Sake."[69]
U.S. Army Special Forces trainees are taught to catch, kill, and eat snakes during their survival course; this has earned them the nickname "snake eaters," which the video game Metal Gear Solid 3: Snake Eater may be implied to draw off of.

Pets

In the Western world, some snakes (especially docile species such as the ball python and corn snake) are kept as pets. To meet this demand a captive breeding industry has developed. Snakes bred in captivity tend to make better pets and are considered preferable to wild caught specimens.Snakes can be very low maintenance pets, especially compared to more traditional species. They require minimal space, as most common species do not exceed five feet in length. Pet snakes can be fed relatively infrequently, usually once every 5–14 days. Certain snakes have a lifespan of more than 40 years if given proper care.

Symbolism

Main article: Serpent (symbolism)
In Egyptian history, the snake occupies a primary role with the Nile cobra adorning the crown of the pharaoh in ancient times. It was worshipped as one of the gods and was also used for sinister purposes: murder of an adversary and ritual suicide (Cleopatra).

In Greek mythology snakes are often associated with deadly and dangerous antagonists, but this is not to say that snakes are symbolic of evil; in fact, snakes are 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 also depicted in art with snakes instead of legs and feet for the same reason—they are children of Gaia and Ouranos (Uranus), so they are bound to the earth.
Three medical symbols involving snakes that are still used today are Bowl of Hygieia, symbolizing pharmacy, and the Caduceus and Rod of Asclepius, which are symbols denoting medicine in general.
India is often called the land of snakes and is steeped in tradition regarding snakes. Snakes are worshipped as gods even today with many women pouring milk on snake pits (despite snakes' aversion for milk). The cobra is seen on the neck of Shiva and Vishnu is depicted often as sleeping on a seven-headed snake or within the coils of a serpent.There are also several temples in India solely for cobras sometimes called Nagraj (King of Snakes) and it is believed that snakes are symbols of fertility. There is a Hindu festival called Nag Panchami each year on which day snakes are venerated and prayed to. See also Nāga.
In India there is another mythology about snakes. Commonly known in Hindi as "Ichchhadhari" snakes. Such snakes can take the form of any living creature, but prefer human form. These mythical snakes possess a valuable gem called "Mani", which is more brilliant than diamond. There are many stories in India about greedy people trying to possess this gem and ending up getting killed.
The Ouroboros is a symbol associated with many different religions and customs, and is claimed to be related to Alchemy. The Ouroboros or Oroboros is a snake eating its own tail in a clock-wise direction (from the head to the tail) in the shape of a circle, representing manifestation of one's own life and rebirth, leading to immortality.
The snake is one of the 12 celestial animals of Chinese Zodiac, in the Chinese calendar.
Many ancient Peruvian cultures worshipped nature. They emphasized animals and often depicted snakes in their art.

Religion


Snakes are a part of Hindu worship. A festival Nag Panchami is celebrated every year on snakes. Most images of Lord Shiva depict snake around his neck. Puranas have various stories associated with Snakes. In the Puranas, Shesha is said to hold all the planets of the Universe on his hoods and to constantly sing the glories of Vishnu from all his mouths. He is sometimes referred to as "Ananta-Shesha," which means "Endless Shesha." Other notable snakes in Hinduism are Ananta, Vasuki, Taxak, Karkotaka and Pingala. The term Nāga is used to refer to entities that take the form of large snakes in Hinduism and Buddhism.

Snakes have also been widely revered, such as in ancient Greece, where the serpent was seen as a healer, and Asclepius carried two intertwined on his wand, a symbol seen today on many ambulances.
In Judaism, the snake of brass is also a symbol of healing, of one's life being saved from imminent death (Book of Numbers 26:6–9).

In Christianity, Christ's redemptive work is compared to saving one's life through beholding the Nehushtan (serpent of brass) (Gospel of John 3:14). Snake handlers use snakes as an integral part of church worship in order to exhibit their faith in divine protection. However, more commonly in Christianity, the serpent has been seen as a representative of evil and sly plotting, which can be seen in the description in Genesis chapter 3 of a snake in the Garden of Eden tempting Eve. Saint Patrick is reputed to have expelled all snakes from Ireland while Christianising the country in the 5th century, thus explaining the absence of snakes there.
In Christianity and Judaism, the snake makes its infamous appearance in the first book (Genesis 3:1) of the Bible when a serpent appears before the first couple Adam and Eve and tempts them with the forbidden fruit from the Tree of Knowledge. The snake returns in Exodus when Moses, as a sign of God's power, turns his staff into a snake and when Moses made the Nehushtan, a bronze snake on a pole that when looked at cured the people of bites from the snakes that plagued them in the desert. The serpent makes its final appearance symbolizing Satan in the Book of Revelation: "And he laid hold on the dragon the old serpent, which is the devil and Satan, and bound him for a thousand years." (Revelation 20:2)
In Neo-Paganism and Wicca, the snake is seen as a symbol of wisdom and knowledge.

Place names

Various locations in different countries are called for snakes, such as the Snake River in the United States and Snake Island (Black Sea) (derived from "Fidonisi," which means the same in Greek).

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Antivenom
From Wikipedia, the free encyclopedia

Antivenom (or antivenin or antivenene) is a biological product used in the treatment of venomous bites or stings. Antivenom is created by milking venom from the desired snake, spider or insect. The venom is then diluted and injected into a horse, goat or cat. The subject animal will undergo an immune response to the venom, producing antibodies against the venom's active molecule which can then be harvested from the animal's blood and used to treat envenomation. Internationally, antivenoms must conform to the standards of Pharmacopoeia and the World Health Organization (WHO).

Terminology

The name "antivenin" comes from the French word "venin", meaning venom, and historically "antivenin" was predominant around the world. In 1981, the World Health Organization decided that the preferred terminology in the English language would be "venom" and "antivenom" rather than "venin/antivenin" or "venen/antivenene".

Therapeutic use

The principle of antivenom is based on that of vaccines, developed by Edward Jenner; however, instead of inducing immunity in the patient directly, it is induced in a host animal and the hyperimmunized serum is transfused into the patient.
Antivenoms can be classified into monovalent (when they are effective against a given species' venom) or polyvalent (when they are effective against a range of species, or several different species at the same time). The first antivenom for snakes (called an anti-ophidic serum) was developed by Albert Calmette, a French scientist of the Pasteur Institute working at its Indochine branch in 1895, against the Indian Cobra (Naja naja). Vital Brazil, a Brazilian scientist, developed in 1901 the first monovalent and polyvalent antivenoms for Central and South American Crotalus, Bothrops and Elaps genera, as well as for certain species of venomous spiders, scorpions, and frogs. They were all developed in a Brazilian institution, the Instituto Butantan, located in São Paulo, Brazil.
Antivenoms for therapeutic use are often preserved as freeze-dried ampoules, but some are available only in liquid form and must be kept refrigerated. (They are not immediately inactivated by heat, so a minor gap in the cold chain is not disastrous.) The majority of antivenoms (including all snake antivenoms) are administered intravenously; however, stonefish and redback spider antivenoms are given intramuscularly. The intramuscular route has been questioned in some situations as not uniformly effective.
Antivenoms bind to and neutralize the venom, halting further damage, but do not reverse damage already done. Thus, they should be administered as soon as possible after the venom has been injected, but are of some benefit as long as venom is present in the body. Since the advent of antivenoms, some bites which were previously inevitably fatal have become only rarely fatal provided that the antivenom is administered soon enough.
Antivenoms are purified by several processes but will still contain other serum proteins that can act as antigens. Some individuals may react to the antivenom with an immediate hypersensitivity reaction (anaphylaxis) or a delayed hypersensitivity (serum sickness) reaction and antivenom should, therefore, be used with caution. Despite this caution, antivenom is typically the sole effective treatment for a life-threatening condition, and once the precautions for managing these reactions are in place, an anaphylactoid reaction is not grounds to refuse to give antivenom if otherwise indicated. Although it is a popular myth that a person allergic to horses "cannot" be given antivenom, the side effects are manageable, and antivenom should be given as rapidly as the side effects can be managed.
Sheep are generally used in preference over horses now, however, as the potential for adverse immunological responses in humans from sheep-derived antibodies is generally somewhat less than that from horse-derived antibodies. The use of horses to raise antibodies - in Australia at least, where much antivenom research has been undertaken (by Sutherland and others for example) - has been attributed to the research base originally having been a large number of veterinary officers. These vets had, in many cases, returned from taking part in the Boer and First World Wars and were generally experienced with horses due to working with cavalry. The large animal vets were similarly oriented given the use of horses as a prime source of motive power and transport, especially in the rural setting. The overall experience with horses naturally made them the preferred subject in which to raise antibodies. It was not until later that the immuno-reactivity of certain horse serum proteins was assessed to be sufficiently problematic that alternatives in which to raise antibodies were investigated.[citation needed]
In the U.S. the only approved antivenom for pit viper (rattlesnake, copperhead and water moccasin) snakebite is based on a purified product made in sheep known as CroFab. It was approved by the FDA in October, 2000. U.S. coral snake antivenom is no longer manufactured, and remaining stocks of in-date antivenom for coral snakebite expired in the Fall of 2009, leaving the U.S. without a Coral snake antivenom. Efforts are being made to obtain approval for a coral snake antivenom produced in Mexico which would work against U.S. coral snakebite, but such approval remains speculative. In the absence of antivenom, all coral snakebite should be treated in a hospital by elective endotracheal intubation and mechanical ventilation until the effects of coral snake neurotoxins abate. It is important to remember that respiratory paralysis in coral snakebite can occur suddenly, often up to 12 or more hours after the bite, so intubation and ventilation should be employed in anticipation of respiratory failure and not after it occurs, when it may be too late.

Veterinary Antivenom

The United States Department of Agriculture (USDA) regulates veterinary antibody and antivenom products based on the Virus Serum Toxin Act. Currently, Fort Dodge Animal Health has received a United States Veterinary License Number for an equine derived antivenom labeled for canine use. Animal Health Consulting, LLC is coordinating the trials for a new pit viper antivenom for veterinary medicine

Natural and acquired immunity

Although individuals can vary in their physiopathological response and sensitivity to animal venoms, there is no natural immunity to them in humans. Some ophiophagic animals are immune to the venoms produced by some species of venomous snakes, by the presence of antihemorrhagic and antineurotoxic factors in their blood. These animals include King snakes, opossums, mongooses, and hedgehogs.[citation needed]
It is quite possible to immunize a person directly with small and graded doses of venom rather than an animal. According to Greek history, King Mithridates did this in order to protect himself against attempts of poisoning, therefore this procedure is often called mithridatization. However, unlike a vaccination against disease which must only produce a latent immunity that can be roused in case of infection, to neutralize a sudden and large dose of venom requires maintaining a high level of circulating antibody (a hyperimmunized state), through repeated venom injections (typically every 21 days). The long-term health effects of this process have not been studied. For some large snakes, the total amount of antibody it is possible to maintain in one human being is not enough to neutralize one envenomation[citation needed]. Further, cytotoxic venom components can cause pain and minor scarring at the immunization site. Finally, the resistance is specific to the particular venom used; maintaining resistance to a variety of venoms requires multiple monthly venom injections. Thus, there is no practical purpose or favorable cost/benefit ratio for this, except for people like zoo handlers, researchers, and circus artists who deal closely with venomous animals. Mithridatization has been tried with success in Australia and Brazil and total immunity has been achieved even to multiple bites of extremely venomous cobras and pit vipers. Starting in 1950, Bill Haast successfully immunized himself to the venoms of Cape, Indian and King cobras[citation needed].
Because neurotoxic venoms must travel farther in the body to do harm and are produced in smaller quantities, it is easier to develop resistance to them than directly cytotoxic venoms (such as those of most vipers) that are injected in large quantity and do damage immediately upon injection.
 


Antivenom sources

The following groups assist in locating antivenoms:


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Venomous snake
From Wikipedia, the free encyclopedia

A venomous snake is a snake that uses modified saliva, snake venom, usually delivered through highly specialized teeth such as hollow fangs, for the purpose of prey immobilization and self-defense. In contrast, non-venomous species either constrict their prey, or simply overpower it with their jaws.
Venomous snakes include several families of snakes and do not form a single taxonomic group. This has been interpreted to mean that venom in snakes originated more than once as the result of convergent evolution. Evidence has recently been presented for the Toxicofera hypothesis however; venom was present (in small amounts) in the ancestor of all snakes (as well as several lizard families) as 'toxic saliva' and evolved to extremes in those snake families normally classified as venomous by parallel evolution. The Toxicofera hypothesis further implies that 'non venomous' snake lineages have either lost the ability to produce venom (but may still have lingering venom pseudogenes), or actually do produce venom in small quantities, likely sufficient to assist in small prey capture, but cause no harm to humans if bitten.
Venomous snakes are often said to be poisonous, although this is not the correct term, as venoms and poisons are different. Poisons can be absorbed by the body, such as through the skin or digestive system, while venoms must first be introduced directly into tissues or the blood stream (envenomated) through mechanical means. It is, for example, therefore harmless to drink snake venom as long as there are no lacerations inside the mouth or digestive tract. There are however two exceptions: the Rhabdophis snakes (keelback snakes) secrete poison from glands that it gets from the poisonous toads that it preys on; similarly certain garter snakes from Oregon retain toxins in their liver from the newts they eat.
Many other snakes, such as boas and pythons may not be venomous, but their bites should be attended to medically. Their teeth may be long and sharp, capable of inflicting lacerations, with bites often introducing mouth bacteria and shed teeth into the wound.

Most venomous snakes

Lists or rankings of the world's "most venomous snakes" are tentative and differ greatly due to numerous factors, including the recentness and reliability of the data, the number of species analyzed, and the testing methods used.In terms of human fatalities and many other factors, the most venomous species may not always be the most dangerous; for example, while the Russell's viper and the Saw-scaled viper have a significantly weaker venom than the inland taipan, they are responsible for far more deaths due to its wide distribution.
While there have been numerous studies on snake venom, potency estimates can vary,creating overlap and greatly complicating the task. Further, LD50 may be measured through intramuscular, intraperitoneal, intravenous or subcutaneous injections on small rodents, although the latter is the most applicable to actual bites. It should also be considered that mice, the most commonly used animals in determining LD50, may react to some snake venoms differently than humans do.Thus, it remains difficult to compile such lists.
Many of these lists only take into account of terrestrial and arboreal snakes and neglect to list the of venom of the sea snakes. Species of sea snakes have been listed to have more toxic venom than even that of the inland taipan.

Families of venomous snakes

Over 600 species are known to be venomous—about a quarter of all snake species. The following table lists some species which are well-known for their highly toxic venom or danger.


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Blue-tongued skink
From Wikipedia, the free encyclopedia

Blue-tongued skinks comprise the Australasian genus, Tiliqua, which contains some of the largest members of the skink family (Scincidae). They are commonly called blue-tongued lizards or simply blue-tongues in Australia. As suggested by these common names, a prominent characteristic of the genus is a large blue tongue that can be bared as a bluff-warning to potential enemies.

Systematics and Distribution

Blue-tongued skinks are closely related to the genera Cyclodomorphus and Hemisphaeriodon. All species are found on mainland Australia with the exception of Tiliqua gigas which occurs in New Guinea and various islands of Indonesia. One subspecies of Tiliqua scincoides is also found on several small Indonesian islands between Australia and New Guinea. Tiliqua nigrolutea is the only species present in Tasmania. With the exception of the pygmy blue-tongue, they are relatively large lizards (up to 37 cm total length), light-bodied, short-limbed, broad with a distinct head and dull teeth.

Ecology

Most species are diurnal ground-foraging omnivores, feeding on a wide variety of insects, gastropods, flowers, fruits and berries . The pygmy blue-tongue is again the exception, being primarily an ambush predator of terrestrial arthropods. All are viviparous, with litter sizes ranging from 1-4 in the pygmy blue-tongue and shingleback to 5-24 in the eastern and northern blue-tongues .

Species and subspecies


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Biawak
Dari Wikipedia bahasa Indonesia, ensiklopedia bebas


Biawak adalah sebangsa reptil yang masuk ke dalam golongan kadal besar, suku biawak-biawakan (Varanidae). Biawak dalam bahasa lain disebut sebagai bayawak (Sunda), menyawak atau nyambik (Jawa), berekai (Madura), dan monitor lizard atau goanna (Inggris).
Biawak banyak macamnya. Yang terbesar dan terkenal ialah biawak komodo (Varanus komodoensis), yang panjangnya dapat melebihi 3 m. Biawak ini, karena besarnya, dapat memburu rusa, babi hutan dan anak kerbau. Bahkan ada kasus-kasus di mana biawak komodo menyerang manusia, meskipun jarang. Biawak ini hanya menyebar terbatas di beberapa pulau kecil di Nusa Tenggara, seperti di p. Komodo, p. Padar, p. Rinca dan di ujung barat p. Flores.
Biawak yang kerap ditemui di desa-desa dan perkotaan di Indonesia barat kebanyakan adalah biawak air dari jenis Varanus salvator. Panjang tubuhnya (moncong hingga ujung ekor) umumnya hanya sekitar 1 m lebih sedikit, meskipun ada pula yang dapat mencapai 2,5 m.

Habitat dan Makanan

Biawak umumnya menghuni tepi-tepi sungai atau saluran air, tepian danau, pantai, dan rawa-rawa termasuk rawa bakau. Di perkotaan, biawak kerap pula ditemukan hidup di gorong-gorong saluran air yang bermuara ke sungai.
Biawak memangsa aneka serangga, ketam atau yuyu, berbagai jenis kodok, ikan, kadal, burung, serta mamalia kecil seperti tikus dan cerurut. Biawak pandai memanjat pohon. Di hutan bakau, biawak kerap mencuri telur atau memangsa anak burung. Biawak juga memakan bangkai, telur kura-kura, penyu atau buaya.

Kehidupan Biawak

Biawak berkembang biak dengan bertelur. Sebelum mengawini betinanya, biawak jantan biasanya berkelahi lebih dulu untuk memperlihatkan penguasaannya. Pertarungan biawak ini unik dan menarik, karena dilakukan sambil ‘berdiri’. Kedua biawak itu lalu saling pukul atau saling tolak sambil berdiri pada kaki belakangnya, sehingga tampak seperti menari bersama.
Telur-telur biawak disimpan di pasir atau lumpur di tepian sungai, bercampur dengan daun-daun busuk dan ranting. Panas dari sinar matahari dan proses pembusukan serasah akan menghangatkan telur, sehingga menetas.

Biawak dan Manusia

Biawak telah ratusan bahkan ribuan tahun diburu manusia. Orang terutama memanfaatkan kulitnya sebagai bahan perhiasan, dan dagingnya sebagai bahan makanan atau untuk obat. Pada waktu kini, perdagangan kulit biawak telah menghidupi beribu-ribu orang, mulai dari penangkap biawak di desa-desa, pengumpul, pengolah, eksportir, hingga industri kulit. Tidak kurang dari satu juta potong kulit biawak air dikumpulkan setiap tahunnya dari berbagai bagian dunia (Shine et al. 1996, Biological Conservation 77 : 125-134).
Biawak ditangkap orang dengan cara dijerat atau dikail. Jerat atau kail itu dipasang di tempat yang sering didatangi biawak. Seperti umumnya daging kadal, daging biawak juga dipercaya sebagai obat sakit kulit.

Jenis-jenis Biawak

Suku Varanidae terdiri atas dua kelompok yang sedikit berbeda, yalah dari marga Varanus yang besar (lebih dari 35 spesies di seluruh dunia), dan marga Lanthanotus yang sejauh ini berisi spesies tunggal L. borneensis dari Kalimantan. Marga yang kedua itu merupakan biawak yang bertubuh kecil (lk. 30 cm) dan tanpa lubang telinga.
Beberapa jenis biawak yang terdapat di Indonesia:
    • biawak komodo (Varanus komodoensis)
    • biawak kelabu (V. nebulosus)
    • biawak hitam (V. rudicollis)
    • biawak air (V. salvator)
 

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Landak
Dari Wikipedia bahasa Indonesia, ensiklopedia bebas
Langsung ke: navigasi, cari
Landak adalah hewan pengerat (Rodentia) yang memiliki rambut yang tebal dan berbentuk duri tajam. Hewan ini ditemukan di Asia, Afrika, maupun Amerika, dan cenderung menyebar di kawasan tropika. Landak merupakan hewan pengerat terbesar ketiga dari segi ukuran tubuh, setelah kapibara dan berang-berang. Hewan ini agak "membulat" serta tidak terlalu lincah apabila dibandingkan dengan tikus. Karena rambut durinya, hewan lain yang mirip namun bukan pengerat, seperti hedgehog dan landak semut (Echidna), juga dikenali sebagai "landak".
Landak secara umum adalah herbivora, dan menyukai daun, batang, khususnya bagian kulit kayu. Karena hal inilah banyak landak dianggap sebagai hama tanaman pertanian. Meskipun demikian, orang juga menjadikan landak sebagai salah satu bahan pangan. Sate landak merupakan salah satu menu khas dari Kabupaten Karanganyar.
Landak yang biasa dikenal orang adalah Hystrix, namun secara umum landak juga dipakai untuk menyebut anggota dari suku/famili Erethizontidae (landak Dunia Baru, marga: Coendou, Sphiggurus, Erethizon, Echinoprocta, dan Chaetomys) dan Hystricidae (landak Dunia Lama, marga: Atherurus, Hystrix, dan Trichys).

Klasifikasi


Bangsa Rodentia

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Hedgehog
From Wikipedia, the free encyclopedia



    A hedgehog is any of the spiny mammals of the subfamily Erinaceinae and the order Erinaceomorpha. There are 17 species of hedgehog in five genera, found through parts of Europe, Asia, Africa, and New Zealand. There are no hedgehogs native to Australia, and no living species native to North America; those in New Zealand are introduced. Hedgehogs have changed little over the last 15 million years. Like many of the first mammals they have adapted to a nocturnal, insectivorous way of life. The name 'hedgehog' came into use around the year 1450, derived from the Middle English 'heyghoge', from 'heyg', 'hegge' = hedge, because it frequents hedgerows, and 'hoge', 'hogge' = hog, from its piglike snout. Other names include 'urchin', 'hedgepig' and 'furze-pig' .

    Physical description

    Hedgehogs are easily recognized by their spines, which are hollow hairs made stiff with keratin. Their spines are not poisonous or barbed and, unlike the quills of a porcupine, cannot easily be removed from the hedgehog. However, spines normally come out when a hedgehog sheds baby spines and replaces them with adult spines. This is called "quilling." When under extreme stress or during sickness, a hedgehog can also lose spines.
    A defense that all species of hedgehogs possess is the ability to roll into a tight ball, causing all of the spines to point outwards. However, its effectiveness depends on the number of spines, and since some of the desert hedgehogs evolved to carry less weight, they are much more likely to try to run away and sometimes even attack the intruder, trying to ram into the intruder with its spines, and rolling as a last resort. This results in a different number of predators for different species: while forest hedgehogs have relatively few, primarily birds (especially owls) and ferrets, smaller species like the Long-eared Hedgehog are preyed on by foxes, wolves and mongooses.
    Hedgehogs are primarily nocturnal, although, depending on the species, they may be more or less active during the day. The hedgehog sleeps for a large portion of the daytime either under cover of bush, grass, rock or in a hole in the ground. Again, different species can have slightly different habits, but in general hedgehogs dig dens for shelter. All wild hedgehogs can hibernate, although not all do; hibernation depends on temperature, species, and abundance of food.
    The hedgehog's back is made up of two large muscles, which control the positioning of its quills. There are about 5,000 to 6,500 quills on the average hedgehog, and these are durable on the outside, while being filled with air pockets on the inside. The hedgehog uses its quills to protect itself from predators, using muscles which draw their quilled skin to cover their full body, and pulling in the parts of their bodies not covered, such as their head, feet, and belly.[4] This form of defense is the hedgehog's most successful, but is usually their last resort.
    Hedgehogs have many alternate defense mechanisms. In most situations a hedgehog will flee rather than confront a threat, rolled up in a ball or not. All hedgehogs possess the stamina to run, many can make 4.5 miles per hour or better, and are particularly adept at climbing steep walls, trees, and fences and even swimming.
    Hedgehogs are fairly vocal and communicate through a combination of grunts, snuffles and/or squeals, depending on species.
    Hedgehogs occasionally perform a ritual called anointing. When the animal encounters a new scent, it will lick and bite the source, then form a scented froth in its mouth and paste it on its spines with its tongue. It is unknown what the specific purpose of this ritual is, but some experts believe anointing camouflages the hedgehog with the new scent of the area and provides a possible poison or source of infection to predators poked by their spines. Anointing is sometimes also called anting because of a similar behavior in birds.
    Similar to opossums, mice, and moles, hedgehogs have some natural immunity against snake venom due to the protein erinacin in the animal's muscular system.
    In captivity, hedgehogs tend to get along with dogs, cats and other pets. On the rare occasions when they do feel threatened by these animals, the hedgehog will roll into a ball until the threatening animal disappears. Still, care should be taken to protect hedgehogs from particularly large, aggressive, or mischievous pets.

    Diet

    Although traditionally classified in the now abandoned order Insectivora, hedgehogs are not exclusively insectivores but are almost omnivorous. Hedgehogs feed on insects, snails, frogs and toads, snakes, bird eggs, carrion, mushrooms, grass roots, berries, melons, and watermelons. In fact, berries constitute a major part of an Afghan Hedgehog's diet in early spring after hibernation. The hedgehog is occasionally spotted after a rainstorm foraging for earthworms. Although forest hedgehogs, most well-known to Europeans, are indeed mainly insectivores, this is not necessarily true for other species.
    In areas that have hedgehogs in the wild, they are often welcomed as a natural form of garden pest control. Many people leave food out to attract hedgehogs and they will consume tinned cat or dog food (with a preference for chicken flavours, and a dislike of fish), chopped peanuts, and raisins. Pet food is preferable to dairy, but both are often too high in fat and too low in protein. It is best to leave out only a small treat, leaving them plenty of appetite for the pests in one's garden. Hedgehogs will welcome water as they will become quite thirsty. But make sure if your letting a hedgehog drink from a pool that there is a way out. Even though hedgehogs can swim they will get tired and drown.

    Reproduction and lifespan


    Depending on the species, the gestation period is 35–58 days. The average litter is 3–4 newborns for larger species and 5–6 for smaller ones. As with many animals, it is not unusual for an adult male hedgehog to kill newborn males.
    The hedgehog's dilemma is based on the apparent danger of a male hedgehog being injured by a spine while mating with a female hedgehog. However, this is not a problem for hedgehogs, as the male's penis is very near the center of its abdomen (often mistaken for a belly button) and the female can curl her tail upward until her vulva protrudes behind the rest of her body. Thus, the male does not have to get completely on top of the female when mating.
    Hedgehogs have a relatively long lifespan for their size. Larger species of hedgehogs live 4–7 years in the wild (some have been recorded up to 16 years), and smaller species live 2–4 years (4–7 in captivity), compared to a mouse at 2 years and a large rat at 3–5 years. Lack of predators and controlled diet contribute to a longer lifespan in captivity (8–10 years depending on size).
    Hedgehogs are born blind. The hedgehogs are birthed with a protective membrane covering their quills, which dries and shrinks over the next several hours. The infants are born with quills beneath the skin, like pimples, and pass the skin after they have been cleaned.[

    Predators

    Hedgehog bones have been found in the pellets of the European Eagle Owl.

    Domesticated hedgehogs

    Main article: Domesticated hedgehog
    The most common pet species of hedgehog are hybrids of the White-bellied Hedgehog or Four-toed Hedgehog (Atelerix albiventris) and the North African Hedgehog (A. algirus). It is smaller than the European Hedgehog, and thus is sometimes called the African Pygmy Hedgehog. Other species kept as pets are the Long-eared Hedgehog (Hemiechinus auritus) and the Indian Long-eared Hedgehog (H. collaris).
    Domesticated species prefer a warm climate (above 72 °F/22 °C but below 85 °F/29.5 °C) and do not naturally hibernate. They have an insectivorous diet. Commonly, this is replaced with cat food and ferret food and is supplemented by insects and other small animals. Today, many pet stores sell hedgehog mixes that are specifically formulated for hedgehogs. Crickets, mealworms, and pinkies (baby mice) are also favored treats. It is illegal to own a hedgehog as a pet in some U.S. states and some Canadian municipalities, and breeding licenses are required. No such restrictions exist in most European countries with the exception of Scandinavia.
    The purchase of Domesticated Hedgehogs has seen a considerable increase in the last few years, owing to their apparently innocent and playful looks. Hedgehogs are considered a low-maintenance pet. Their curiosity and need for stimuli make for quick adjustment to their owners, and their eating and waste habits make for a relatively clean housing environment for the pet. Overall they exhibit very few vulnerabilities to species-specific disease (although several do exist) and are easy to care for.

    Pest control


    Hedgehogs are a powerful form of pest control. A single hedgehog can keep an average garden free of pests by eating up to 200 grams of insects each night. It is common throughout the United Kingdom to see people attempting to lure hedgehogs into their gardens with treats and hedgehog-sized holes in their fences.[citation needed]
    One problem with using hedgehogs for garden pest control is the use of chemical insecticide. While the hedgehog is large enough to resist most insecticides, it cannot withstand them if it eats many insects which have become full of the poison. This causes many hedgehog deaths where pet hedgehogs eat contaminated bugs within the house.[citation needed]
    In areas where hedgehogs have been introduced, such as New Zealand and the islands of Scotland, the hedgehog itself has become a pest. In New Zealand it causes immense damage to native species including insects, snails, lizards and ground-nesting birds, particularly shore birds. As with many introduced animals, it lacks natural predators. With overpopulation, it kills off more insects than initially intended and expands its diet to include things such as snails, worms, and the eggs of wading birds.
    Correcting overpopulation is troublesome itself. Attempts to eliminate hedgehogs from bird colonies on the Scottish islands of North Uist and Benbecula in the Outer Hebrides were met with international outrage. Eradication began in 2003 with 690 hedgehogs being killed. Animal welfare groups attempted rescues to save the hedgehogs. By 2007, legal injunctions against the killing of hedgehogs were put in place. In 2008, the elimination process was changed from killing the hedgehogs to trapping them and releasing on the mainland.[11]

    Hedgehog diseases

    Hedgehogs suffer many diseases common to humans. These include cancer, fatty liver disease, and cardiovascular disease.
    Cancer is very common in hedgehogs. The most common is squamous cell carcinoma. Squamous cell spreads quickly from the bone to the organs in hedgehogs, unlike in humans. Surgery to remove the tumors is rare because it would result in removing too much bone structure.
    Fatty liver disease is believed by many to be caused by bad diet. Hedgehogs will eagerly eat foods that are high in fat and sugar. Having a metabolism adapted for low-fat, protein-rich insects, this leads to common problems of obesity. Fatty liver disease is one sign, heart disease is another.
    Hedgehogs uncommonly transmit a characteristic fungal skin infection to human handlers as well as other hedgehogs. This ringworm or dermatophytosis infection is caused by Trichophyton erinacei, which forms a distinct mating group within the Arthroderma benhamiae species complex.

    Human influence


    As with most small mammals living around humans, cars pose a great threat to hedgehogs. Many are run over as they attempt to cross roadways. Another common human-related fatality is pesticides.[citation needed] Hedgehogs that eat insects filled with pesticides will often develop digestive problems and eventually die.[citation needed]
    In 2006, McDonald's changed the design of their McFlurry containers to be more hedgehog-friendly. Previously, hedgehogs would get their heads stuck in the container as they tried to lick the remaining food from inside the cup. Then, being unable to get out, they would starve to death. Domesticated hedgehogs display this behavior by getting their head stuck in tubes (commonly, lavatory paper tubes) and walking around with the tube on their head. Hedgehog owners often refer to this as "tubing" and promote the behavior by supplying clean tubes. Most owners are considerate enough, however, to cut the tubes lengthwise so as to prevent the hedgehog from remaining trapped against their will. Curiously though, some will still knowingly get themselves stuck for a few hours.

    Culinary and medicinal use

    Hedgehogs are a food source in many cultures. Hedgehogs were eaten in Ancient Egypt, and some recipes of the Late Middle Ages call for hedgehog meat. In the Middle East and especially among Bedouins, hedgehog meat is considered medicinal, and thought to cure rheumatism and arthritis.Romani people supposedly still eat it, and also use the blood and the fat for its supposed medicinal value. One method for killing the animal suggests holding it up by one of its hind legs and cutting off the tip of its nose when it unrolls, which kills it and drains the blood at the same time. The animal is then cleaned and boiled or roasted.
    During the 1980s, "hedgehog-flavour" crisps were introduced in Britain, although the product did not in fact contain any hedgehog.

    Genera and species

    Subfamily Erinaceinae (Hedgehogs)


     












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