Even the hearts of cold-blooded reptiles respond warmly to the company of “friends”, scientists researching rattlesnakes in the US have discovered. Two rattlesnakes together can, like people, change each other’s heart rate when thrown into a stressful situation.
“The rattlesnakes could buffer each other’s stress response, much like what happens to humans when they endure a stressful event together,” said study first author Chelsea Martin, from Loma Linda University in California. “This dampening of the stress response has not been reported previously in any reptile species.”
The study, released on Thursday, is the latest research “suggesting that snakes can exhibit complex social behaviours”.
Snakes are secretive and much about their behaviour is not yet known, says South African herpetologist Johan Marais, author of the new edition of The Complete Guide to the Snakes of Southern Africa.
For example, nobody has any idea where underground Cape cobras or black mambas lay their eggs said Marais, CEO of African Snakebite.
What is known is that the baby snakes cut their way out of eggs with a sharp bony projection and must fend for themselves.
Marais dispelled the myth that young snakes are more deadly than adults because they lack control over their venom. “This is not true. Juvenile snake venom is similar to adults and they have a much smaller venom yield, so they are not nearly as dangerous as the adults.”
But mostly snakes stay away from humans, and some species have only been spotted a few times over decades, Marais said in a presentation on Wednesday.
Early zoologists classified snakes with worms and eels — also long, slender animals — but this changed after they noticed snakes had more in common with lizards, had teeth and a venom-delivery apparatus.
Juvenile venomous snakes are not nearly as dangerous as the adults.
— African Snakebite CEO Johan Marais
Describing and classifying snakes is vital to their conservation said Marais.
Iconic snakes in South Africa, like the African rock python, confront threats from humans despite being a protected species.
The Berg adder was the first snake identified in South Africa back in 1758 and new species are still being discovered, such as the yellow spotted mountain snake, first identified in the late 1980s.
A parks board official received the first live specimen of the species and put it in a fish tank, preparing to describe it later, but the rare snake escaped before he could. Finally in 1991 the snake was seen again near the summit of Sani Pass and there has been no confirmed sighting of it over the past 30 years, Marais said.
Other snakes are put at risk by the built environment, like the endangered Albany adder, which was first found on a cement factory site, he said. This adder has, however, since been sighted in Addo, but less than 30 of them have ever been seen.
Over time new species evolve: the Berg adder now has at least four, possibly five species in Southern Africa. Since the mid-90s, DNA analysis has been used to identify species.
This has ramifications from people too, for example, the Berg adder found in the Western Cape has a far more potent venom than those elsewhere.
One study shows that people stopped breathing after four to seven hours after being bitten, as well as having vision problems and losing their sense of taste and smell.
South Africa has had a serious shortage of antivenom this year — which has hit vets hardest — but the scarcity is being resolved, said Marais.
Most people taken to hospital are treated for symptoms not given antivenom. Treatment and antivenom for severe complications can cost up to R100,000 a case.
Marais urged South Africans not to kill snakes, but to call one of more than 700 snake removal experts across the country to assist them if they need a snake removed.
As the new rattlesnake study reveals, snakes also get stressed. In their experiment, the scientists took 25 wild-caught southern Pacific rattlesnakes and tested their reactions in three scenarios: “alone, in the presence of a rope that served as inanimate control object, and in the presence of a same-sex companion”.
They put electrodes near the snakes’ hearts and put them in a dark bucket for about 20 minutes. Then they disturbed the snakes and watched their heart rates increase, and return to normal, and measured the time they spent rattling.
“When exposed to stress, the presence of a snake companion reduced the change in heart-rate of snakes significantly,,” the peer-reviewed study, published in the journal Frontiers in Ethology, found.
When it comes to Southern African snakes, the first stop is surely Marais’s revised guide which has new data collected over the past 20 years — and he is still researching snakes.
When it comes to identification, he has a simple tip (besides his book): always look at distribution.
“If you find a 30cm black snake in Pretoria people are going to think it is a black mamba because everything that is black, people think is a black mamba. Black mambas first of all don’t occur in Pretoria ... and when a black mamba hatches from an egg it is already half a metre long. When you see a tiny black snake it cannot be a black mamba,” he said of SA’s most deadly species.
*The free African Snakebite Institute app has information about local species, first aid, the removal of snakes and a wealth of other information on snakes.
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