| 1 | Saw-scaled viper |
Maximum length: usually 50cm, 80cm in certain regions (Rajasthan).
The saw-scaled viper (Echis carinatus) is a resident of dry landscapes in India, which kills dozens of villagers and farmers per year. This species is found in semi-arid deserts with little rainfall, including dry rural areas and barren rocky plains.
Saw-scaled vipers have various desert adaptions, including sidewinding movements to glide effortlessly over soft sands without burning themselves. However, another is the ability to feed on scorpions. Arthropods comprise 65% of their diet, which is far higher than in their African relatives such as the painted saw-scaled viper, which mainly eats vertebrates.
According to a 2009 study, the Indian saw-scaled viper even has a specially tailored venom against scorpions, with a far more powerful LD50 score than against other animals. Meanwhile, the painted saw-scaled viper had no advantage against scorpions, as it preyed on them far less.
Scorpions are formidable opponents, and despite their advantages, saw-scaled vipers are still cautious about biting them. Their strategy is to deliver one sudden bite and immediately let go, standing back safely, and never holding on like a python. They might then deliver a second strike, for a fresh influx of venom, but this can be up to 40 minutes after the original strike.
| 2 | Aquatic coral snake |
Maximum length: 139cm.
The most water-dwelling of the 80-plus coral snakes of the Americas. The aquatic coral snake (Micrurus surinamensis) lives in humid waterways of the Amazon rainforest, gliding through rivers, searching for its mainly fish prey. It reaches a maximum of 139cm, with an average of 80-100cm.
The aquatic coral snake eats far more fish than its cousins, which rely mainly on fellow snakes. Consequently, a 2001 study found that its venom paralysed fish far more rapidly than other animals, such as snakes and amphisbaenians. This was useful given that fish can rapidly swim away, costing the snake an important meal.
Fish need to be disabled within seconds if they’re to be swallowed, and this is what the aquatic coral snake accomplishes. This species has a heavily neurotoxic venom, causing laboured breathing, paralysis, twitching muscles, slurred speech and potentially death.
As for humans, bites from the aquatic coral snake are extremely rare, as they live in such remote rainforests. However, one case involved an 18 year old boy, who was bitten on the finger with a single fang. Within minutes, a tingling sensation spread up his arm, and he was soon in the emergency room on an artificial ventilator.
Despite these terrifying symptoms, aquatic coral snakes are still considered to be most specialised against fish, so the average eel will probably last just milliseconds.
| 3 | Lotiev’s viper |
Maximum length: 60cm.
This rare viper is one of the most specialised against insects in the world. Lotiev’s viper (Vipera lotievi) lives in extreme southwestern Russia, in the rocky Caucasus mountains close to the border with Georgia. For decades, it was known from just 8 locations, until scientists trudged into the mountains and painstakingly found 70 new locations.
Lotiev’s vipers mainly live on high altitude meadows and rocky talus slopes, and according to a 2007 study, which tested 6 viper species, their venom was the most specialised against insects of the lot. Specifically, they were tested against field crickets, which their venom killed with ease.
After injecting venom, a Lotiev’s viper can immobilise a locust within 6 seconds. It also had the highest proportion of insects in its diet. The likes of common adders and Nicholsky’s adders ate no insects whatsoever, and had no specialisation against them. Orlov’s viper ate a few insects, but was significantly less specialised.
Lotiev’s viper is a mysterious species which is still being mapped out. In 2015, it was discovered in Azerbaijan for the first time ever.
| 4 | Gold-ringed catsnake |
Maximum length: 2.5 metres.
This vivid black and yellow snake lives in the swamp forests of eastern Malaysia, Borneo, and Indonesia. It’s a tree dweller which spends much of its day lazily draped over a branch, with no strong urge to hurt human beings walking past.
Gold-ringed catsnakes (Boiga dendrophilia) particularly favour branches above water, which they dangle over with their tail fastened tightly. This species mainly eats birds, and according to a 2006 study, their venom is highly tailored towards them. They possess a three finger neurotoxin called denmotoxin, which is found in just a handful of Boiga catsnakes.
Though too weak to affect humans, denmotoxin works similarly to a black mamba’s neurotoxins, binding to acetylcholine receptors which receive brain signals. When injected into mice, the ACh blockade was weak and reversible, but in birds, the blockade was “virtually irreversible”. In birds, the effect on neuromuscular transmission was 100-fold stronger than in mice.
Over millions of years, Boiga dendrophilia’s venom has become ultra-targeted against feathered prey. The same is true for several other Boiga catsnakes. The brown tree snake is an invasive species on Guam, and is notorious for decimating the local bird population.
| 5 | Puffing snake |
Maximum length: 275.2cm.
One of the weirder examples, as this species produces two separate toxins which target two separate prey, yet are totally harmless against the other.
Puffing snakes (Spilotes sulphureus) live in South America, and are notorious for raiding birds’ nests, as well as lurking in roofs to ambush bats. This species never uses constriction, and lacks a rapidly injected front fang venom. But they do have enlarged rear fangs, which produce a moderately intense venom, which they laboriously chew in after grabbing their prey manually.
A 2018 study on this species extracted two three-finger neurotoxins, which cause paralysis and laboured breathing. The first was sulditoxin, which was severely deadly against house geckos (Hemidactylus frenatus). When tested against mice, it had no effect, even in quantities 22-fold higher.
The second neurotoxin was sulmotoxin 1, which led to rapid immobilisation of mice, but had no effect on geckos. Both of these toxins are unique to the puffing snake genus (Spilotes).
This study took place in 2018, and until then, puffing snake venom was barely researched at all. It turns out that they’re a super-evolved snake, producing multiple toxins for multiple species. No deaths are confirmed, but who knows – maybe the mixture contains a toxin with our name on it somewhere.
| 6 | Green vine snake |
Maximum length: 216cm.
The green vine snake is a species which perfectly mimics a piece of swinging jungle foliage, aiding and abetting its schemes of ambushing unsuspecting jungle creatures. It’s a widespread species, ranging from southern Mexico through all 7 Central American countries, right into the heart of Brazil.
Green vine snakes measure 1.5-2 metres, and their prey consists of 53.7% lizards and 46.7% birds. A 2021 study analysed its venom, which is only mild in humans and must be chewed in repeatedly to actually take effect. This venom was extremely simple, consisting of just a few toxins, such as a three finger toxin (3FTx) called fulgimotoxin.
In mice and Hemidactylus house geckos, the green vine snake’s venom was only moderately toxic. But in Anolis lizards, which are plentiful in the forests of Central America, the venom’s potency went through the roof.
Several anole species are already confirmed in the green vine snake’s diet: Orton’s anole, the goldenscale anole. Despite their camouflage, green vine snakes often fail at ambushing their alert prey, but this specialised venom increases their chance of success if they do catch hold.
| 7 | Shield-nosed cobra |
Maximum length: 75cm.
The shield-nosed cobra (Aspidelaps scutatus) is one of Africa’s quieter venomous snakes. Though relatively calm, and not inclined to savagely bite interlopers, their venom is highly neurotoxic and has caused several deaths via lung failure.
Shield-nosed cobras measure 40-60cm, and are found in southern Africa, including Zimbabwe, Botswana and South Africa. They stick to the ground, sifting through loose soil, and rarely climbing trees.
In 2020, a study analysed several venomous African snakes. The crude venom of shield-nosed cobras was tested, and found to be far more neurotoxic in lizards compared to other animals. It had a far higher specificity towards reptile acetylcholine receptors, where brain signals are received, compared to mammal ACh receptors.
Shield-nosed cobras have a varied diet, including small mammals and frogs. But first-hand reports suggest that legless lizards are their absolute favourite. With this targeted venom, they can immobilise fast-moving skinks or geckos much more rapidly, allowing them to be swallowed whole without resistance.
Shield-nosed cobras are recognisable by a single massive scale on their nose, which they use to shove aside loose soil like a bulldozer. No dedicated antivenom is available for this small yet potentially lethal snake.
| 8 | Rock rattlesnake |
Maximum length: 82.8cm.
The rock rattlesnake (Crotalus lepidus) takes the phenomenon a step further, and has a venom which varies in specialisation depending on region. This rattlesnake measures just 60-80cm, and lives in Arizona, New Mexico and western Texas. It sticks to remote, rocky desert slopes, and has a relatively mild venom in humans, with no confirmed deaths. In small insects, it’s another story entirely.
A 2017 study tested the Tamaulipan rock rattlesnake subspecies (Crotalus lepidus morulus), a version found exclusively in northern Mexico, and found that its venom was dramatically more potent against house crickets. In the widespread US subspecies (C. l. lepidus), its venom was far more specialised against mice, and less so against crickets.
The mottled rock rattlesnake (C. l. klauberi) is the second US subspecies, and was also stronger against mice, while being the weakest against crickets. But this version was overwhelmingly the most powerful against reptiles, with an LD50 score of 0.17mg versus 1.16mg in C. l. lepidus, the main US subspecies.
The weakest against reptiles was C. l. morulus, the northern Mexican subspecies, scoring just 6.86mg. Each rocky slope has a different prey makeup, forcing the rock rattlesnake to adapt. In humans, rock rattlesnake venom mainly causes swelling and mild haemorrhaging, and is usually survivable.
| 9 | Australian black snakes (Pseudechis) |
Maximum length: 3.2 metres (mulga).
The red-bellied black snake (Pseudechis porphyriacus) causes over 20% of Australian snakebites. It’s infamous for an extremely painful bite, and a host of unpleasant symptoms like nausea, vomiting, haemorrhaging and mild necrosis.
The one mystery is that while this species contains a potent neurotoxin called Eα-Elapitoxin-Ppr1, it has no neurotoxic effects in humans. Human victims tend to experience no paralysis, slurred speech or difficulty breathing.
In 2013, scientists extracted samples of this toxin and a very similar neurotoxin (α-Elapitoxin-Pc1) from its relative, Collett’s black snake. They applied both neurotoxins to avian and rodent nerve-muscle preparations. The verdict was clear, as both had a far stronger effect on the bird tissue. The neurotoxins produced far more twitching in the muscle cell preparations, a commonly used method for testing neurotoxins.
Though Australian black snakes are no joke for mammals, the neurotoxins are one aspect we’re immune to, whether you’re a human being or a giant barn rat. The scientists conclude that “the avian preparation is more sensitive to the neurotoxic effects of these toxins than the mammalian preparation“. Red-bellied black snakes appear all over eastern Australia, sticking close to water bodies rather than dry, arid countryside.
| 10 | Prairie rattlesnake |
Maximum length: 151.5cm.
Prairie rattlesnakes (Crotalus viridis) occupy a swathe of the US mid-west, beginning in southern Canada, ending in northern Mexico, and occupying numerous states inbetween. They reside on the Great Plains and in rocky canyons, rarely appearing in thick forests. Over 90% of their diet consists of mammals, particularly deer mice, squirrels and prairie dogs.
Lizards are barely a feature at all, and a 2023 study identified a toxin tailored specifically towards mammals. It was called myotoxin A, and was originally discovered in 1977. This toxin targets muscle tissue, causing structural damage and necrosis of individual muscle fibres. This can cause chaos in humans, while in small mammals, it’s completely debilitating, causing total paralysis of limbs.
The 2023 study found that myotoxin A was so specialised that it was virtually harmless in lizards. In fact, this was the first ever mammal-specific toxin identified from a rattlesnake.
As a species, prairie rattlesnakes lack neurotoxins, and are most famous for their muscle tissue destruction, which tied in with the new study nicely. They also produce the usual harmorrhaging and swelling, but possess almost no neurotoxins.