Extract from ABC News
Three families of venomous snakes have been revealed by high-speed cameras to bite prey using different techniques.
In short:
High-speed cameras have been used to capture the biting mechanisms of different kinds of snakes, including vipers and the death adder.
Thirty-six species were filmed with high-speed cameras biting into warm gel that mimics animal flesh in the biggest study of its kind.
Vipers were the fastest of the snakes recorded and would reposition their fangs post-bite for a better mouth position.
Venomous snakes can strike their prey, or people, in a fraction of a second.
But slowing down their bites with high-speed cameras reveals how techniques for delivering deadly venom differs among serpents.
A group of Australian researchers has done exactly that for a new study published in the Journal of Experimental Biology.
The study is the largest of its kind comparing how venomous snakes strike their prey in controlled conditions.
Lead author Silke Cleuren travelled to Venomworld in Paris, where snakes from around the globe are bred to extract venom for medical uses, to find scaly research participants.
Silke Cleuren studies the evolution of snake fangs and biting techniques among venomous species. (Supplied: Silke Cleuren)
Dr Cleuren, an evolutionary biologist at Monash University, and her colleagues recorded the bites 36 species of snakes from across the viper, elapid and colubrid families.
These included the rough-scaled death adder (Acanthophis rugosus) from Australia, the western diamondback rattlesnake (Crotalus atrox) and west African carpet viper (Echis ocellatus).
According to Alistair Evans, study co-author and evolutionary morphologist also at Monash University, it didn't take much to entice them to bite.
Each snake was presented with a warmed-up cylinder of medical gel at the end of a pole to simulate some fleshy food.
"We put eyes on the front of it to make it look like it was an animal-type thing," Professor Evans said.
"We let them strike at it and we captured the strike with high-speed video cameras.
"I'm not going to insult the snakes in the audience, but I don't think snakes are particularly picky when they're choosing their prey,"he said.
The three-dimensional movement of each snake was then reconstructed to calculate factors like their speed and acceleration.
Vipers
Vipers strike fast, and then walk their fangs into the ideal biting position.
Vipers are well known to be some of the fastest striking snakes.
The team found that on average prey was reached within just 100 milliseconds — that's about three times faster than the blink of a human eye.
The fastest — the blunt-nosed or Levantine viper (Macrovipera lebetina) — reached the prey in just over 20 milliseconds.
The Levantine viper (Macrovipera lebetinus) was the fastest snake to get to the gel cylinder, biting it within 21.7 milliseconds from its striking position. (iNaturalist: Aurélien Grimaud, Levantine viper, CC BY-NC 4.0)
Almost all these snakes captured the prey within what's known as the "mammalian startle response".
"If something is moving towards you, you have to see it with enough time to register that it's moving, and then react to it," Professor Evans said.
"Your brain tells your muscles to move, so less than 100 milliseconds is much, much faster than the mammalian startle response, particularly for large mammals like us."
Drops of venom left on the gel cylinder after being bitten. (Supplied: Silke Cleuren)
Vipers have hinged fangs, which allow them to have longer teeth that fold into their mouth when not in use.
During the study, if their initial bite wasn't to their liking, the vipers would "walk" up their fangs into a better position to inject venom.
Vipers were by far the most common species in the survey, making up 31 of the 36 species of snakes available at Venomworld to be analysed.
This family contains some of the most deadliest snakes in the world, causing thousands of deaths a year in Asia and Africa.
Timothy Jackson, a snake venom researcher at the University of Melbourne who was not involved in the research, noted that the study was a large and important analysis into this group of snakes.
"We don't see a great deal of this kind of work," he said
"They convincingly make the case as to why their own study significantly improves our knowledge."
Australia does not have any vipers.
Professor Jackson noted it was important to expand this research for other types of snakes — particularly Australian — but this would be difficult to do.
"It's a significant chunk of work. You'd need to be in collaboration with [a venom facility] and there would need to be specific funding, which is always a challenge for a behavioural study," Dr Jackson said.
Elapids
Elapid snakes bite repeatedly to deposit venom into their prey.
Most of Australia's venomous snakes belong to a family known as elapids, which have fangs in the front of their mouths.
The Australian rough-scaled death adder (Acanthophis rugosus) was one of four elapids studied.
The death adder was extremely fast — able to reach its prey in about 30 milliseconds, and moved at up to 2.21 metres per second.
The rough-scaled death adder (Acanthophis rugosus), found in the Northern Territory and Queensland, was the only Australian snake in the study. (iNaturalist: Brandon Sidelieu, Rough-scaled death adder, CC BY-NC 4.0)
Dr Jackson said the finding confirmed death adders were very similar to vipers in the way they strike.
"Death adders strike extraordinarily quickly and are very much in the viper range … these are incredibly fast strikers," he said.
"In fact, in terms of reaching maximum velocity, death adders were the second fastest species in the entire study."
Elapids have much shorter fangs than vipers, so they creep closer to their prey before striking repeatedly to squeeze in venom.
Dr Jackson noted that much of the study was not "all that surprising", mostly backing up what scientists already knew about snakes.
"But having all of that quantitative analysis to confirm those intuitions is really important," he said.
"I think it's a really cool contribution to venomous snake biology in general."
Colubrids
Colubrid snakes tear gashes in their prey.
The mangrove or gold-ringed cat snake (Boiga dendrophila) from southeast Asia was the sole Colubridae species in the study.
This group of snakes have fangs situated towards the back of their mouth, so they have a different biting style to the vipers and elapids.
Maximum gape, the opening of the snake's mouth, was reached sooner than the other species and held for a longer distance.
Once making contact, the gold-ringed cat snake closed its mouth and dragged its maxilla, a moveable upper jawbone, around to create gaping cuts in the shape of crescents.
The study theorises this could better allow for venom transfer into the snake's prey.
Large gashes were left in the gel cylinder from the rear fangs being swept side to side by a Colubrid snake. (Supplied: Silke Cleuren)
The final velocity of the snake used in the study got progressively faster over three bites from 1m per second to 3.2m per second.
While the mangrove snake uses its venom to target small animals it is not considered harmful to humans.
There are a few Colubridae species in Australia, many of which are non-venomous.
Because only one Colubridae species was included in the paper, Professor Evans noted there could be more variation that we're missing in species from that snake family.
"One of the interesting findings of the paper was how different families of snakes use their venom in different ways," he said.
"We were limited by what they had in Paris. But it's at least the start."
The gold-ringed cat snake (Boiga dendrophila) with its rear fangs was the only member of the Colubridae family in the study. (iNaturalist: Brandon Sidelieu, Gold-ringed cat snake, CC BY-NC 4.0)
Dr Jackson suggested the study could be a blueprint for more research around the world.
"There's a real proof of principle here," he said.
"I hope it can be more broadly applied and also potentially modified for for other studies."
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