Monday, November 24, 2008

The list of venomous snakes around the world includes:

American Copperhead
Coral Snake
Eastern Diamondback Rattlesnake
Eyelash Pit Viper
Jumping Viper
Mojave Rattlesnake
Tropical Rattlesnake
Western Diamondback Rattlesnake
Common Adder
Long-Nosed Adder
Pallas’ Viper
Ursini’s Viper
Bush Viper
Common Cobra
Egyptian Cobra
Gaboon Viper
Green Mamba
Green Tree Pit Viper
Habu Pit Viper
Horned Desert Viper
King Cobra
Levant Viper
Malayan Pit Viper
Mcmahon’s Viper
Mole Viper or Burrowing Viper
Palestinian Viper
Puff Adder
Rhinoceros Viper or River Jack
Russel’s Viper
Sand Viper
Saw-Scaled Viper
Wagler’s Pit Viper or Temple Viper
Australian Copperhead
Death Adder
Tiger Snake

Monday, November 17, 2008

Snake-Fang Evolution Mystery Solved -- "Major Surprise"

Biologist Freek Vonk goes eye to eye with the longest venomous snake species in the world—a female king cobra—in the Indonesian rainforest.

James Owen
for National Geographic News

July 30, 2008

The diverse and deadly array of venomous snakes living today all arose from a single fanged ancestor, a new study suggests.

Vipers, cobras, and other snakes that have fangs at the fronts of their jaws surprisingly begin life like snakes that have poisonous fangs at the back of their jaws, said a team led by Freek Vonk of Leiden University in the Netherlands.

The discovery suggests venomous fangs—the lethal evolutionary invention that led to snakes becoming so successful—arose only once about 60 million years ago.

The origins of venom-injecting snakes have long been the source of scientific controversy, because the contrasting fang positions of diverse snake groups pointed to independent evolution.

But a study of the embryos of eight front- and rear-fanged species has found that fangs always first appear at the back of the upper jaw before migrating forward in vipers and cobras.

This previously unidentified transformation in the unborn young occurs due to "rapid growth of some parts of the upper jaw relative to the others," Vonk explained.

Single Origin

"It's a major, major surprise," the zoologist said of the findings, which will appear tomorrow in the journal Nature.

"There was no significant evidence before for such a single origin of fangs."

Furthermore, the team may have identified the prehistoric mechanism that allowed snake fangs to develop from teeth.

The findings suggest the rear of part of the reptiles' tooth-forming layer in the upper jaw long ago became uncoupled from the rest of the jaw, enabling the back teeth to evolve independently with the venom gland.

"This uncoupling idea is totally new," Vonk said.

"Snakes evolved the fangs once, probably by an uncoupling between some rear and front teeth, and then after that they just played with the [fang] position within the embryo."

This theory makes absolute sense from an evolutionary standpoint, he added, since snake fangs are unique among vertebrates.

"It would be very difficult to assume that snakes had miraculously invented fangs at different occasions," Vonk argued.

The jaw uncoupling may have occurred as far back as 60 million years ago, "at the base of the advanced snake tree."

Venom Systems

After that, Vonk added, "the different lineages could evolve their highly sophisticated venom systems."

Of the 3,000-odd snake species living today, advanced snakes (which are nearly all venomous) number around 2,700, he noted.

Johannes Müller, a reptile fossil expert and curator at the Museum für Naturkunde in Berlin, Germany, said, "I think this is a very important study which, from a novel perspective, sheds new light on our understanding of advanced snake evolution.

"The study shows that advanced snakes seem to share a common, and highly modified, developmental mechanism in the upper jaw," said Müller, who wasn't involved in the new study.

"It supports the view that the developmental tool kit for becoming venomous evolved only once, and the different advanced snake lineages then took advantage of it in various ways," he added.

Saturday, November 8, 2008

Modern Myths About Snakes

Below is a list of common myths regarding snakes and snake behavior and some possible explanations for these tales.

Charming Snakes
A popular myth about snakes is that they are somehow able to hypnotize or "charm" their prey so that the prey is unable to escape. There is no evidence to support the claim that snakes charm their prey. This myth may have resulted from the observation of small animals and birds becoming "frozen with fear" when confronted by snakes, however they are not being charmed. Often an adult female bird will flutter about in front of a snake in order to distract the snake from the fledglings in her nest. Another possible explanation may be that many animals are unable to perceive the slow approach of a long thin snake as dangerous. Finally, the fact that a snake is unable to blink may have something to do with the origin of this myth. Rat snake (Elaphe obsoleta)

Hoop Snakes
According to folklore, when frightened a hoop snake will bite its tail and form a rigid circle which allows it to travel downhill like a wagon wheel. Obviously, snakes are not anatomically equipped for rolling. There are no reliable accounts of this event ever taking place. The hoop snake myth may have originated from the observed behavior of mud snakes. Mud snakes in the southern United States will occasionally lie in a loose coil shaped like a loop, but when confronted they slither away from danger like other snakes.

Poisonous Breath

Some people believe that hognose snakes (Heterodon platirhinos; also called spreading adders or puff adders) are able to mix poison with their breath and kill a person at a distance of over twenty feet. In reality the breath of hognose snakes is harmless. Hognose snakes exhibit perhaps the most elaborate bluffing behavior of any snake. They may spread their hoods, hiss, and even strike, although they don't attempt to bite. If they are continually harassed, they will flip over on their back and play dead. Hognose snakes rarely bite people and their bite is usually less bothersome than a bee sting. Eastern Hognose Snake (Heterodon platirhinos)

Rattlesnakes Add One Rattle Every Year

It is often suggested that rattlesnakes add one rattle every year. Contrary to this belief, a rattlesnake adds one rattle every time it sheds its skin. Snakes may shed several times a year, each time adding a new rattle; in addition rattles may break off. For these reasons, counting rattles is not usually an accurate method of determining a rattlesnake's age.

Snakes Travel in Pairs
Another myth regarding snake behavior is that snakes travel in pairs, the survivor seeking revenge if one is killed. This myth is entirely false, snakes hardly ever travel in groups or pairs. Snakes do not have any social bonds and would feel in no way vengeful if one of its conspecifics were to be killed. One possible explanation for this myth may be that in a prime habitat situation, several snakes of the same species may be observed in a small area. Another possible explanation for the origin of this myth could be related to the typical reproductive behavior of snakes. During the mating season a male snake may closely follow a female snake much as a buck deer trails a doe during the rut.

Unfortunately some people are uninformed about the striking capabilities of snakes. Many people believe that snakes can only strike from a coiled position. In reality, snakes can bite or strike from any position. Coiling does however, increase the distance that a snake can strike. A common inquiry relating to cottonmouths (Agkistrodon piscivorous), concerns their ability to bite underwater. Cottonmouths can in fact bite underwater, which makes sense since they live in wetland habitats, and feed on fish and water snakes.

A related myth states that injured snakes die before sundown. This myth is of course false. A mortally wounded snake will usually die quickly, just like any other animal. Time of day has no bearing on the death of any animal. The origin of this myth may be related to the fact that nerve reflexes may cause muscle twitches for several hours after death, resulting in movements of the body and jaws. Because of the lingering nerve reflexes, even a dead venomous snake can be dangerous.

Sucking Milk
In farming communities throughout the world, it is a common superstition that snakes suck the milk from cows and goats. In North America, the milksnake (Lampropeltis triangulum) acquired its common name based on this myth. Although milksnakes may be common around barns, they lack the anatomical structures necessary to suck. A snake drinks by submerging its head, or at least its mouth, in water and it then takes in water by expanding its body wall. Milksnakes are common in barns because barns house an abundant supply of small rodents, their primary prey.

Swallowing Young
Many people believe that mother snakes will swallow their young when confronted with danger. Despite countless hours of observation, this behavior has never been documented. Swallowing young would not serve as a protective strategy in snakes because anything that enters the esophagus soon arrives in the stomach where it is promptly digested. Although thousands of dissections have been performed on female snakes, none have revealed a stomach full of baby snakes belonging to the same species.

Monday, November 3, 2008

‘Decline in snake population responsible for crop losses’

November 3rd, 2008 • Related • Filed Under
Filed Under: A-Zoo News
Tags: Agriculture Sector • Ecological Changes • Ecological Zones • Natural Enemies • Poisonous Species • Population Of Snakes • Reptiles And Amphibians • Snake Population • Species Of Snakes • Zoological Gardens

Monday, November 03, 2008

The sharp decline in the population of snakes due to ecological changes is harming the agriculture sector, as the population of rats and other rodents is on the rise, said former director of Karachi Zoological Gardens Dr A. A. Quraishy.

According to Quraishy, growing deforestation was responsible for the decline in the population of snakes. The minimum requirement of an environment-friendly country was to have 25 per cent forest cover. This is in stark contrast to arid zones in Pakistan, where only 12.5 per cent forest cover existed.

Due to a very sharp decline in forestation and destruction of natural flora, the forest cover had reduced to 0.2 per cent all over Pakistan, and reflected desertification, claimed Dr Quraishy. Owing to the absence of natural cover, fauna-like mammals, birds, reptiles and amphibians have disappeared from Pakistan, he observed.

In this context, the decrease in snake population is harmful for the agricultural sector. Snakes are necessary for good agriculture produce as they eat natural enemies of crops, including rats and rodents, he said. Field rats are reported to consume about 25 per cent agriculture crop, while the presence of snakes in agricultural fields is necessary to reduce their population and to ensure the safety of crops, he added.

He said that in rural areas the destruction of crops due to increase in population of field rats was alarming. He said that 30 to 50 per cent of the crop yield was being destroyed by rodents.

Both poisonous and non-poisonous species of snakes that were once found in the country are now endangered in quality and quantity in deserts, arid zones, grassy landscapes, marshes, fresh water and other ecological zones of Pakistan, added Dr Quraishy.

He said that the present destruction and deforestation in lower Sindh and Balochistan had driven snakes out of their lairs, rocky abodes, grassy and bushy patches in the hinterland. Desperate and confused, these snakes run into the marshy outback, even entering dry patches, derelict huts and abodes left by the locals in hundreds of villages in lower Sindh and in the coastal belt of Balochistan, he said.

He added that the vicinity of villages suited them best as they provided them with their staple food - the field rats - that dug under the soft land of the cultivated fields, orchards, farms and nurseries.

Desert lizards, some twenty different species of small, medium and large size, also resided in these habitats, where they found shelter, food and breeding sites, said Dr Quraishy. The sandy dunes, banks of rivers and streams also helped them to escape from enemies, to digest their meal or to bring down their escalated body temperature in scalding summer, he added.

He said that the flood and showers wash away the wild grasses while stunted bushes and seasonal creepers help snakes and lizards to survive through changing seasons of the semi-desert. In Balochistan, there was a period when they could find cool strata in holes that they would dig, so as to survive the harsh summers and to hibernate in the winter. The same holds true for Sindh, where snakes lived in the vast expanse of desert.

The sharp decline in the population of the poisonous, non-poisonous snakes and lizards has increased the rate of breeding of at least twenty species that destroys around 30 to 50 percent of crop yield in fields, barns, storehouses and godowns, he said.

Dr Quraishy said that a healthy population of these reptiles in the past has kept rat population low. In the current situation, the heavy loss of food grains has also increased poverty and escalated the Gross National Product (GNP) gap on a national scale, he added.

The incessant capture of snakes and lizards for laboratories and the unchecked export of these species are mainly responsible for the sharp decline of these very environment and agricultural friendly fauna, he claimed.

He claimed that the laboratories have been using them for decades to milk and exploit the venomous snakes to manufacture sera against snakebites. After milking, they are not released in their original habitats, he claimed.

Dr Quraishy said that the death toll by snakebites had diminished just a whiff but the gross imbalance between the prey-predator levels had increased deaths by malnutrition in villages that were eating less food than their minimum nutrition requirement.

The increased rat population robs their crops at every level – in the seedpods, in barns and in homes where they spoil a great deal by their smelly droppings and urine, he said.

Dr Quraishy said that snake charmers were also starving as they did not find enough cobras and colourful non-poisonous snakes with which they used to amuse spectators, who in turn used to pay them for their love of labour, melodious gourd flute and antics.

Saturday, November 1, 2008

Fla. fire-rescue puts antivenom bank to use

By Sallie James
The (Fort Lauderdale) Sun Sentinel

HOMESTEAD, Fla. — Members of Miami-Dade County's Venom Response Team call him a frequent flier because he has been bitten by venomous snakes so many times.

It happened again this past weekend, when longtime snake handler Albert Killian, 52, was cleaning out the cage of a deadly poisonous king cobra.

Killian was bitten by a snake that he once described as having "enough venom to drop an 8,000-pound elephant."

The animal curator at the nonprofit Everglades Outpost Inc. of Homestead was bitten in the left forearm shortly before 3 p.m. Sunday, according to Miami-Dade Capt. Ernie Jillson, who's in charge of the Venom Response Team.

Killian was taken to Homestead Hospital, where he had received more than 20 vials of anti-venin.

"It's an inherent risk that goes along with the job," Jillson said. "When you work with venomous snakes, it's not a matter of if, but when you will get bit. He wasn't doing anything wrong. He was doing what he normally does to take care of the snake."

Killian is "through the worst of it" and will likely be released in a few days, he said.

The bite from a king cobra can cause internal bleeding and respiratory failure, among other things.

"He was fortunate," Jillson said. "Without our anti-venin bank, he would not have survived."

Miami-Dade County Fire Rescue Department operates the only anti-venin bank of its kind in the United States, Jillson said. The agency has 43 antivenins for an array of reptile, insect and spider bites. It is currently the sole available public source in the U.S. for coral snake anti-venin.

In June, Killian spoke to the Sun Sentinel about the risks of handling venomous snakes and his love for the job. During the interview, he handled several snakes, including the king cobra that bit him Sunday, as well as a coral snake.

During the demonstration, Killian grasped the cobra with bare hands, then bent forward and kissed it on its head.

At another point, the snake swiped at Killian's bare leg.

"I've had my heart stop on me once, I've been in respiratory failure three times, and I've been in paralysis three times due to the bites of snakes," he said in June. "The worst thing about a neurotoxic bite is when you go into respiratory failure, and go into paralysis, your brain is completely awake. If someone lifts your eyelids, you can see them."

At the time of the interview, Killian told the Sun Sentinel his last venomous snake bite had occurred about four years earlier, when a Western diamondback rattlesnake struck him with a single fang during a demonstration for a group of students.

Killian, who began handling venomous snakes when he was in his 20s, considers every snake bite a learning experience. He acknowledged that the craft is risky, unpredictable business.

His left ring finger is permanently crooked from the tissue damage caused years ago by rattlesnake bite.

"Do it well when you do it, and don't do it often," Killian told the Sun Sentinel, chuckling.