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Snakes alive! Expert verdict Professor ROB SMITH is Dean of Applied Sciences at Huddersfield University and a man fascinated by snakes . . . down to having his own pet boa constrictor. Here he tells us why he's such an enthusiast.

Byline: ROB SMITH

I saw the headline "Snake bites woman in Huddersfield" in the Examiner last March, followed four days later by a "Snake bites dog" headline, and thought it was an early April Fool.

But it was no joke to the lady who had been bitten by an adder while walking near Scapegoat Hill, nor to the dog bitten in Bunny Wood (both survived).

I was reminded of this on a recent visit to South Africa where I saw several venomous snakes, all much more hazardous than our native adder.

Not all snakes are venomous, so why do some snakes inject poison through fangs and why don't other animals?

Snakes generally have a bad Press, starting from the book of Genesis in the Bible. In fact, snakes are fascinating and beautiful animals that have evolved a range of unusual features.

Many snakes are beneficial because they eat vermin such as rats and mice. Most snakes are harmless to people, and death through snake bite is uncommon.

In Britain dogs kill many more people than do snakes and cars kill very many more.

Snakes are reptiles and related to lizards, crocodiles and turtles.

Snakes evolved from a group of ancient lizards about 100m years ago by a process of limb reduction.

Pythons and boas still show anatomical remains of legs.

We believe snakes evolved long, thin bodies and lost their legs (and their ears) as an adaptation to burrowing underground. Some lizards are also legless, including the slow worm, which is another native species of southern Britain. But slow worms are not snakes; their skin is smooth and shiny, they have eyes that blink (unlike snakes) and they can only swallow small food items.

Snakes can swallow animals larger than their own heads because they have a very flexible lower jaw and other joints in the skull, hence they can gradually work their head around the prey.

Digestive juices called enzymes begin to break down the prey before it is swallowed.

Swallowing takes some time and only works if the prey animal doesn't make too much fuss! Some snakes (pythons and boas) overcome their prey by biting and quickly coiling themselves around it, then squeezing until it is suffocated. They can tackle goats, and even antelopes in some cases, and spend several months digesting a large meal.

I once had a nasty moment when my pet boa constrictor coiled itself round my neck while I was demonstrating how to handle snakes; or how not to, as it turned out.

The snake would automatically tighten its grip if I tried to pull it off, so I tucked in my chin and waited quietly for what seemed like an eternity until it moved along my outstretched arm and off my neck (please do not try this at home!).

My audience did comment that I looked a little worried.

Other snakes are less patient and speed up death by injecting venom.

It is unusual for venomous snakes to attack unless they feel really threatened.

The main purpose of venom is to help the snake catch and eat prey.

Snake venom is thought to have evolved from digestive juices and some snakes just hold prey with their teeth while the venom dribbles down grooves in the fangs at the back of the mouth.

The venom speeds up digestion from inside the prey as well as killing it. Few other animals eat their prey like this, which is why they have not developed venom.

Some snakes have fangs at the front of the mouth and inject venom that can contain nerve toxins and cause paralysis. These most dangerous species are not found anywhere near Britain (the most venomous are in Australia).

Snake venom is 'costly' for snakes to produce. If they use it up in defence they might miss out on catching food. So venomous snakes may only inject a little or, as often as not, inject no poison when they bite in defence. If you are bitten by a snake just think of this statistic and don't panic! Panic only makes matters worse because it speeds up movement of the venom around the bloodstream.

Never use a tourniquet, cut the wound or suck out the poison.

Recommended treatment is to wrap a crepe bandage firmly above and below the wound, seek medical help promptly and lie down quietly.

Many snakes are brightly coloured with beautiful patterns. This is believed to act as a warning to animals with colour vision (birds, apes, monkeys and humans) to keep away.

Our own adder has a multi-function zigzag pattern. This pattern helps to disguise it when it lies coiled in dead bracken on heathland and can then act as a warning signal when it stretches out.

Other snakes are brightly coloured yet harmless, 'pretending' to be dangerous, but that's another story.

Adders are cold-blooded and lie out in the sun to warm up, especially in spring when they come out of hibernation and in late summer while the eggs are incubating inside the females. These are the times to watch out for them.

To me, snakes are great; they are attractive, interesting and do more good than harm. But it's always advisable to keep your distance.

'In Britain, dogs kill many more people than do snakes and cars kill very many more'

CAPTION(S):

ADDER: Its multi-function zigzag pattern helps to disguise it when it lies coiled in dead bracken on heathland and can then act as a warning signal when it stretches out
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Publication:Huddersfield Daily Examiner (Huddersfield, England)
Date:Jul 29, 2008
Words:916
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