Rattlesnakes can stand a bit of cold


This 2017 video from thed USA is called Explore The Western Diamondback Rattlesnake! | Real Wild.

From the University of California – Riverside in the USA:

Hot or cold, venomous vipers still quick to strike

Cold weather makes rattlesnakes more vulnerable — but not much

July 23, 2020

Most reptiles move slower when temperatures drop, but venomous rattlesnakes appear to be an exception. The cold affects them, but not as much as scientists expected.

“Many reptiles and other animals that rely on external sources of heat have muscles that don’t contract as well when temperature drops. We wanted to know if that was the case with rattlesnakes,” explained UC Riverside biologist Tim Higham.

To answer their question, Higham and a team from San Diego State University examined the speed at which rattlers struck out at perceived threats in temperature-controlled containers. The team’s work is detailed in a new paper published this week in the Journal of Experimental Biology.

The team investigated how quickly the snakes struck out to defend themselves when faced with predators, as this speed can make the difference between life and death in nature.

“Although humans often fear snakes, it is important to realize that snakes are vulnerable to predation by animals such as birds, mammals, and other snakes,” Higham said. “Defensive strikes are important for protecting them against predation.”

When placed in the experimental containers, the research team found that rattlers continued to strike quickly at a balloon filled with warm water that played the role of an intruder.

“By far, the hardest part of the study was working with snakes in the 35 C treatment,” said San Diego State University doctoral student Malachi Whitford, first author of the new study. “The snakes were extremely fast, making them very difficult to corral.”

The strike speed was affected when the temperature dropped, but not as much as the team thought it would be.

“We expected their strike to be about half as fast for every 10-degree drop in temperature, but they’re still able to uncoil and strike fairly rapidly, even at our lowest test temperatures,” said SDSU ecologist and research team member Rulon Clark.

At most, the snakes were about 25 percent slower at the lowest temperature. The finding means that pit vipers, the type of rattlesnake studied, are slightly more vulnerable to real or perceived threats in colder temperatures but not by a lot.

This might help explain how rattlesnakes can thrive even in cooler climates like southern Canada. It also suggests that the snakes are using a mechanism other than just muscles in order to strike, as muscle movement becomes more difficult in the cold.

Kangaroos use tendons like elastic bands to bounce and hop without using much energy, the way that humans use a bow and arrow. The findings suggest that snakes may also be storing elastic energy somehow.

“Striking in any way is important to do quickly,” Higham said. “As global temperatures increase, it’s possible that snakes will become even more effective predators.”

Venomous snakes in Croatia, video


This 9 July 2020 video says about itself:

Croatia has a high diversity of snakes by European standards. Some species are venomous, like the Nose-horned viper (Vipera ammodytes) and Eastern Montpellier snake (Malpolon insignitus).

Living Zoology went for a short trip to Croatia and found both. Nose-horned viper is a front-fanged snake and it was the first venomous snake we found together. That’s why it is in our logo. Malpolon is a rear-fanged species and we found it for the first time during this trip.

How snakes drink, video


This 4 July 2020 video says about itself:

Snakes don’t have lips, they can’t lap up water, and they don’t grab mouthfuls of water and tip their heads back to swallow, so how do they drink? Turns out, some snakes have sponge-mouths that literally soak up water!

Hosted by: Stefan Chin.

How ‘flying’ snakes fly, new research


This 29 June 2020 video says about itself:

Watch a flying snake slither through the air | Science News

Scientists captured the undulating motion of paradise tree snakes as they glide through the sky. A computer simulation based on high-speed video shows that the undulation is necessary for stable flight.

By Emily Conover today:

Here’s how flying snakes stay aloft

Scientists captured the undulating motion of paradise tree snakes gliding from tree to tree

The movie Snakes on a Plane had it wrong. That’s not how snakes fly.

Certain species of tree snakes can glide through the air, undulating their bodies as they soar from tree to tree. That wriggling isn’t an attempt to replicate how the reptiles slither across land or swim through water. The contortions are essential for stable gliding, mechanical engineer Isaac Yeaton and colleagues report June 29 in Nature Physics.

“They have evolved this ability to glide, and it’s pretty spectacular,” says Yeaton, of Johns Hopkins University Applied Physics Laboratory in Laurel, Md. Paradise tree snakes (Chrysopelea paradisi) fling themselves from branches, leaping distances of 10 meters or more (SN: 8/7/02). To record the snakes’ twists and turns, Yeaton, then at Virginia Tech in Blacksburg, and colleagues affixed reflective tape on the snakes’ backs and used high-speed cameras to capture the motion.

Physicists had previously discovered that the tree snakes flatten their bodies as they leap, generating lift (SN: 1/29/14). The new experiment reveals that the snakes also exert a complex combination of movements as they soar. Gliding snakes undulate their bodies both side to side and up and down, the researchers found, and move their tails above and below the level of their heads.

Once the researchers had mapped out the snakes’ acrobatics, they created a computer simulation of gliding snakes. In the simulation, snakes that undulated flew similarly to the real-life snakes. But those that didn’t wriggle failed spectacularly, rotating to the side or falling head over tail, rather than maintaining a graceful, stable glide.

If confined to a single plane instead of wriggling in three dimensions, the snakes would tumble. So snakes on a plane won’t fly.

Timber rattlesnake conservation, new research


This March 2020 video from the USA says about itself:

Considered the most dangerous rattlesnake in the world because of its potent venom and proximity to humans, learn all about the unique adaptations and ecological value of the timber (or canebrake) rattlesnake in today’s episode of The Wild Report!

From Penn State Unversity in the USA:

Habitat for Rattlesnakes: Sunnier but Riskier

Conservation efforts to open up rattlesnake habitat bring in much-needed sunlight but could attract more threatening predators

June 24, 2020

Conservation efforts that open up the canopy of overgrown habitat for threatened timber rattlesnakes — whose venom is used in anticoagulants and other medical treatments — are beneficial to snakes but could come at a cost, according to a new study by researchers at Penn State and the University of Scranton. The researchers confirmed that breeding areas with more open canopies do provide more opportunities for these snakes to reach required body temperatures, but also have riskier predators like hawks and bobcats. The study, which appears in the June issue of the Journal of Herpetology, has important implications for how forest managers might open up snake habitat in the future.

Timber rattlesnakes are a species of conservation concern in Pennsylvania and are considered threatened or endangered in many of the northern states within their range. Like other ectothermic animals, snakes do not produce their own body heat and must move to warmer or cooler areas to regulate their temperature. Timber rattlesnakes typically use sunny, rocky forest clearings to breed, however many of these “gestation sites” are becoming overgrown with vegetation, blocking much-needed sunlight.

“Pregnant timber rattlesnakes typically maintain a temperature 6 to 8 degrees Celsius higher than normal so that their embryos can develop,” said Christopher Howey, assistant professor of biology at the University of Scranton and former postdoctoral researcher at Penn State. “If a gestation site doesn’t provide enough opportunities for snakes to reach that temperature, a snake might abort its litter, or babies might be born too small or later in the season, which reduces their chances of obtaining an essential first meal before hibernation. We wanted to understand if existing conservation efforts to open up the canopy in gestation sites actually do provide more thermal opportunities for snakes, as intended, and if these efforts impact predation risk.”

The research team first quantified thermal opportunities for rattlesnakes in known gestation sites that had open or closed canopies. They logged temperatures within thermal models — essentially a copper tube painted to have similar reflectivity and heat absorbance to a snake — placed in areas where the researchers had seen snakes basking.

“As expected, we found that gestation sites with more open canopies did indeed provide more opportunities for snakes to reach optimal temperatures,” said Tracy Langkilde, professor and head of biology at Penn State. “This confirms that conservation efforts to open up the canopy do what they are intended to do. But we also found that this might come at a cost, in the form of more threatening predators.”

The research team also placed foam models painted like rattlesnakes at gestation sites and monitored for predators using trail game cameras — remote cameras that are triggered by movement. While there was a similar overall number of predators at sites with open canopies and closed canopies, the more threatening species — red-tailed hawks, fishers, and bobcats — only appeared at open sites.

“Our results suggest that there are tradeoffs to any management strategy and that by opening up a gestation site, we may inadvertently put more predation risk on a species,” said Julian Avery, assistant research professor of wildlife ecology and conservation at Penn State. “Our models were slightly less visible to potential predators than actual snakes, so our estimates of predation risk are probably conservative, and the tradeoff may be more pronounced than what we observed.”

Less threatening predators — raccoons and black bears — appeared at sites with both open and closed canopies.

“As far as we know, this is the first time that a black bear has been observed preying on a rattlesnake, or at least a model,” said Howey. “Until now, we always thought that black bears avoided rattlesnakes, but we observed one bear attack two models and bite into a third.”

The team suggests that forest managers should balance canopy cover and predation risk during future conservation efforts, for example by selectively removing trees that block direct sunlight but that do not considerably open up the canopy.

Improving conservation efforts at rattlesnake gestation sites is particularly important because, as far as the researchers know, snakes return to the same sites year after year to breed. If a gestation site decreases in quality, they might leave the site to find a new area, but it is unclear how successful these efforts are and the act of moving to new sites could increase contact with humans.

The researchers are currently radio-tracking actual snakes and directly manipulating the canopy cover to better understand how snakes behave in response to predators at sites with open vs. closed canopies.

“Timber rattlesnakes are an important part of the ecosystem, and where you have more rattlesnakes, you tend to have lower occurrences of Lyme disease because the snakes are eating things like chipmunks and mice which are the main vectors for the disease,” said Howey. “Rattlesnake venom is also used in anticoagulants, in blood pressure medicine, and to treat breast cancer. Our research will help us refine how we conserve these important animals.”

Aesculapian snakes fighting, video


This 17 June 2020 video says about itself:

Snake male combat – males of some snake species fight for dominance during mating season. Non-venomous Aesculapian snakes (Zamenis longissimus) are big long snakes, which are critically endangered in the Czech Republic. This video shows 2 males fighting for the right to mate with a female for over one hour. Both snakes try to push the body of the rival down to the ground. This footage was filmed in the wild nature in the Dyje river valley.

King cobra against spectacled cobra, pit viper


This 10 June 2020 video says about itself:

Deadly venomous king cobra (Ophiphagus hannah) is the longest venomous snake in the world. It feeds on other snakes and monitor lizards.

In this video, there is a big 4-meters long king cobra on the hunt. It eats a Malabar pit viper and then fights with a 2-meters long spectacled cobra. Everything finishes after darkness. This video was filmed in the Western Ghats in India. Watch the amazing king cobra crawl through the forest!

How sea snakes can see under water


This 2014 video is called The adaptations of sea snakes – The Wonder of Animals: Episode 11 Preview – BBC Four.

From the University of Plymouth in England:

Sea snakes have been adapting to see underwater for 15 million years

May 28, 2020

Summary: A study has for the first time provided evidence of where, when and how frequently species have adapted their ability to see in color.

Sea snakes first entered the marine environment 15 million years ago and have been evolving ever since to survive in its changing light conditions, according to a new study.

Research led by the University of Plymouth (UK) has for the first time provided evidence of where, when and how frequently species have adapted their ability to see in colour.

It suggests sea snakes’ vision has been modifying genetically over millions of generations, enabling them to adapt to new environments and meaning they can continue to see prey — and predators — deep below the sea surface.

In an unexpected twist, the study published in Current Biology also suggests that diving sea snakes actually share their adaptive properties not with other snakes or marine mammals, but with some fruit-eating primates.

The research was led by Dr Bruno Simões, Lecturer in Animal Biology at the University of Plymouth, and involved scientists from the UK, Australia, Denmark, Bangladesh and Canada.

Dr Simões, formerly a Marie Sk?odowska-Curie Global Fellow at the University of Bristol (UK) and University of Adelaide (Australia), said: “In the natural world, species obviously have to adapt as the environment around them changes. But to see such a rapid change in the sea snakes‘ vision over less than 15 million years is truly astonishing. The pace of diversification among sea snakes, compared to their terrestrial and amphibious relatives, is perhaps a demonstration of the immensely challenging environment they live in and the need for them to continue to adapt in order to survive.

“Our study also shows that snake and mammal vision has evolved very differently in the transition from land to sea. Sea snakes have retained or expanded their colour vision compared to their terrestrial relatives, whereas pinnipeds and cetaceans underwent a further reduction in the dimensions of their colour vision. This contrast is further evidence of the remarkable evolutionary diversity of snake eyesight.”

In the study, scientists say that despite being descended from highly visual lizards, snakes have limited (often two-tone) colour vision, attributed to the dim-light lifestyle of their early snake ancestors.

However, the living species of front-fanged and venomous elapids are ecologically very diverse, with around 300 terrestrial species (such as cobras, coral snakes and taipans) and 63 fully marine sea snakes.

To try and establish how this diversity occurred, scientists analysed various species of terrestrial and sea snakes from sources including fieldwork in Asia and Australia and historical museum collections.

They investigated the evolution of spectral sensitivity in elapids by analysing their opsin genes (which produce visual pigments that are responsible for sensitivity to ultra-violet and visible light), retinal photoreceptors and eye lenses.

Their results showed that sea snakes had undergone rapid adaptive diversification of their visual pigments when compared with their terrestrial and amphibious relatives.

In one specific example, a particular lineage of sea snake had expanded its UV-Blue sensitivity. Sea snakes forage on the seafloor in depths exceeding 80metres, yet must swim to the surface to breathe at least once every few hours. This expanded UV-Blue sensitivity helps the snakes to see in the variable light conditions of the ocean water column.

Also, most vertebrates have pairs of chromosomes resulting in two copies of the same genes. In some fruit-eating primates, the two copies might be slightly different (alleles) resulting in visual pigments with different spectral properties, expanding their colour vision. This study suggests that some sea snakes used the same mechanism to expand their underwater vision with both UV sensitive and blue-sensitive alleles.

Dr Kate Sanders, Associate Professor of the University of Adelaide and senior author, said: “Different alleles of the same gene can be used by organisms to adapt new environmental conditions. The ABO blood types in primates are a result of different alleles of the same gene. However, despite being very important for the adaptation of species this mechanism is still poorly reported. For vision, it has been only reported on the long-wavelength opsin of some primates but our study suggests an intriguing parallel with diving sea snakes.”

Vipers use colours to escape from predators


This August 2013 video from Britain says about itself:

The enigmatic European Adder (Vipera berus) is one of the hardiest and widespread snakes on earth, and is Britain’s only venomous snake. Unfortunately, it is suffering declines due to a variety of ecological factors. Here we have a fantastic encounter with a creature that’s becoming increasingly difficult to see.

From the University of Jyväskylä – Jyväskylän yliopisto in Finland:

The European viper uses cloak-and-dazzle to escape predators

May 21, 2020

Research of the University of Jyväskylä demonstrate that the characteristic zig-zag pattern on a viper’s back performs seemingly opposing functions during a predation event. At first, the zig-zag pattern helps the snake remain undetected. But upon exposure, it provides a conspicuous warning of the snake’s dangerous defense. Most importantly the zig-zag can also produce an illusionary effect that may hide the snake’s movement as it flees. The research, published in Animal Behaviour 164 (2020), reveals how a single color pattern can have multiple effects during a predation event, thereby expanding the discussion on protective coloration and anti-predator adaptations.

Protective coloration is one of the simplest but most effective tools that prey species use to evade predators. Typically, different color patterns are useful at different stages of a predation event. Some color patterns are cryptic, obscuring the prey from being detected — think chameleons. Other patterns are aposematic, which blatantly advertise a warning to predators — think wasps. Finally, some patterns can produce optical illusions to startle or confuse predators and give the prey an escape opportunity — think zebras.

But a recent series of experiments, by a team headed by Janne Valkonen and Johanna Mappes at the University of Jyväskylä (Finland), suggests that European vipers (Vipera sp.) can achieve all three tricks with a single color pattern — their characteristic zig-zag.

At first, the zig-zag pattern helps the viper to hide. The researchers hid plasticine models of snakes with different color patterns along paths and noted how often they were detected by people walking the trail. Models with the zig-zag pattern were detected less often than plainly colored models. This is the first confirmation that the viper’s zig-zag pattern provides a cryptic function. But even if the viper is detected, the zig-zag can still work its magic — instead of hiding the snake, the pattern now functions to make it more obvious. Previous research has already established that the pattern warns predators about the snake’s dangerous bite.

The rapid flickering from the zigs and zags of a fleeing snake can produce a ‘flicker-fusion effect’ to mammalian predators.

The most significant contribution from Dr. Janne Valkonen’s study deals with a particular class of illusion generated by the zig-zag pattern. Just as how a rapid series of still pictures can produce a smooth animation, the rapid flickering from the zigs and zags of a fleeing snake can produce a solid shape.

The team measured the speed of fleeing snakes and calculated the flicker rate of the zig-zag. To an observer, a rapidly changing stimulus (such as a moving zig-zag, or spinning helicopter blade) is perceived as continuous if the flicker rate exceeds a threshold in the visual system.

The researchers found that the zig-zag moved quickly enough to produce such a ‘flicker-fusion effect’ to mammalian predators, although the quicker eyes of a raptor won’t be fooled. The effect of this illusion may change the appearance of the moving snake, making it harder to catch. So, like a skilled illusionist, the viper hides by revealing.

The viper’s zig-zag seems to be a simple pattern, but it is a masterful illusion that can hide, reveal, and paradoxically achieve both at the same time. Similarly, this research resolves theoretical tensions between apparently opposing functions of color patterns. That is, crypsis and aposematism seem mutually exclusive: one is meant to blend an animal into its surroundings, the other to make it stand out.

However, through the magic of movement and optics, both functions can be gained through the same pattern at different stages in the predation sequence. Furthermore, the one-to-many aspect of the zig-zag to its antipredator functions implies a far broader scope for the evolution of color patterns and antipredator adaptations than simple one pattern-to-one function relations.

Indian venomous snakes, how many bitten?


This 23 May 2020 video says about itself:

How many people are bitten by venomous snakes in India?

Venomous snakes, like spectacled cobras, Russell’s vipers or common kraits are very common and are responsible for many human bites in India. But how many of them happen each year? How many incidents happen with tigers or elephants? Who is causing bigger human-animal conflict?