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Tuesday, January 4, 2011

Snakes - The Oldest Victims of Prejudice

Fossil of an archaeophis proavus massalongo from Monte Bolca, a site
near Verona, Italy that is an important source of fossils from the Eocene.
This era was from about 37.5 million to 54 million years ago.
Museum für Naturkunde, Berlin 

Inducing fear and dread for possibly millenia, not to mention terror and revulsion, our prejudices for this creature go back to time out of mind.  This creature has been both divine and demonic.  We tend to love them or hate them, and always have.

The etymology of the word "snake" is interesting, because it comes from the same root word as "sneak".  Our current word came from the Old English snaca, from Proto-Germanic *snak-an, in turn from Proto-Indo-European *(s)nēg-o- meaning to crawl or creep.  The Sanskrit word "naga" shares this etymology.
 
Leptotyphlops carlae (thread snake) on a quarter (a quarter is .94")
Image courtesy of Blair Hedges, Penn State

Snakes can be found on every continent except Antartica, and on most islands. They can range in size from the tiny thread snake (shown in the image above on a U.S. quarter dollar coin) with a length of four inches, to the reticulated python, which can be thirty feet long.  Most snakes average about three feet in length.  In 2009, in the open-pit El Cerrejon coal mine in Colombia, the fossil of a snake called Titanoboa cerrejonensis, estimated to be 49 feet long and to weigh 2,500 pounds was discovered.  That length is about the same as a T-Rex.  New species of snakes are still being discovered.

Modern snakes are a diverse group, their evolutionary growth occurring alongside that of mammals after the extinction of dinosaurs.  There are currently over 2,900 known species, from sea dwellers to ones who live 16,000 feet high in the Himalayas.  There are two basic theories for their evolution.  The first  advocates that they came from burrowing lizards in the Cretaceous era.  Snakes lost their external ears and developed transparent eyelids to avoid problems such as scratched corneas and dirt in the ears.  The second theory is that snake ancestors came from aquatic reptiles like the mosasaur.  Transparent eyelids then evolved due to marine conditions, and external ears were lost from disuse.  In the late Cretaceous, snakes colonized land and came to exhibit their present appearance. The fossil record tends to support this now, but in the end may refute both hypotheses.

Rod of Asclepius.  Asclepius was the son of Apollo and a healer.
His attributes were the rod and the snake, in this symbol combined.
This is the true symbol associated with medicine, used by the field.
Drawing courtesy of Wikipedia.

It is a common belief that snakes are slimy, like worms.  This is not true.  A snake's skin is covered in scales giving them a smooth and dry texture.  They shed this skin as a whole when they moult, which replaces the old, worn skin while at the same time getting rid of mites and parasites.  Snakes moult from two to four times a year.  This periodic shedding of the old skin has led to the snake being a symbol of healing and medicine.

The caduceus, the staff carried by Hermes (Greek) or Mercury (Roman).
Often mistakenly used by the medical field.  Hermes/Mercury was the messenger
of the gods, guide of the dead, and protector of merchants, shepherds, gamblers,
liars, and thieves.  It became a popular icon in the Renaissance, associated with
alchemy and wisdom.  Image by Rama and Lash on Wikipedia.

The vision of snakes varies according to species.  Some are only able to distinguish light from dark, while some have keen eyesight.  Generally their vision is adequate and allows them to track movement.  They track their prey primarily by smell.  Their tongues flicker and collect airborne particles, passing them to a specialized organ for analysis.  Their tongues are in constant motion giving them a directional sense of smell and also taste.  Their bodies are also very sensitive to vibrations and can detect vibrations from the air and the ground.  Pythons, pit vipers, and some boas have infrared-sensitive receptors on their heads which allow them to read the radiated heat of warm-blooded prey.

Anatomy of a snake. 1 esophagus, 2 trachea, 3 tracheal lungs, 
4 rudimentary left lung, 5 right lung, 6 heart, 7 liver, 8 stomach, 
9 air sac, 10 gallbladder, 11 pancreas, 12 spleen, 13 intestine, 
14 testicles, 15 kidneys.  Artist:  Uwe Gille from Wikipedia.

Most species are nonvenomous.  Those that are venomous use the venom first and foremost for killing and subduing prey rather than self-defense.  Since venoms are not inhaled or ingested they are technically not  poisons.  Venom is a highly modified saliva produced by special glands, composed of a combination of proteins, enzymes, neurotoxins (attacking the nervous system), cytotoxins (attacking the cells), and coagulants.  For most species of venomous snakes when biting, the venom discharges the moment the fangs penetrate the skin.  The venom is used up after several bites.  Some snakes, like the so-called spitting cobras, can eject venom by spitting, shooting venom up to 4-8 feet.  This is a defensive reaction, and this type of snake aims for the eyes.  There is no danger if the skin is contacted, unless there is an open wound, and if rinsed at once with lots of water there are no serious results, however blindness results if left untreated.

Creator and model:  Mikael Häggström
Image courtesy of Wikipedia.

It has been suggested that all snakes are venomous to a degree, but don't have a delivery system or can't deliver enough venom to harm a human, which leads to the hypothesis that snakes evolved from a venomous lizard ancestor.  Some birds, mammals, and snakes such as king snakes (who prey on venomous snakes) have developed an immunity to venoms.  Although the term "poisonous snake" is a misnomer there are two exceptions.  The rhabdophis genus (also called Keelback snakes) found in southeast Asia, retains the poisons from the toads they eat and secretes it to ward off predators.  Similarly there is a small group of garter snakes in Oregon that become poisonous to predators like foxes and crows from preserving the poisons they ingest from the newts they consume.

Human immunity to snake bites is one of the oldest forms of vaccinology, dating back to ancient tales of the Psylli tribe. Several people have injected themselves with venom successfully achieving immunity.  There is a project to develop a DNA-based vaccine using genes that encode the venom through electropermeabilization, which introduces the venom into a cell.  This will be a godsend for people who live in areas where venomous snakes live.    There are native plants that can help treat snakebites, usually used on domesticated animals, but that can work on humans as well.    It is unfortunate, however, that even where the reactions to snakebites appear the same, different snake venoms are not affected by sera or inoculations that work for others.  Bites from nonvenomous snakes need to be treated immediately, just like bites from dogs, cats, or any creature.

So, enough about the negatives concerning this gorgeous creature.  Keep in mind that humans have used their superior intellect to create weapons of mass destruction, which kill all manners of living creatures, as well as killing things one-by-one (and not just in self-defense), which makes them far more evil and scary.

Swiss-born Italian photographer Guido Mocafico is well-known in Europe for his work.  He has worked for international magazines, and done ad campaigns for the like of Gucci, Yves Saint Laurent, Clinique, Shiseido, and Hermès.  His photography books are spectacular, as he regards many creatures as the work of an unparalleled artist.  But his most beautiful work may be his photographs of snakes. (Note to my husband:  NO!  We are not getting a snake!)

In March of 2008, Steidl published a book of Mocafico's photographs entitled Serpens, with an essay by Ivan Ineich.  Ineich is a French reptile specialist at France's Natural History Museum in Paris.  (P.S. to my husband:  live snake = bad idea; book = good idea.)  Below are just some of his photographs, and it was indeed a hard choice to make which to include.  To see more, go to his website.

Snakes are so remarkable and so beautifully conceived that we should be in awe of them.  They are not vicious, but with no limbs are very restricted in protecting themselves, hence their bite.  Please remember that they bite as a last resort - they would rather be left alone and will flee if given the chance.  Please respect these awesome creatures, and grant them the space they need to feel safe.



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2 comments:

  1. Having just recently been the victim of a copperhead bite, one would think that I would have a fear of or at least a negative attitude towards snakes but I don't. I don't have an innate fear of them and think they are really amazing and beautiful creatures. I also think insects are cool.

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  2. I wish everyone had your attitude, Ellen. They are amazing and beautiful, and considering they have no limbs their bite is the only possible defense when they feel fear, which must be often as they are so poorly treated. I'm so glad you are better, but even more glad you didn't let your experience poison you!

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