Nerodia

Nerodia is a genus of nonvenomous colubrid snakes commonly referred to as water snakes.

Description
Nerodia species vary greatly, but all are relatively heavy-bodied snakes, sometimes growing to 1.2 m (4 feet) or larger. They have flattened heads, with small eyes that have round pupils, and keeled scales. Species like N. fasciata display distinct banding, where other species, like N. erythrogaster have blotching, and N. rhombifer have diamond-shaped patterning. Most species are brown or olive green, or some combination thereof with markings being brown, or black. Yellow or cream-colored accenting is common.

blotched water snake, Nerodia erythrogaster transversa

Behavior
Water snakes, as their name implies are largely aquatic. They spend the vast majority of their time in, or very near permanent sources of water. Often they can be found basking on tree branches which overhang slow moving streams or ponds. Their primary diet is fish and amphibians, and they are quite adept at catching both in their aquatic environment. They will also consume rodents.

While their initial instinct is to flee when disturbed, they do typically have a nasty disposition. They do not often hesitate to strike or bite if handled, and will often expel a foul-smelling musk from their cloacae.

Reproduction

Nerodia species are ovoviviparous, breeding in the spring and giving birth in the late summer or early fall. They are capable of having 90 or more young, but broods generally are much smaller. Neonates are around 20-26 cm (8-10 in.) in length.

diamondback water snake, Nerodia rhombifer giving birth

diamondback water snake

In captivity

Due to how widespread and extremely common they are in the wild, water snakes are often found in the exotic pet trade, throughout the United States, though they are rarely captive bred. Their relative physical unattractiveness compared to other available pet snake species, and their poor disposition makes them less than attractive pets. They are easy to care for though, and do quite well in captivity.

Conservation concerns
Some species, such as N. harteri and N. paucimaculata are only found in very isolated localities and are protected by state laws, but the majority of Nerodia species hold no specific conservation status. Due to their habitat choice, poor disposition, and vague similarity to the venomous cottonmouth (Agkistrodon piscivorus), they are frequently mistaken for them. This results in many more water snakes being killed every year than cottonmouths. Often, water snakes found in areas where the cottonmouth does not range are still killed by humans out of ignorance and fear.
Nerodia species are widely spread around the southern and eastern half of the United States, north into Canada and south into Mexico, as well as to the island of Cuba. Many ranges overlap, and intergrading of subspecies is not unknown, but is rare.

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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.

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venomous snakes of the world

Belcher's Sea Snake ( Hydrophis Belcheri )
Snake's Description : Hydrophis Belcheri's thin body is usually chrome yellowish in colour and is surrounded by dark greenish bands. Head is short and has same color as that of bands. Its mouth is very small but suitable for aquatic life. Its body when viewed outside water appears having fainted yellow colour.

Snake's Characteristics : Hydrophis Belcheri is a sea snake. Its scales are different from other snakes and they overlap each other. Dorsal pattern does not extend on to venter, it has scales with a central tubercle. It is highly compressed at the rear end of the body and has a short head. Abdominal board is very narrow or non-existent. Like other sea snakes it also has a paddle-like tail which make him an expert swimmer. It rarely goes on land, eats fish and shellfish. It breaths air, has valves over its nostrils that close underwater. It can hold its breath for as long as 7 to 8 hours while hunting and even sleeping but then has to come over water surface for a quick breath of air. It is a docile specie and not aggressive at all. It is usually active at night. It may deliver a provoked bite only after repeated severe treatment. It usually bites fishermen handling nets but only 1/4th of those bitten are envenomated since Hydrophis Belcheri rarely injects any venom. Few milligrams (mg) of Belcheri's myotoxic venom is enough to kill an estimate of more than 1000 people. If Belcheri injects, sure death within few minutes. Painful death may even take less time depending on victim's body size and time taken by infected blood to reach its vital organs. It is the most toxic venomous specie of snake known to date and holds a record in Guinness Book.

Snake's Length : Hydrophis Belcheri range from 0.5 to 1 metre in length.

Snake's Distribution : Its main habitat is the Ashmore Reef in the Timor Sea off north-western coast of Australia. It is also found in seas of Indonesia and the South Pacific, having been recorded in the Philippines near Visayan and Panay islands, Gulf of Thailand, Sulawesi, New Guinea, Fiji, Kiribati, and the Solomon Islands.

Hydrophis Belcheri (Belcher's Sea Snake) is not ranked nor included in my top tens due to its non-terrestrial nature and limited human encounters. Even if it bites it rarely injects any venom, though being most venomous it is not most dangerous at all.

Inland Taipan ( Oxyuranus Microlepidotus )
    Western or Inland Taipan (Oxyuranus Microlepidotus) (Fierce Snake),
    Central Ranges Taipan (Oxyuranus Temporalis),
    North-West Australian Taipan (Oxyuranus Scutellatus Barringeri),
    Papuan Taipan (Oxyuranus Scutellatus Canni), and
    Costal Taipan (Oxyuranus Scutellatus Scutellatus).

Snake's Description : Generally Taipans are uniformly olive or dark brown, the head is somewhat darker brown.

Snake's Toxic Rank 1 : Inland Taipan is the world's most venomous land snake. Its bite is synonymous with death. Maximum survival time recorded after Taipan's bite is not more than few hours. Without prompt medical assistance its victim has rarest chance of recovery. Taipans are divided into following five sub-species viz; Western or Inland Taipan (Oxyuranus microlepidotus) or (Fierce Snake), Papuan Taipan (Oxyuranus s. canni), Common or Coastal Taipan (Oxyuranus scutellatus), Central Ranges Taipan (Oxyuranus temporalis) and North-West Australian Taipan (Oxyuranus scutellatus barringeri). Here Inland Taipan (Fierce snake) is the most toxic specie of all. Maximum yield recorded from a single bite of Inland Taipan is 110 mg. Just few mg of Inland Taipan's venom is enough to kill over 100 people or 250,000 mice. Australia's Western or Inland Taipan or Fierce Snake is the world's most toxic terrestrial snake. (Ranked No.1)

Snake's Characteristics : It is considered as the most venomous land snake on earth. Many people believe Taipans are very aggressive but the fact is that they are docile creatures. Yes they have an aggressive disposition only when mishandled or disturbed without warning. When aroused, Taipan can display a fearsome appearance by flattening its head, raising it off the ground, waving it back and forth, and suddenly striking with such speed that the victim may receive several bites before it retreats. Its venom is a powerful neurotoxin, causing respiratory paralysis.

Snake's Habitat : At home in a variety of habitats, Inland Taipan are found from the savanna grasslands to the inland dry plains of Australia. Where as 'Oxyuranus scutellatus' are often seen in forests and open woodlands. Very less or no information; regarding newly discovered Central Ranges Taipan (Oxyuranus temporalis).

Snake's Length : Average Taipan's length is 1.8 meters and maximum of 3.7 meters.

Snake's Distribution : Taipans (Oxyuranus scutellatus) are found in Northern Australia and Southern New Guinea. Whereas Inland Taipan (world's most toxic land snake) are found in Central Australia. Papuan Taipan (Oxyuranus s. canni) are found in New Guinea.


Comman Indian Krait ( Bungarus Caeruleus )

Snake's Description : Comman Indian Krait is black or bluish-black in colour with white narrow crossbands and a narrow head.

Snake's Toxic Rank 2 : Comman Indian Krait is world's No.2 venomous snake. It is highly venomous snake after Inland Taipan (Oxyuranus microlepidotus).

Snake's Characteristics : Kraits are found only in Asia. This poisonous snake is of special concern to man. It is 15 times more deadly than any common cobra. It is active at night and relatively passive during the day. The native people often step on kraits while walking through their habitats. The krait has a tendency to seek shelter in sleeping bags, boots and tents. Its venom is a powerful neurotoxin that causes respiratory failure. Comman Indian Krait is most venomous snake of indian peninsula. In other words, it is the most venomous snake of India, Sri-Lanka and Pakistan.

Snake's Habitat : Comman Indian Krait's habitat include open fields, human settlements and dense jungle.

Snake's Length : Comman Indian Krait's average length is about 90 centimeters and maximum of 1.5 meters.

Snake's Distribution : Comman Indian Krait are found in India, Sri Lanka and Pakistan.




Philippine Cobra ( Naja Philippinensis )

Snake's Description : Philippine Cobra is a relatively small stocky brown snake.

Snake's Toxic Rank 3: Philippine Cobra is the world's No.3 venomous snake. Extremely poisonous snake after Common Indian Krait. Please don't judge this snake on its small size, it is most deadliest snake from Philippine.

Snake's Characteristics : Philippine Cobras are recognized by the hoods that they flare when angry or disturbed. The hoods are created by the extension of the ribs behind the cobras' heads. Philippine Cobras are famous for their use by oriental snake charmers because they respond well to visual cues. Philippine Cobra is Philippines most poisonous snake.

Snake's Habitat : Philippine Cobra's habitat also include open fields, human settlements and dense jungle.

Snake's Length : Philippine Cobra's average length is usually up to 100 centimeters.

Snake's Distribution : As it name says Philippine Cobras are found in Philippine Islands.

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