Showing posts with label most venomous snakes. Show all posts
Showing posts with label most venomous snakes. Show all posts

Monday, 26 March 2012

Acanthophis hawkei (Barkly Tableland Death Adder)

Acanthophis is a genus of elapid snakes. Commonly called death adders, they are native to Australia, New Guinea and nearby islands, and are among the most venomous snakes in the world. The name of the genus derives from the Ancient Greek acanthos/ἄκανθος "spine" and ophis/ὄφις "snake", referring to the spine on the death adder's tail.

Seven species are listed by ITIS,[1] though it remains unclear how many species this genus includes, with figures ranging from 4 to 15 species being quoted


Description

Death adders are very viper-like in appearance, having a short, robust body, triangular shaped heads and small subocular scales. They also have vertical pupils and many small scales on the top of the head. Their fangs are also longer and more mobile than for most other elapids, although still far from the size seen in some of the true vipers. Despite their name and appearance, they are not vipers at all. This is a case of convergent evolution.

They normally take 2–3 years to reach adult size. Females are generally slightly larger than the males. They can also be easily distinguished from other Australian snakes because of a small, worm like lure on the end of their tail, which is used to attract prey. Most have large bands around their bodies, though the color itself is variable, depending on their locality. Colors are usually black, grey or red and yellow, but also include brown and greenish-grey


Hunting

Unlike most snakes, death adders do not actively hunt, but rather lie in ambush and draw their prey to them. When hungry, death adders bury themselves amongst the substrate. This may be leaf litter, soil or sand, depending on their environment. The only part of themselves they expose are their head and their tail, both generally very well camouflaged. The end of the tail is used for caudal luring and when wiggled is easily mistaken for a grub or worm. An unsuspecting bird or mammal will eventually notice the 'easy lunch' and attempt to seize it. Only then will the death adder move, lashing out with the quickest strike of any snake in the world.[2] A death adder can go from a strike position, to strike and envenoming their prey, and back to strike position again, in less than 0.15 of a second.


Venom

Death adders can inject on average 40–100 mg of highly toxic venom with a bite. The LD50 of the venom was reported as 0.4–0.5 mg/kg subcutaneous and it is completely neurotoxic, containing neither haemotoxins nor myotoxins, unlike most venomous snakes.

A bite from a death adder can cause paralysis which seems minor at first but can cause death from a complete respiratory shutdown in six hours. Symptoms of envenomation can be reversed through the use of death adder antivenom, or using anticholinesterases, which break the synaptic blockade by making acetylcholine more available to the parasympathetic nervous system, thus mitigating the effects of the venom.

Before antivenom was introduced, it is reported that about 50% of death adder bites were fatal. Deaths are much rarer nowadays as the anti-venom is widely available and the progression of envenomation symptoms is slow.




Tuesday, 20 March 2012

Red Spitting Cobra

Description

This relatively medium-sized cobra attains lengths between 0.7 and 1.2 meters (2.3 and 3.9 ft),[1][2] but may grow to a maximum length of around 1.5 meters (4.9 ft) in very rare cases.[2][3] It is often thought of as an attractive species; it is usually bright salmon-red contrasted with a broad black throat band and subocular teardrop markings.[1] However, the colour of this species does have variation, which usually depends on where in Africa a particular specimen is found. For example, specimens from southern Kenya and northern Tanzania have an orange-red colour, with a broad, dark blue or black throat band. Some specimens may have two or three throat bands, but this is uncommon for specimens from East Africa. The ventral side is also reddish in colour, sometimes the throat area may be a creamy white. Specimens from other areas can be yellow, pinkish, pink-grey, pale red or steel grey. Most specimens will have a throat band, but it will fade or even sometimes disappear in larger adults. The true red specimens will become reddish-brown in colour as they age and grow in size.[2] The body of this snake is slightly depressed, tapered and moderately slender with a medium-length tail. It is slightly compressed dorsoventrally and subcylindrical posteriorly. The head is broad, flattened and slightly distinct from the neck. The canthus is distinct and the snout is rounded. The eyes are medium to large in size with round pupils. Dorsal scales are smooth and strongly oblique.


Scalation

Dorsal scales on the midbody are in 21–27, ventrals are in 197–228, and subcaudals are in 61–72 rows, subscales are paired, and the anal scale is single. There are seven upper labials, one upper labial enters the eye; two preoculars, three postoculars, and the lower labials are usually eight in number (range 7-9).

Distribution and habitat

The red spitting cobra is mainly found in East Africa, including Djibouti, Eritrea, Somalia, southern Egypt, northern and eastern Ethiopia, and northern Tanzania and northern Sudan. It is also widespread in the dry country of eastern and northern Kenya. It primarily inhabits dry savanna and semidesert areas of East Africa up to an elevation of about 1,200 metres (3,900 ft) above sea level. They can usually be found near water holes.


Behavior

Red spitting cobras are terrestrial, fast and alert snakes. Adults specimens of this species are nocturnal, while juveniles are more active during the day. Adults like to hide in termite mounds, old logs, holes, brush piles or any other ground cover during the day.[3] They are also known to be cannibalistic; this could be the reason juveniles and smaller specimens are diurnal while adults are nocturnal.[2]

When threatened, this cobra rears up and displays a typical cobra hood. It may also hiss loudly. If the intruder does not retreat, it may sprays jets of venom to the face of the intruder. Venom that gets into the eyes can cause burning pain and blindness. Even so, this snake seldom causes fatalities in humans.

Diet

This species has a wide range of prey, but they prefer amphibians such as toads and frogs, if and when they are available. However, they will prey on rodents, birds[1] and probably others snakes. They are known to raid chicken runs in the region.


Reproduction

The red spitting cobra is oviparous. The female will lay six to 15 eggs.

Venom

The venom of this species, like most spitting cobras, contains a mixture of neurotoxins and cytotoxins. Bite symptoms include slight pain around the wound and numbness of lips and tongue. Although it rarely causes human fatalities, survivors are usually disfigured.[1] The murine IP LD50 value for this snake is 2 mg/kg.[4]

In September 2011, a snake keeper from the Eastern Cape in South Africa died shortly after a red spitting cobra sprayed venom into his face whilst he and a friend were photographing the snake. Some of the venom was believed to have entered his nasal passages and led to anaphylactic shock. His being asthmatic is believed to have contributed to his fatal reaction.






Saturday, 4 February 2012

Farancia (Mud Snake)

Farancia is a genus of colubrid snakes. It consists of two species, one commonly referred to as the rainbow snake and the other commonly referred to as the mud snake. They are native to the eastern half of the United States.

Description

Farancia species can grow to a length of 30-54 inches. They are usually uniform dark brown or black with a brightly colored underside that is red or orange. Rainbow snakes exhibit red striping down their back.

Behaviour
The snakes of this genus are typically semi-aquatic. Living in the muddy edges of slow moving, permanent water sources. Their diet consists primarily of amphiumas, eels, and sirens. Breeding occurs in early spring, and eggs are laid in a burrow near the water in early summer. The clutch incubates between 8–12 weeks, and hatches in mid-autumn.




Species

    Farancia abacura - Texas, Arkansas, Louisiana, Mississippi, Alabama, Georgia, Florida, North and South Carolina, Virginia, Tennessee, Missouri, Illinois, and Kentucky.
        Eastern Mud Snake, Farancia abacura abacura (Holbrook, 1836)
        Western Mud Snake, Farancia abacura reinwardtii (Schlegel, 1837)
    Farancia erytrogramma - Louisiana, Mississippi, Alabama, Georgia, Florida, North and South Carolina, Virginia, and Maryland.
        Rainbow Snake, Farancia erytrogramma erytrogramma (Palisot de Beauvois, 1802)
        Florida Rainbow Snake, Farancia erytrogramma seminola (Neill, 1964)


Geographic range

The mud snake is found primarily in the southeastern United States, in the states of Texas, Arkansas, Oklahoma, Louisiana, Mississippi, Alabama, Georgia, Florida, North and South Carolina, Virginia, Tennessee, Missouri, Illinois, and Kentucky.



Cultural Significance

The mud snake is one of a few animals which may be the origin of the hoop snake myth. J.D. Wilson Writes:
“     Mud snakes are sometimes known as “hoop snakes” because of the myth that they will bite their own tail and roll after people.[1]     ”

The hoop snake myth has also been attributed to the Coachwhip snake.




Friday, 20 January 2012

Most Venomous Snakes in the World


 1.Taipan (Oxyuranus scutellatus): It is one of the most venomous and deadliest snakes in the world. There are three main sub-species of Taipan such as Papuan Taipan (Oxyuranus s. canni), Western or Inland Taipan (Oxyuranus Microlepidotus) or (Fierce Snake) and Common or Coastal Taipan (Oxyuranus Scutellatus). Taipans are found in Australia and New Guinea. Fierce snake or Inland Taipan is more toxic as compared to Papuan Taipan and Coastal Taipan. Inland Taipan is olive or brown in appearance, with uniformly black head or black marking on the head. Its habitat is grasslands and dry plains. Common or Coastal Taipan is dark or light brown in color with a paler shade on the sides and underside and lightly keeled scales. It is about 6 ft in length. It is found in the open woodlands and forests.

 2. Krait: This highly poisonous snake is found in Asia. It appears black or bluish-black in color with a white narrow cross-bands and a narrow head. Its average length is about 90cms. It is more active at night than during the day. It is 15 times more deadly than the common cobra. Its venom is a powerful neurotoxin, which causes the respiratory failure.
 
3. King cobra: It is world's largest venomous snake. Its average length is about 3.5 meters and it can be maximum 5.5 meters long. It appears uniformly brown, olive or green in color with black cross-bands. King cobra is commonly found in Southern China, Thailand, Philippines, South India and Malaysia Peninsula. Its venom is a neurotoxin type.
 
4. Russell's viper: Russell's viper is more commonly found in India, Sri Lanka, Malaysian Peninsula, Southern China, Sumatra, Java, Borneo and surrounding islands. It has a light brown body with three rows of black or brown splotches having white or yellow border. Its average length is about 1 meter. It is responsible for relatively more human deaths than any other types of venomous snake. While attacking, it coils tightly, hisses and strikes with such a high speed that its victim gets little chance to escape. Its venom is of hemotoxin type, which is a powerful coagulant, causing damage to blood cells and tissues.
  
5. Black Mamba: It is Africa's most feared venomous snake. It is found in Africa's open woodlands and African savannas. It is highly toxic and notoriously aggressive. Its venom is a powerful neurotoxin. It appears uniformly black or brown. Its average length is about 4.3 meters. Its mouth has a black internal lining. It is known as world's fastest land snake with the top speed of 16-19 km/hr.

 6.Tiger snake: It is olive or dark brown in color with olive or yellowish belly and cross-bands. Its subspecies are found in Victoria and Tasmania and it is uniformly black. Its average length is about 1.2 to 1.8 meters. It is one of the most venomous snakes found in Australia. It is also found in New Guinea, Tasmania and Bass Strait Islands. Its venom is a potent neurotoxin that affects the central nervous system. It produces venom in high quantities, with an average yield of about 35 mg to 180 mg.
  
7. Western Brown Snake (Pseudonaja nuchalis): It is found in the grasslands, forests, deserts and gravelly plains. It is a native of Australia. It has a narrow black head and black neck. It may be black or light brown in color with narrow dark crossbars or a series of lighter bands around the body. It is about 1.5 meters in length. Its venom is neurotoxic.

Monday, 17 October 2011

Chrysopelea ornata:-flying snake or golden tree snake

Chrysopelea ornata is a colubrid snake found in South and Southeast Asia. It is, along with the other species in its genus Chrysopelea, very unusual in that it is capable of a type of gliding flight. It is also rear-fanged. Currently, three subspecies are recognized, including the typical form described here. The snake's striking looks and capability of gliding make it a popular choice for captivity.

Description

Chrysopelea ornata is usually green in color, with black cross-hatching and yellow or gold colored accents. The body, though slender, is far less so than in other tree snakes. It has a flattened head with constricted neck, a blunt nose and large eyes with round pupils.[1]

The lateral, sharp and pronounced keeled condition of the ventrals in association with the normal, not enlarged, vertebral row of scales distinguish this snake. The snakes rarely exceed 40 inches in length, the smallest being measured at 115mm[4] and the largest being 1,360 mm (4 ft 51/2 in) long. The tail is about one-fourth of the total length.[1]

Chrysopelea ornata has two major colour forms, which are largely determined by geographic locality, and their descriptions are given below:[1]

    In Sri Lanka and southern extent of its Indian range, the snake is primarily greenish yellow or pale green. Each scale has a black mesial streak or spot, and is more or less edged with black. The snake also has dark crossbars at intervals. A series of large, flower-shaped, reddish or orange vertebral spots may be present or absent. Ventrals greenish, outside the keel edged with black or spotted. Head black with vellow crossbars and spots. The flower-shaped spots are commoner in Sri Lanka than in south India.

    The second colour variety occurs Southeast Asia lacks the reddish vertebral spots, and has less prominent black crossbars.


Venom
This species is considered mildly venomous, with no confirmed cases of medically significant envenomation.

Red-spotted form of Chrysopelea ornata from North Bengal, India

Geographic range

India, Sri Lanka, Myanmar, Thailand, western Malaysia, Laos, Cambodia, Vietnam, China (Hong Kong, Hainan, Yunnan), Indonesia (Sumatra, Java, Borneo, Sulawesi), and the Philippines.

In India Chrysopelea ornata ranges from the Western Ghats, up to the Dangs, Katernia Ghat in Uttar Pradesh, North Bihar, northern West Bengal[1] eastwards to Arunachal Pradesh.[6] It is also found in the forests of the Andaman islands.[1]


Chrysopelea ornata climbing up prior to launching itself into the air
Behaviour

Chrysopelea ornata is diurnal and arboreal. The snake's gliding ability, while not as impressive as that of the paradise flying snake (C. paradisi), still makes it capable of moving from tree to tree with relative ease. These snakes are excellent climbers, being able move across even the smallest of branches and even straight up trees with few branches by using the edges of rough bark. They are frequently seen moving up a coconut palm, or up vertical rock faces in graceful curves, gripping the somewhat uneven surfaces with their scales. They tend to be nervous, fast-moving snakes, and will attempt to flee if disturbed, but will not generally hesitate to bite if handled. They are mildly venomous, but the venom is not considered to be dangerous to humans.[4] It is intended to assist in subduing fast moving, arboreal prey. C. ornata takes small arboreal prey, such as lizards, bats and small rodents.[7] It might also feed on bird eggs and insects. Also it is reported to take snakes occasionally, and to avoid frogs, though frogs are also reported being eaten. The snake stalks or pursues the prey and seizes it by the neck, which is duly crushed in its strong jaws.[4]


Flight
Chrysopelea ornata, like others of its genus, glides or parachutes. This is presumably done to cover distances faster, to escape predators, to catch prey, or to move around in forests. Flying snakes usually parachute from tree to tree, but sometimes launch themselves from trees onto the ground. They have been known to cross as much as 100m.[5]

It does this by climbing up to a height, which it does easily by virtue of its keeled belly scales, and then launching itself into mid-air. The snake contracts its ventral surface inwards to form a U-shaped concave depression along the entire length of their bodies, holding the outer edges of the ventral scales rigid. This concave surface acts like a parachute, and increases air resistance, allowing the snake to glide forward with the thrust of its launch. The snake undulates through the air, in a swimming-like motion. It holds the tail rigidly upwards, and by twisting the tail from side to side, it attains balance. This motion allows it to propel forward, landing clumsily at the end of its flight.[5]


Head of C. ornata with brilliantly coloured tongue exposed
Reproduction
Breeding habits are little known. The snake is oviparous[6] and six to twelve elongated eggs[1] are laid. Gravid females have been obtained in May and June and hatchlings in June. In Bangkok, according to Smith, mating takes place in June. Hatchlings measure 114–152 mm (4 1/2 to 6 in) in length, while the smallest gravid female recorded was 1,093 mm (3 ft 7 in) in length.[1]


Thursday, 13 October 2011

Deadly Black mamba

black mamba
The black mamba (Dendroaspis polylepis) is the longest venomous snake in Africa, averaging around 2.5 meters (8.2 ft), and sometimes growing up to 4.3 meters (14 ft). Its name is derived from the black colouration inside the mouth rather than the actual colour of the skin which varies from dull yellowish-green to a gun-metal grey. It is the fastest snake in the world, capable of moving at 4.32 to 5.4 metres per second (16–20 km/h, 10–12 mph).

Description
The black mamba's back skin colour is olive, brownish, gray, or sometimes khaki.[5] The adult snake's length is on average 2.5 meters (8.2 ft),[1] but some specimens have reached lengths of 4.3 to 4.5 meters (14 to 15 ft).[5] Black mambas weigh about 1.6 kilograms (3.5 lb).[1] on average. The species is the second longest venomous snake in the world, exceeded in length only by the king cobra.[5] The snake has an average life span of 11 years in the wild.[1]

Habitat
The black mamba has adapted to a variety of climates ranging from savanna, woodlands, rocky slopes, dense forests and even humid swamps.[6] The grassland and savanna woodland/shrubs that extend through central, eastern and southern Africa are the black mamba's typical habitat.[6] The black mamba prefers more arid environments such as light woodland, rocky outcrops, and semi-arid dry bush country.

Behaviour

The black mamba uses its speed to escape threats, not to hunt prey.[1] It is known to be capable of reaching speeds of around 20 kilometers per hour (12 mph), traveling with up to a third of its body raised off the ground.[1] Over long distances the black mamba can travel 11 to 19 kilometers per hour (6.8 to 12 mph), but in short bursts it can reach a speed of 16 to 20 kilometers per hour (9.9 to 12 mph),or even 23 kilometers per hour (14 mph) [8] making it the fastest land snake.[9] It is shy and secretive; it always seeks to escape when a confrontation occurs.[1] If a black mamba is cornered it mimics a cobra by spreading a neck-flap, exposing its black mouth, and hissing.[1] If this endeavor to scare away the attacker fails, the black mamba may strike repeatedly.[1] The black mamba is a diurnal snake. Although its scientific name seems to be indicative of tree climbing, the black mamba is rarely an arboreal snake.[9] These snakes retreat when threatened by predators.


Venom

The venom of the black mamba consists mainly of potent neurotoxins[10]. With a LD50 of 0.25 mg/kg—0.32 mg/kg, the black mamba's venom is virulently toxic.[11] Some of the components of the venom have a much more toxic LD50 value than the venom as a whole, for example α-dendrotoxin (or "Toxin 1") and γ-dendrotoxin (or "Toxin 7") had subcutaneous LD50 values of 0.09 µg and 0.12 µg per gram of white mice, respectively.[12] Although only 10 to 15 mg[13] is deadly to a human adult, its bite delivers about 100–120 mg of venom on average[13], but they can deliver up to 400 mg of venom in a single bite[13]. It is reported that before the antivenom was widely available, the mortality rate from a bite was 100%.[14][15][16][17][1][18] Black mamba bites can potentially kill a human within 20 minutes or less[19][20][13][12] depending on the nature of the bite and the area bitten, but death usually occurs after 30–60 minutes on average, sometimes even taking up to three hours. British wildlife enthusiast Nathan Layton was bitten near Hoedspruit by a juvenile black mamba and died less than 30 minutes after being bitten.[21] The fatality duration and rate depend on various factors, such as the health, size, age, psychological state of the human, the penetration of one or both fangs from the snake, amount of venom injected, location of the bite, and proximity to major blood vessels.[1] The health of the snake and the interval since it last used its venom mechanism is also important. Presently, there is a polyvalent antivenom produced by SAIMR (South African Institute for Medical Research) to treat all black mamba bites from different localities.[18]

If bitten, common symptoms for which to watch are rapid onset of dizziness, coughing or difficulty breathing, and erratic heartbeat.[18] In extreme cases, when the victim has received a large amount of venom, death can result within minutes[1] from respiratory or cardiac arrest.[18] This is especially true if the victim is bitten in the face or chest area, as a black mamba can rear up around one-third of its body from the ground which puts it at about four feet high. When warding off a threat, the black mamba delivers multiple strikes, injecting large amounts of virulently toxic venom with each strike, often landing bites on the body or head, unlike other snakes. Also, the black mamba's venom has been known to cause paralysis.[18] Death is due to suffocation resulting from paralysis of the respiratory muscles.[18]

Many herpetologists, including South African-born herpetologist Austin Stevens, regard the black mamba as one of, if not the most dangerous and feared snakes in the world due to various factors including the toxicity and high yield of its venom, its high level of aggression, its speed, agility, size, and other factors.[22][12] Nevertheless, attacks on humans by black mambas are rare, as the snakes usually avoid confrontation with humans and their occurrence in highly-populated areas is not very common compared with some other species.
 
 Toxin

Mamba venom is made up mostly of dendrotoxins (dendrotoxin-k - "Toxin K"[23], dendrotoxin-1 - "Toxin 1"[24], dendrotoxin-3 - "Toxin 3"[25], dendrotoxin-7 - "Toxin 7"[25]), and calciseptine[26]. The dendrotoxins disrupt the exogenous process of muscle contraction by means of the sodium potassium pump. Toxin K is a selective blocker of voltage-gated potassium channels[27], Toxin 1 inhibits the K+ channels at the pre and post-synaptic level in the intestinal smooth muscle. It also inhibits Ca2+-sensitive K+ channels from rat skeletal muscle‚ incorporated into planar bilayers (Kd = 90 nM in 50 mM KCl)[28], Toxin 3 inhibits M4 receptors, while Toxin 7 inhibits M1 receptors.[25] The calciseptine is a 60 amino acid peptide which acts as a smooth muscle relaxant and an inhibitor of cardiac contractions. It blocks K+ induced contraction in aortic smooth muscle and it blocks spontaneous contraction of uterine muscle and portal vein.[29][13] The venom is highly specific and virulently toxic. In an experiment, the death time of a mouse after subcutaneous injection of some toxins studied is around 7 minutes. However, a black mamba venom can kill a mouse after 4.5 minutes.[12]


 Hunting and prey

As stated, the black mamba is diurnal. It is an ambush predator that waits for prey to get close.[8] If the prey attempts to escape, the black mamba will follow up its initial bite with a series of strikes.[8] When hunting, the black mamba has been known to raise a large portion of its body off the ground.[8] The black mamba will release larger prey after biting it, but smaller prey, such as birds or rats, are held onto until the prey's muscles stop moving.[8] They have been known to prey on bushbabies, bats, and small chickens.

black mamba attacking

Wednesday, 12 October 2011

KING COBRA

king cobra
The king cobra (Ophiophagus hannah) is the world's longest venomous snake, with a length up to 5.6 m (18.5 ft).[1] This species, which preys chiefly on other snakes, is found predominantly in forests from India through Southeast Asia to the Philippines and Indonesia. Despite the word "cobra" in its name, this snake is not a member of Naja ("true cobras") but belongs to its own genus.

Identification

The king cobra is the sole member of genus Ophiophagus, while most other cobras are members of the genus Naja. They can be distinguished from other cobras by size and hood marks. King cobras are generally larger than other cobras, and the stripe on the neck is like the symbol "^" instead of a double or single eye(s) shape that may be seen in most of the other Asian cobras. A foolproof method of identification is if on the head, clearly visible, is the presence of a pair of large scales known as occipitals, at the back of the top of the head. These are behind the usual "nine-plate" arrangement typical of colubrids and elapids, and are unique to the king cobra.


Habitat

The king cobra is distributed across South Asia, Southeast Asia, and the southern areas of East Asia (southern China) where it is not common. It lives in dense highland forests,[1][4] preferring areas dotted with lakes and streams. King cobra populations have dropped in some areas of its range because of the destruction of forests. It is listed as an Appendix II Animal within CITES.
[5]

Behaviour

King cobras, like other snakes, receive chemical information ("smell") via their forked tongues, which pick up scent particles and transfer them to a special sensory receptor (Jacobson's organ) located in the roof of its mouth.[1] When the scent of a meal is detected, the snake flicks its tongue to gauge the prey's location (the twin forks of the tongue acting in stereo); it also uses its keen eyesight (king cobras are able to detect moving prey almost 100 m [300 feet] away), intelligence[6] and sensitivity to earth-borne vibration to track its prey.[7] Following envenomation, the king cobra will begin to swallow its struggling prey while its toxins begin the digestion of its victim. King cobras, like all snakes, have flexible jaws. The jaw bones are connected by pliable ligaments, enabling the lower jaw bones to move independently, enabling the King cobra to swallow its prey whole. The expansion of the jaw enables the snake to swallow prey much larger than its head.[1]

King cobras are able to hunt at all times of day, although it is rarely seen at night, leading most herpetologists to classify it as a diurnal species.


South Indian king cobra

Defense

Although the king cobra usually avoids confrontation with humans, it can be aggressive if provoked.[9] If threatened, it rears up the anterior portion of its body when extending the neck, showing the fangs and hissing loudly.[10] It can be easily irritated by closely approaching objects or sudden movements. The snake strikes rapidly and the attack range can be as far as 2 meters. It is also known to advance to the enemy with a certain distance due to its far strike range where people can easily misjudge the safe zone. The king cobra can deliver multiple bites in a single attack but adults are known to bite and hold on.[11] In spite of being a highly dangerous snake, it prefers to escape first unless it is cornered or provoked.[9] Since this species is secretive and tends to inhabit less-populated forested regions and dense jungle, it is rarely encountered.

If a king cobra encounters a natural predator, such as the mongoose, which has resistance to the neurotoxins,[12] the snake generally tries to flee. If unable to do so, it forms the distinctive cobra hood and emits a hiss, sometimes with feigned closed-mouth strikes. These efforts usually prove to be very effective, especially since it is more dangerous than other mongoose prey, as well as being much too large for the small mammal to kill with ease.


king cobra snake attack
 Venom

The venom of the king cobra consists primarily of neurotoxins, but it also contains cardiotoxic and some other compounds.[8] Toxic constituents are mainly proteins and polypeptides.[14]

During a bite, venom is forced through the snake's 1.25 to 1.5 centimeters (0.49 to 0.59 in) fangs into the wound, and the toxins begin to attack the victim's central nervous system. Symptoms may include severe pain, blurred vision, vertigo, drowsiness, and paralysis. Envenomation progresses to cardiovascular collapse, and the victim falls into a coma. Death soon follows due to respiratory failure. Moreover, king cobra envenomation is clinically known to cause renal failure.[15]

A 1990 book makes a passing statement of a LD50 of 0.34 mg/kg for this species[16], however this value is inconsistent with most toxicological studies.[17][18][19] For example, a recent study lists the LD50 of the king cobra venom as 1.6 mg/kg – 1.8 mg/kg[20], making it's venom one of the least potent among the elapids.[15] This value is further backed up by another toxicological study which lists the LD50 of the king cobra at 1.7 mg/kg.[21] A similar mean LD50 value of 1.93 mg/kg was obtained from the venom of five wild caught king cobras in Southeast Asia (Meier et al 1995).[22]

This species is capable of delivering a large quantity of venom, injecting a dose anywhere from 200-500 milligrams on average, but it can potentially deliver much more than 500 mg.[10][16][23] Though the venom is weak compared to most other elapids,[15] it can still deliver a bite which can potentially kill a human due to the massive amount of venom it delivers in a single bite. Mortality can vary sharply with amount of venom involved, most bites involve nonfatal amounts.[24] According to a research report from the University of Adelaide Department of Toxinology, an untreated bite has a mortality rate of 50-60%[25]

There are two types of antivenom made specifically to treat king cobra envenomations. The Red Cross in Thailand manufactures one, and the Central Research Institute in India manufactures the other; however, both are made in small quantities and are not widely available.[26] Ohanin, a protein component of the venom, causes hypolocomotion and hyperalgesia in mammals.[27] Other components have cardiotoxic,[28] cytotoxic and neurotoxic effects.[29] In Thailand, a concoction of alcohol and the ground root of turmeric is ingested, which has been clinically shown to create a strong resilience against the venom of the king cobra, and other snakes with neurotoxic venom.[30]

The haditoxin in the king cobra venom was discovered by Singaporean scientists to be structurally unique and can have unique pharmacological properties.[31] Biochemical studies confirmed that it existed as a non-covalent dimer species in solution. Its structural similarity to short-chain α-neurotoxins and κ-neurotoxins notwithstanding, haditoxin exhibited unique blockade of α7-nAChRs (IC50 180 nM), which is recognized by neither short-chain α-neurotoxins nor κ-neurotoxins.[14]


Reproduction

The king cobra is unusual among snakes in that the female king cobra is a very dedicated parent. She makes a nest for her eggs, scraping up leaves and other debris into a mound in which to deposit them, and remains in the nest until the young hatch.

A female usually deposits 20 to 40 eggs into the mound, which acts as an incubator. She stays with the eggs and guards the mound tenaciously, rearing up into a threat display if any large animal gets too close,[32] for roughly 60 to 90 days.

Inside the mound the eggs are incubated at a steady 28 °C (82 °F). When the eggs start to hatch, instinct causes the female to leave the nest and find prey to eat so she does not eat her young.[33] The baby king cobras, with an average length of 45 to 55 centimeters (18 to 22 in), have venom which is as potent as that of the adults. They may be brightly marked but these colours often fade as they mature. They are alert and nervous, being highly aggressive if disturbed.

king cobra eating snake
Diet
The king cobra's genus name, Ophiophagus, means "snake-eater", and its diet consists primarily of other snakes, including ratsnakes, small pythons and even other venomous snakes (smaller members of its own species, true cobras (of the genus Naja), and even the much more venomous members of the krait family.[8][13] When food is scarce, they may also feed on other small vertebrates, such as lizards, birds, and rodents. In some cases, the cobra may "constrict" its prey, such as birds and larger rodents, using its muscular body, though this is uncommon.[1][13] After a large meal, the snake may live for many months without another one because of its slow metabolic rate.[1] The king cobra's most common meal is the ratsnake; pursuit of this species often brings king cobras close to human settlements.

Monday, 26 September 2011

CORN SNAKES

The Corn Snake (Pantherophis guttatus), or Red Rat Snake, is a North American species of Rat Snake that subdues its small prey by constriction.[1] The name "Corn Snake" is a holdover from the days when southern farmers stored harvested ears of corn in a wood frame or log building called a crib. Rats and mice came to the corn crib to feed on the corn, and Corn Snakes came to feed on the rodents.[2] The Oxford English Dictionary cites this usage as far back as 1676. Corn Snakes are found throughout the southeastern and central United States. Their docile nature, reluctance to bite, moderate adult size 3.9–5.9 feet (1.2–1.8 m), attractive pattern, and comparatively simple care make them popular pet snakes. In the wild, they usually live around 6–8 years, but in captivity can live to be up to 23 years old.

Natural habitat
Wild Corn Snakes prefer habitats such as overgrown fields, forest openings, trees, palmetto flatwoods and abandoned or seldom-used buildings and farms, from sea level to as high as 6,000 feet. Typically, these snakes remain on the ground, but can ascend trees, cliffs and other elevated surfaces.[8] They can be found in the southeastern United States ranging from New Jersey to the Florida keys and as far west as Texas.

In colder regions, snakes hibernate during winter. However, in the more temperate climate along the coast they shelter in rock crevices and logs during cold weather, and come out on warm days to soak up the heat of the sun, a process known as brumation.[9] During cold weather, snakes are less active and therefore hunt less.


A Corn Snake swallowing a small rat
Diet
Corn Snakes have a diet primarily consisting of rodents, mostly mice and rats. Prey is killed by constriction. They are proficient climbers and may scale trees in search of birds and bats although they prefer to be on ground level. As litters of infant mice are difficult to find in nature, many neonate Corn Snakes are known to eat small lizards as their first meals, and anoles are the preferred choice.[10] Some individuals retain these dietary tendencies well into adulthood.

Captive Corn Snakes are usually fed by their owners on a diet of commercially available rodents, predominantly mice, while younger and smaller specimens may eat live or dead rat or mouse pups of various sizes. Frozen "pinkies" (baby mice) that have been warmed in hot tap water for 10-15 minutes are ideal for baby corn snakes. As the snake grows, the size of the prey grows.


 
Baby Corn Snakes hatching from their eggs
Reproduction
Corn Snakes usually breed shortly after the winter cooling. The male courts the female primarily with tactile and chemical cues, then everts one of his hemipenes, inserts it into the female, and ejaculates his sperm. If the female is ovulating, the eggs will be fertilized, and she will begin sequestering nutrients into the eggs, then secreting a shell.

Egg-laying occurs slightly more than a month after mating, with 12–24 eggs deposited into a warm, moist, hidden location. Once laid the adult snake abandons the eggs and does not return to them. The eggs are oblong with a leathery, flexible shell. Approximately 10 weeks after laying, the young snakes use a specialized scale called an egg tooth to slice slits in the egg shell, from which they emerge at about 5 inches in length.


Anerythristic A Corn Snake


Amelanistic Stripe Corn Snake

"Opal" phase Corn Snake (Pantherophis guttatus)

MILK SNEKES


The milk snake or milksnake (Lampropeltis triangulum; French: Couleuvre tachetée; Spanish: Culebra-real coralillo, Lithuanian: Pieninė gyvatė)[1] is a species of king snake. There are 25 subspecies among the milk snakes, including the commonly named scarlet kingsnake (L. t. elapsoides).[1] The subspecies have strikingly different appearance, and many of them have their own common names. Some authorities suggest that this species may be split into several separate species
red milk snake Lampropeltis triangulum syspila

Description
Milk snakes grow 20 to 60 inches (51 to 150 cm) long.[1] They have smooth and shiny scales and their typical color pattern is alternating bands of red-black-yellow or white-black-red. [1] However, red blotches instead of bands are seen in some populations.[1] Some milk snakes have a striking resemblance to coral snakes and this mimicry (known as Batesian mimicry) likely scares away potential predators. While both milk snakes and coral snakes possess transverse bands of red, black and yellow, a common mnemonic can be used to properly distinguish between the deadly coral snake and the harmless milk snake:

        "Red on yellow will kill a fellow, but red on black is a friend of Jack."
        "Red on yellow, deadly fellow; Red on black, venom lack."
        " Red and yellow will kill you fellow; Red and black is friend Jack."
        "Red on yellow, kill a fellow. Red on black, you're alright Jack."
        "Red next to black is a friend of Jack; red next to yellow will kill a fellow."
        "Red to yellow, kill a fellow. Red to black, venom lack."
        "If red touches black, you're okay Jack; if red touches yellow, you're a dead fellow."
        "Red next to black, you can pat him on the back; red next to yellow, he can kill a fellow."
        "Red next to black, venom I lack; red next to yellow, run away fellow."
        "Red and black, friend of Jack; red and yellow kill a fellow."
        "Red touches yellow, Not a nice fellow; if red touches black, good friend of jack."
        "Red touch yellow, kill a fellow; red touch black, you're okay Jack."

juvenile Eastern milk snake

However, the Eastern milk snake (L. t. triangulum) does not resemble a coral snake; instead it tends to have similar markings to that of several other snakes, particularly the fox snake, scarlet snake and most importantly, the Massassauga rattlesnake. Milk, fox, and scarlet snakes are killed because of a resemblance to the venomous rattlesnake. Juvenile milk snakes, which are more reddish than adults, are often killed because they are mistaken for copperheads. There is enough distinction among the five to make the Eastern milk snake fairly easy to identify. Eastern milk snakes also have a light colored v-shaped or y-shaped patch on their neck. One subspecies is melanistic (almost all black).


juvenile Eastern milk snake

Geographic range

They are distributed from southeastern Canada, through most of the continental United States, to Central America, down to western Ecuador and northern Venezuela of northern South America.


Habitat

Across the wide range of this species, habitat varies. Typically, milk snakes live in forested regions, however, in some regions they can be located in open prairies. In various parts across its distribution, milk snakes often abide in rocky slopes.[1]


Behavior
Milk snake activity is mostly nocturnal. They are primarily terrestrial, except the scarlet kingsnake which is known to take shelter under the bark of standing dead trees. They also try to blend in with dead leaves.


Diet

Young milk snakes typically eat slugs, insects, crickets, and earthworms.[3] Adult diet frequently includes lizards (especially skinks), and small mammals.[1] They are also known to eat birds and their eggs, frogs, fish, and other snakes.[3]

Milk snakes are much more opportunistic eaters than the fox snake or corn snake. They have been known to consume a variety of animals including rodents, eggs, birds, reptiles, amphibians, and invertebrates. Nevertheless the diet of an adult milk snake still primarily consists of rodents. They are nocturnal eaters and are often found during the day in old barns and under wood.

An early myth about milk snakes is that they suck cow udders to get the milk. The myth is entirely false, and is discredited by the fact that the milk snake does not have the physical capabilities to suck milk out of a cow. Milk snakes are, however, frequently found in and around barns, making use of their cool and dark environments, and for the easily accessed populations of rodents to feed on. This proximity to barns, and therefore cows, probably gave rise to the myth


Mexican Milk Snake, L. t. annulata  
Reproduction

Milk snakes are oviparous, laying an average of about 10 eggs per clutch, although that number may vary by region.[1] The milk snake mates from early May[3] to late June. In June and July, the female lays three to twenty-four eggs beneath logs, boards, rocks, and rotting vegetation.[3] The eggs incubate for approximately two months, and hatch around August or September.[3] Milk snakes typically live around twelve years.


Conservation status
The milk snake is not listed by the IUCN (a wildlife conservation union), but in some areas, they may face significant pressure due to pet trade collection.[1] Because this species' high value in the pet trade, many subspecies are now being bred in captivity for sale.

Saturday, 17 September 2011

Eastern Coral Snake

The coral snakes are a large group of elapid snakes that can be subdivided into two distinct groups, Old World coral snakes and New World coral snakes. There are 11 species of Old World coral snake in one genus (Calliophis), and over 65 recognized species of New World coral snakes in three genera (Leptomicrurus, Micruroides, and Micrurus).
Coral snake (Micrurus sp.)





North American coloration patterns

Coral snakes are most notable for their red, yellow/white, and black colored banding. (However, several nonvenomous species have similar coloration, including the scarlet snake, genus Cemophora, some of the kingsnakes and milk snakes, genus Lampropeltis, and the shovelnose snakes, genus Chionactis.) In some regions, the order of the bands distinguishes between the non-venomous mimics and the venomous coral snakes, inspiring some folk rhymes — "Red on yellow, kill a fellow; "Red on black, friend of Jack"; and "Red into black, venom lack; red into yellow, kill a fellow." However, this reliably applies only to coral snakes native to North America: Micrurus fulvius (Eastern or common coral snake), Micrurus tener (Texas coral snake), and Micruroides euryxanthus (Arizona coral snake), found in the southern and western United States. Coral snakes found in other parts of the world can have distinctly different patterns, have red bands touching black bands, have only pink and blue banding, or have no banding at all.

Most species of coral snake are small in size. North American species average around 3 feet (91 cm) in length, but specimens of up to 5 feet (150 cm) or slightly larger have been reported. Aquatic species have flattened tails acting as a fin, aiding in swimming.


Texas Coral Snake, Micrurus tener


Behavior

Coral snakes vary widely in their behavior, but most are very elusive, fossorial snakes which spend the vast majority of their time buried beneath the ground or in the leaf litter of a rainforest floor, only coming to the surface while raining or during breeding season. Some species, like Micrurus surinamensis are almost entirely aquatic and spend most of their lives in slow-moving bodies of water that have dense vegetation.

Like all elapid snakes, coral snakes use a pair of small fangs fixed in the front of their top jaw to deliver their venom. They feed on smaller snakes, lizards, frogs, and nestling birds and rodents etc. The venom takes time to fully take effect.[1]

Coral snakes have a tendency to hold on to a victim when biting, unlike vipers which have retractable fangs and tend to prefer to strike and let go immediately. Coral snakes are not aggressive or prone to biting however, and account for less than one percent of the number of snake bites each year in the United States. Most coral snake bites in the United States are legitimate occurring because of accidental contact with the snake while engaged in an outdoor activity such as gardening.


Coral snake showing typically reclusive behavior of hiding under rotting wood. This one was over 30 inches long, but less than an inch across.

Distribution

New World coral snakes exist in the southern range of many temperate U.S. states.

Coral Snakes are found in scattered localities in the southern Coastal Plain from North Carolina to Louisiana, including all of Florida. They can be found in pine and scrub oak sandhills habitats in parts of this range but sometimes inhabit hardwood areas and pine flatwoods that undergo seasonal flooding.[2]

There is controversy about the classification of the very similar Texas coral snake as a separate species. Its habitat, in Texas, Louisiana, and Arkansas, is separated from the eastern habitat by the Mississippi River. The coral snake population is most dense in the southeast United States, but coral snakes have been spotted as far north as Kentucky.[3]

The Arizona coral snake, clearly a separate species and genus, is found in central and southern Arizona, extreme southwestern New Mexico and southward to Sinaloa in western Mexico. It occupies arid and semiarid regions in many different habitat types including thornscrub, desert-scrub, woodland, grassland and farmland. It is found in the plains and lower mountain slopes from sea level to 5800 feet (1768 m); often found in rocky areas.



Danger to humans
New World coral snakes possess one of the most potent venoms of any North American snake. Most venomous snakes must inject between 75–100 mg of venom to be fatal.[5] However, relatively few bites are recorded due to their reclusive nature and the fact they generally inhabit sparsely populated areas. According to the American National Institutes of Health, there are an average of 15-25 coral snake bites in the United States each year.[6]

When confronted by humans, coral snakes will almost always attempt to flee, and bite only as a last resort. In addition, coral snakes have short fangs (proteroglyph dentition) that cannot penetrate thick leather clothing. Any skin penetration however, is a medical emergency that requires immediate attention. Coral snakes have a powerful neurotoxin that paralyzes the breathing muscles; mechanical or artificial respiration, along with large doses of antivenin, are often required to save a victim's life. There is usually only mild pain associated with a bite, but respiratory failure can occur within hours.

The bite of a coral snake may soon become increasingly more dangerous, ironically because of the relatively few bites each year. Production of coral snake antivenin in the United States has ceased because it is not profitable. According to Pfizer, the owner of the company that used to make Coralmyn, it would take over $5–$10 million to put toward researching a new synthetic antivenom. The cost was just too large for the small number of cases presented each year. The current antivenin stock expired in 2010, after two consecutive expiration date extensions approved by the U.S. Food and Drug Administration. Foreign pharmaceutical manufacturers have produced other coral snake antivenins, but the costs associated with licensing them in the United States have stalled availability (see above).[7] Instituto Bioclon is developing a coral snake antivenin.


Range: The Eastern Coral Snake occurs throughout Florida, south into the Upper Florida Keys. Outside of Florida, it is found north to southeastern North Carolina and west to eastern Texas and northeastern Mexico.

Habitat: This species occupies a variety of habitats, from dry, well–drained flatwoods and scrub areas to low, wet hammocks and the borders of swamps. They are quite secretive and are usually found under debris and in the ground, but occasionally they are found in the open, and have even been seen climbing the trunks of live oaks. Good numbers of them are turned up when pine flatwoods are bulldozed, particularly in southern Florida.


Friday, 16 September 2011

Rattlesnake:-

Crotalus cerastes
Rattlesnakes are a group of venomous snakes of the genera Crotalus and Sistrurus[1] of the subfamily Crotalinae ("pit vipers"). There are 32 known species of rattlesnake, with between 65-70 subspecies.[2], all of which are native to the Americas - ranging from southern Alberta, and southern British Columbia Canada to Central Argentina.

Rattlesnakes are predators who live in a wide array of habitats, hunting small animals such as birds and rodents. They kill their prey with a venomous bite, rather than by constricting. All rattlesnakes possess a set of fangs with which they inject large quantities of hemotoxic venom. The venom travels through the bloodstream, destroying tissue and causing swelling, internal bleeding, and intense pain. Some species, such as the Mojave Rattlesnake, additionally possess a neurotoxic component in their venom that causes paralysis and other nervous symptoms.

The threat of envenomation, advertised with the shaking of the rattle, deters many predators. However, rattlesnakes fall prey to hawks, weasels, king snakes, and a variety of other species. Rattlesnakes are heavily preyed upon as neonates, while they are still weak and mentally immature. Very large numbers of rattlesnakes are killed by humans. Rattlesnake populations in many areas are severely threatened by habitat destruction, poaching, and extermination campaigns.

Rattlesnake bites are the leading cause of snakebite injuries in North America, and cause approximately 82% of fatalities. However, rattlesnakes rarely bite unless provoked or threatened; and if treated promptly, the bites are rarely fatal.


Range and habitat

Rattlesnakes are native to the Americas, living in diverse habitats from Southwestern Canada to Central Argentina. The large majority of species live in the American Southwest and Mexico. Four species may be found east of the Mississippi river, and two in South America. In the United States, the state with the most forms of rattlesnakes is Arizona, with seventeen species and subspecies.[5][6]

Rattlesnakes are found in almost every type of habitat that is capable of supporting terrestrial ectothermic vertebrates; but individual species can have extremely specific habitat requirements, only able to live within certain plant associations in a narrow range of altitudes. Most species live near open, rocky areas. Rocks offer them cover from predators, plentiful prey (e.g. rodents, lizard, insects, etc. that live amidst the rocks), and open basking areas. However, rattlesnakes can also be found in a wide variety of other habitats including prairies, marshes, deserts, and forests.[7] Rattlesnakes prefer a temperature range between 80 and 90°F (26-32°C), but can survive temperatures below freezing, recovering from brief exposure to temperatures as low as 4°F, and surviving for several days in temperatures as low as 37°F.[8]
Evidence has been collected to show the most probable ancestral area of rattlesnakes is the Sierra Madre Occidental region in Mexico. This same study found the most probable vegetation or habitat of the ancestral area to be pine-oak forests



Prey

Rattlesnakes consume mice, rats, small birds and other small animals[9], playing an important ecological role by limiting the size of rodent populations, which prevents crop damage and stabilizes ecosystems.[10]

Rattlesnakes lie in wait for their prey, or hunt for it in holes.[11] The prey are killed quickly with a venomous bite as opposed to constricting. If the bitten prey moves away before dying, the rattlesnake can follow it by its scent.[12][13] When it locates the fallen prey, it checks for signs of life by prodding with its snout, flicking its tongue, and using its sense of smell. Once the prey has become incapacitated, the rattlesnake locates its head by odors emitted from the mouth. The prey is then ingested head-first, which allows wings and limbs to fold at the joints in a manner which minimizes the girth of the meal.[14] The gastric fluids of rattlesnakes are extremely powerful, allowing for the digestion of bone as well as flesh. Optimal digestion occurs when the snake maintains a body temperature of between 80 and 85°F (25-29°C). If the prey is small, the rattlesnake will often continue hunting. If it was an adequate meal, the snake will find a warm, safe location in which to coil up and rest until the prey is digested.[15]

Rattlesnakes are believed to require at least their own body weight in water annually in order to remain hydrated. The method in which they drink depends on the water source. In larger bodies of water (streams, ponds, etc.) they will submerge their head and ingest water by opening and closing their jaw, which sucks in water. If drinking dew, or drinking from small puddles, they will sip the liquid either by capillary action or by flattening and flooding the lower jaw.


Venom

Most species of rattlesnakes have hemotoxic venom, destroying tissue, causing necrosis and coagulopathy (disrupted blood clotting).[30] In the U.S., some varieties of the Mojave rattlesnake (C. scutulatus) have a presynaptic neurotoxic venom component known as Mojave Type A toxin, which can cause severe paralysis.[30][31][32] C. scutulatus is widely regarded as producing one of the most toxic snake venoms in the Americas, based on LD50 studies in laboratory mice.[33]

Rattlesnake venom is a mixture of 5-15 enyzmes, various metal ions, biogenic amines, lipids, free amino acids, proteins, and polypeptides. It contains components designed to immobilize and disable the prey, as well as digestive enzymes which break down tissue to prepare for later ingestion.[25][29] The venom is very stable, and retains its toxicity for many years in storage.[25]

Older snakes possess more potent venom, and larger snakes are frequently capable of storing larger volumes of it.


Antivenom

Crotaline antivenom (or "antivenin") is commonly used to treat the effects of local and systemic pit viper envenomations.[72] The first step in the production of crotaline antivenom is collecting ("milking") the venom of a live rattlesnake - usually from the Western Diamondback (Crotalus atrox), Eastern Diamondback (Crotalus adamanteus), South American rattlesnake (Crotalus durissis terrificus), or fer-de-lance (Bothrops atrox). The extracted venom is then diluted and injected into horses, goats, or sheep, whose immune systems produce antibodies that protect from the toxic effects of the venom. These antibodies accumulate in the blood, which is then extracted and centrifuged to separate the red blood cells. The resulting serum is purified into a lyophilized powder, which is packaged for distribution and later use by human patients.[73][74]

Because antivenom is derived from horse animal, people generally display an allergic response during infusion, known as serum sickness.




Safety and first aid:-

 Rattlesnakes are the leading cause of snakebite injuries in North America, and are a significant cause in Central and South America.

Avoiding bites:-

 

Rattlesnakes tend to avoid wide open spaces where they cannot hide from predators, and will generally avoid humans if they are aware of their approach.[60] Rattlesnakes rarely bite unless they feel threatened or provoked. A large majority of victims (~ 72%[61]) are males, often young and intoxicated. Approximately half of bites occur in cases where the victim saw the snake, yet made no effort to move away.[25]

Hikers and campers should avoid contact with rattlesnakes by remaining observant and not approaching the animals. Hikers are advised to be particularly careful when negotiating fallen logs or boulders and when near rocky outcroppings and ledges where rattlesnakes may be hiding or sunning themselves. However, snakes will occasionally sun themselves in the middle of a trail, so such areas are not the only places where they are encountered. When encountering a rattlesnake on a trail, hikers are advised to keep their distance and allow the snake room to retreat.[citation needed]

Caution is advised even when snakes are believed to be dead; rattlesnake heads can see, flick the tongue, and inflict poisonous bites for up to an hour after being severed from the body.


Effect of bites on humans
Rattlesnake bite injury:-


Rattlesnake bites are rarely fatal to humans, if treated promptly.[30] Between 7,000 and 8,000 people are estimated to have been bitten by venomous snakes in the United States each year, and about five of those die.[64] The most important factor in determining survival following a severe envenomation is the amount of time elapsed between the bite and treatment. Most deaths occur between 6 and 48 hours after the bite. However, if antivenom treatment is given within 1–2 hours of the bite, the probability of recovery is greater than 99%.[65]

When a bite occurs, the amount of venom injected is under voluntary control by the snake. The amount released is dependent on a variety of factors including the condition of the snake (e.g. having long, healthy fangs and a full venom sack) and its temperament (an angry, hungry snake that has just been stepped on vs. a satiated snake that was merely surprised by walking near it).[66] Approximately 20% of bites result in no envenomation at all. A lack of burning pain and edema 1 cm away from the fang marks after 1 hour, suggests that either no or minimal envenomation occurred. A lack of edema or erythema in the area of the bite after 6–8 hours indicates a lack of envenomation for most rattlesnake bites.[67]

Common symptoms include swelling, severe pain, weakness, anxiety, nausea and vomiting, hemorrhaging, perspiration, and heart failure.[66][68] Local pain following envenomation is often intense, increasing with the ensuing edema.[66] In general, children experience more severe symptoms because they receive a larger amount of venom per kilogram of body mass.


Emergency response:-

Data on the effectiveness of first aid techniques for rattlesnake bites is limited.[69] However, general recommendations for first aid in the field are as follows:

    Remain calm, and retreat from the snake at least 10–15 feet. Arrange to have the victim transported to a medical facility as soon as possible.[69]
    Remove restrictive clothing items (rings, bracelets, watches, buttoned shirts, etc.) from the victim.[69][70]
    Splint or otherwise immobilize any bitten limbs, and keep them below heart level.[30][34][69][71] If (and only if) the victim is more than 1–2 hours away from a medical facility, it is recommended to place a lightly constricting band (that admits one finger beneath it) above the bitten area to prevent the systemic spread of the venom.[69]
    Keep victims calm; put them at rest; keep them warm and give them comfort and reassurance (which will lower their heart rate, slowing the spread of the venom). However, keeping a victim's heart rate down should never interfere with getting him or her to a medical facility.[69]

In no case should tourniquets be used, nor should any incisions or suction be applied to the wound


Food

Journalist Alistair Cooke claims that rattlesnake tastes "just like chicken, only tougher."[82] Others have compared the flavor to a wide range of other meats, including veal, frog, tortoise, quail, fish, rabbit, and even canned tuna.