Rattlesnakes less venomous than their ancestors


This video from North America says about itself:

GoPro falls into pit of rattlesnakes

9 October 2015

Rattlesnake strikes GoPro and knocks it into pit of snakes.

From Science News in the USA:

Rattlesnakes have reduced their repertoire of venoms

Reptiles’ common ancestor possessed greater variety of toxic proteins

By Laurel Hamers

12:00pm, September 15, 2016

Modern rattlesnakes have pared down their weaponry stockpile from their ancestor’s massive arsenal. Today’s rattlers have irreversibly lost entire toxin-producing genes over the course of evolution, narrowing the range of toxins in their venom, scientists report September 15 in Current Biology.

“After going through all the work of evolving powerful toxins, over time, some snakes have dispensed with them,” says study coauthor Sean B. Carroll, an investigator with the Howard Hughes Medical Institute who is at the University of Wisconsin–Madison. These modern rattlesnakes produce smaller sets of toxins that might be more specialized to their prey.

Carroll, an evolutionary biologist, and his colleagues focused on a family of enzymes called phospholipase A2, or PLA2. Genes in the PLA2 family are one of the main sources of toxic proteins in the deadly cocktail of rattlesnake venom. This set of genes can be shuffled around, added to and deleted from to yield different collections of toxins.

Data from the genome — the complete catalog of an organism’s genetic material — can reveal how those genetic gymnastics have played out over time. Carroll’s team looked at the relevant genome regions in three modern rattlesnake species (western diamondback, eastern diamondback and Mojave) and also measured molecules that help turn genetic instructions into proteins. That showed not just how the genes were arranged, but which genes the snakes were actually using. Then, the scientists blended that data with genetic information about other closely related rattlesnakes to construct a potential evolutionary story for the loss of PLA2 genes in one group of snakes.

The most recent common ancestor of this group probably had a large suite of PLA2 genes 22 million years ago, the scientists found. That collection of genes, which probably came about through many gene duplications, coded for toxins affecting the brain, blood and muscles of the snake’s prey. But 4 million to 7 million years ago, some rattlesnake species independently dropped different combinations of those genes to get smaller and more specialized sets of venom toxins. For instance, three closely related rattlesnake species in the group lost the genes that made their venom neurotoxic.

“The surprise is [the genes’] wholesale loss at two levels: complete disappearance from the venom and complete disappearance from the genome,” Carroll says. In other words, some of the genes are still lurking in the genome but aren’t turned on. The proteins those genes produce don’t show up in the venom in modern snakes. But other genes have left the genome entirely — a more dramatic strategy than simple changes in gene regulation.

Environmental shifts might have encouraged this offloading of evolutionary baggage, Carroll says. If a certain snake species’ main food source stopped responding to a neurotoxin, the snake would waste energy producing a protein that didn’t do anything helpful.

Plus, a rattlesnake doesn’t just invest in producing venom. It also needs to produce antibodies and other proteins to protect itself from its own poison, says Todd Castoe, an evolutionary biologist at the University of Texas at Arlington who wasn’t involved in the study. As a snake’s weapon becomes more complex, its shield does too — and that protection can use up resources.

Researchers also found that venom genes might not be consistent even within a single species of rattlesnake, perhaps because snakes in different areas specialize in different prey. One western diamondback rattlesnake that Carroll’s team sampled had unexpected extra genes that the other western diamondbacks didn’t have. His lab is currently looking into these within-species differences in venom composition to see how dynamic the PLA2 genome region still is today.

As for the ancestral rattlesnake, it’s impossible to say exactly how powerful the now-extinct reptile’s venom was, Carroll says. But the wider variety of enzymes this rattlesnake could hypothetically produce would have given it more flexibility to adapt its poison to environmental curveballs — an ability that Castoe describes as “the pinnacle of nastiness.”

Editor’s note: Sean B. Carroll is on the board of trustees of Society for Science & the Public, which publishes Science News.

Big snakes in love, video


This video says about itself:

Have you ever seen??? The biggest and the most dangerous snakes making love in nature

Anaconda mating and king cobra mating.

Scientists have discovered why snakes are so long – and it could help humans with spinal injuries. A quirk of evolution means a particular gene stays ‘switched on’ for longer than usual during snakes’ embryonic development: here.

Smooth snakes, adult and young, videos


This 17 July 2016 video from the Veluwe region in the Netherlands shows an adult smooth snake.

This 12 July 2016 video from the Veluwe region in the Netherlands shows a young smooth snake crossing a path.

Avoiding snakebite harm


This video from the USA says about itself:

14 August 2015

The bull snake hissing, rattling its tail, striking, and all its charms in this video of treasures found and released all over the Great Plains.

From eNature Blog in the USA:

Do You Know How To Treat A Snakebite?

Posted on Friday, July 15, 2016 by eNature

It’s the height of summer and folks throughout the country are visiting parks, hiking through the woods, or otherwise enjoying the outdoors. At the same time, lots of other, non-human, creatures are on the move.

Chances are high you might encounter a snake or two if you’re out. But don’t panic— they’re actually pretty harmless creatures.

Even in areas where there are many venomous snake species, few people ever encounter them, and fewer yet run any real risk of being bitten. Most snakes, even the ones with the worst reputations, will choose to flee when they sense your presence. Snakes usually bite as a last resort.

Remember, fangs and venom evolved primarily for prey capture, not as a defense mechanism. Most snakebites in this country come as a result of people trying to handle or otherwise harass or move the snake; avoid this type of behavior and you will probably never get bitten.

How To Avoid Snakebites

Here are some steps you can take to avoid snakebites:

-Before venturing out into the wilderness, familiarize yourself with the snakes of your area, both venomous and non-venomous species.
-Learn which habitats the venomous species in your region are likely to be encountered in, and use caution when in those habitats.
-Always take a buddy into the field with you.
-Wear boots and loose-fitting pants if you are venturing into venomous snake territory.
-Try as much as possible not to take a snake by surprise. Stay on trails, and watch where you place your hands and feet, especially when climbing or stepping over fences, large rocks, and logs, or when collecting firewood.

How To Treat Snakebites

Despite what we often see in moves or television, venomous snakebites are rare—and if they do happen, they’re are rarely fatal to humans. Of the 8,000 snakebite victims in the United States each year, only about 10 to 15 die. However, for any snakebite the best course of action is to get medical care as soon as possible.

And unlike in movies—never try to suck the venom out of wound with your mouth. Nothing good will come of doing that. Instead, follow the steps below:

-Try to keep the snakebite victim still, as movement helps the venom spread through the body.
-Keep the injured body part motionless and just below heart level.
-Keep the victim warm, calm, and at rest, and transport him or her immediately to medical care. Do not allow him to eat or drink anything.
-If medical care is more than half an hour away, wrap a bandage a few inches above the bite, keeping it loose enough to enable blood flow (you should be able to fit a finger beneath it). Do not cut off blood flow with a tight tourniquet. Leave the bandage in place until reaching medical care.
– If you have a snakebite kit, wash the bite, and place the kit’s suction device over the bite. (Do not suck the poison out with your mouth.) Do not remove the suction device until you reach a medical facility.
– Try to identify the snake so the proper antivenin can be administered, but do not waste time or endanger yourself trying to capture or kill it.
-If you are alone and on foot, start walking slowly toward help, exerting the injured area as little as possible. If you run or if the bite has delivered a large amount of venom, you may collapse, but a snakebite seldom results in death.

Smooth snake in Dutch Veluwe


This 7 July 2016 video shows a smooth snake on heathland near Ede town in the Dutch Veluwe region.

Smooth snake videos


This 1 Juli 2016 video shows a smooth snake near Ede in the Netherlands.

This 4 July 2016 video is about two individual smooth snakes, living at the same heathland near Ede.

Three young grass snakes in well, video


Yvonne Mathot from the Netherlands made this video near her home in June 2016. It turned out these three young grass snakes had fallen into the well. Ms Mathot saved and freed them.