| 1 | Puff adder |
Maximum length: 191cm.
Location: almost of sub-Saharan Africa.
In Africa, Bitis is a large genus of venomous vipers which has endless different forms. Some live in a single rugged mountain range, while others patrol shrubland and desert. The Bitis genus has 18 confirmed members, and the puff adder (Bitis arietans) is overwhelmingly the most common. This may be the most common venomous snake in all of Africa, as it inhabits almost every sub-Saharan country, plus Saudi Arabia and Oman.
Puff adders measure 1-1.5 metres, and have a thick, stubby body. They’re mainly an ambush snake, lurking in knee high thickets, waiting for rodents (their main prey) such as four-striped grass mice to wander pass.
With such a thick body, this species can kill a rodent with its crushing weight alone, but their main power is a corrosive venom. Puff adders have a mainly cytotoxic venom profile, which causes severe swelling, necrosis and typically leaves victims alive, but with deformities and possibly amputations.
Puff adders have various skills: they’re strong swimmers, disguise their own chemical scent, and can produce 156 babies at once. Combined with their flexible habitats, including forests, grassland and savannah, this has allowed them to take over most of Africa. Despite the black mamba’s nightmarish reputation, the puff adder is believed to top Africa’s annual snakebite rankings.
| 2 | Gaboon adder |
Maximum length: 175cm.
Location: central Africa.
The second most widespread Bitis adder in Africa. Gaboon adders aren’t as common as the puff adder, but in many respects, they’re a more finely tuned and efficient snake machine.
Gaboon adders (Bitis gabonica) are found in countries such as Uganda, Tanzania, Kenya, Zambia, as far west as Nigeria. They’re an absolute tank of a snake, which not only blast through the 1.5 metre mark with ease, but have an extremely thick body, particularly for a snake which isn’t a constrictor. They’re the heaviest snake in Africa, and one of the heaviest worldwide, joining the eastern diamondback rattlesnake. Their fangs hold the global record for length, maxing out at 5.5cm (2.2 inches).
Then there’s their camouflage. A puff adder’s beige shades blend superbly with thickets, but gaboon adders take it to the next level, with segmented patterns that mimic leaves perfectly. No snake of such bulk and size has as effective a camouflage, as this snake can be virtually invisible on a Ugandan forest floor.
Gaboon adders mainly inhabit woodlands and forests edges, plus tea and coffee plantations. This is another dangerously venomous snake, as yet another global record is for the highest recorded venom yield, with 2400mg recorded in one experiment. As with the puff adder, gaboon adders produce very neurotoxins, and mainly cause local tissue destruction.
| 3 | Horned adder |
Maximum length: 52.3cm (wild), 60.0cm (captivity).
Location: southern Africa.
This 30-40cm viper lives further south, where it has a large range, including South Africa, Namibia, Mozambique and Zimbabwe. Horned adders (Bitis caudalis) are encountered commonly by ordinary Africans, and mainly favour dry areas, such as semi desert, dry shrubland and the bottoms of rocky canyons.
This member has two classic physical features, the first being a single horn above each eye, which is actually a single extended and sharpened scale. The second is a huge variety in colour, which fits with each location. Those in rockier arid country are grey, while those in the sandy Namib desert have reddish-beige shades.
Lizards are their main prey, including the bushveld lizard (Heliobolus lugubris), but horned vipers also eat plenty of rodents. This is one of the shorter Bitis species, but only a fool would confuse diminutiveness with timidness. When cornered, the horned adder will strike without thinking, beginning by coiling into a Z shape, with their head tilted back slightly. They keep their mouths gaped and their fangs visible, and lunge so forcefully that their entire body can be lifted off the ground.
Estimates on the toxicity vary, with an LD50 score ranging from 0.15-1.2mg. However, both of these well outstrip a cottonmouth (2.04mg). The venom yield was estimated at 85mg per bite, which is respectable for such a small snake. Confirmed symptoms include nausea, vomiting, severe pain, and agonising blistering and necrosis around the bite site.
| 4 | Southern adder |
Maximum length: 42cm.
Location: a tiny pocket of South Africa.
While puff adders control almost the entire continent, the southern adder (Bitis armata) has been pushed back to one narrow corner. This species resides in just one country: South Africa, and only then the extreme southwest.
Southern adders can be found in the countryside surrounding Cape Town, normally in heathland or shrubland with an abundance of limestone rock. This is a steely-grey species, which is highly proficient at blending into bare rock. Southern adders also love to hide in thick grass tussocks, and prefer moister environments to the dust-loving horned adder.
Very little is known about the venom of this species, and there are no detailed case studies. However, a 2020 study did discover several postsynaptic neurotoxins. Whether these are powerful enough to paralyse a human victim, or even cause slurred speech and twitching eyelids, is a mystery, but the berg adder is similarly sized and more than capable of causing chaos in human brain signals.
The southern adder is a horned species, yet these look more like solid tufts of hair, eyelashes which went wrong. Much of their South African habitat has been destroyed, and they’re now listed as vulnerable by the IUCN. They might be poorly researched, but give this snake a wide berth, just like all Bitis adders.
| 5 | Berg adder |
Maximum length: 60cm.
Location: South Africa, Zimbabwe.
The most likely Bitis viper to stumble across in the mountain ranges of southern Africa. Berg adders (Bitis atropos) are mostly found in South Africa, but also Zimbabwe, Mozambique, and the tiny nations of Lesotho and Eswatini. The Drakensburg mountains are one of their hotspots, where this adventurer found them to be the second most common snake.
Berg adders appear in Zimbabwe at altitudes up to 3000 metres, and usually above 1500 metres. This is a high altitude species which will never be found in cities like Johannesburg or a dusty desert in southern Namibia. Berg adders like moist areas with plenty of long grasses and rocks to bask on in the sun, often right next to hiking trails.
Unlike the puff adder, berg adders have one of the most neurotoxic venoms of the entire Bitis genus. One highly detailed study documented 14 bites from 1987 to 2003. All experienced local cytotoxic effects, and in 13, the symptoms became systemic. These included altered taste, drooping eyelids, visual disturbances, and swallowing difficulties (dysphagia).
Most disturbingly, 10/13 patients experienced respiratory failure. All of these are connected to disruption of brain signals, and one of the patients, a 42 year old man, was hospitalised for 114 days. This Bitis member packs a lot of punch for being so small.
| 6 | Namaqua dwarf adder |
Maximum length: 27.6cm.
Location: Namibia, Namaqualand (South Africa).
A tiny adder which reaches a maximum of just 27.6cm. Namaqua dwarf adders live a harsh life, dwelling solely in the bone dry deserts of southwest Africa, particularly in the Namib desert. They thrive on sand dunes, which they traverse using a rare sidewinding locomotion. Namaqua dwarf adders are nearly always a sandy beige, which gives them immense camofuage in their parched biomes, and allows them to use their favoured hunting strategy: ambush.
This viper prefers to flee rather than fight, but when cornered, they’ll hiss loudly, and make a mixture of dummy and all too real strikes. Their venom causes mainly local symptoms, like swelling, discoloration and oozing pus. Namaqua dwarf adders are not just the smallest Bitis member, but the smallest confirmed viper worldwide, out of 250 species.
Living in such parched landscapes, Namaqua dwarf adders have very poor survival rates, just 39-56% per annum, which is far lower than other vipers. This is a generalist feeder, which must eat whatever the unforgiving desert offers them. Their favourite prey is Knox’s desert lizard (Meroles knoxii), followed by the Namaqua rain frog and Austen’s thick-toed gecko.
| 7 | Ethiopian mountain adder |
Maximum length: 130cm (so far).
Location: only Ethiopia.
A Bitis viper found only in Ethiopian mountain ranges, usually at altitudes of 1700-2800 metres.The Ethiopian mountain adder (Bitis parviocula) was first discovered in 1977, and is a mysterious snake whose lifestyle has barely been studied. At a current record of 130cm, this is one of the longer Bitis adders in Africa.
Within their Ethiopian mountain kingdom, this species seem to pop up anywhere. One was found in grassland by a small stream, another in long grasses outside a brewery, and another in a forest clearing by an old coffee plantation.
It’s theorised that Bitis parviocula kills several Ethiopian people each year, but before 2011, the venom’s properties were completely unknown. That year, a study compared Bitis parviocula venom to puff adder venom. It found a slightly weaker LD50 score of 1.56mg, versus 1.35mg in mice.
But the minimum haemorrhagic dose, the quantity required to create a 10mm circular ring of haemorrhaging, was significantly lower, at 0.88mg versus 1.7mg for puff adders. Keepers testify that Ethiopian mountain adders have a milder temperament, but react furiously if touched or provoked in any way.
| 8 | Red adder |
Maximum length: 43.4cm, possibly 44cm.
Location: western South Africa.
The red adder is found exclusively in South Africa, with no crossover into Namibia. This is mainly a neurotoxic adder, which is small, and slithers with fast, jerky movements. The red adder (Bitis rubida) is a highly variable species, as some are red as promised, but others are grey, or a more typical viper beige. Another chunk have black and white shades like a 1940s film.
The red adder was only discovered in 1997, at which point it was already deemed to be threatened by habitat loss. Red adders generally live in mountainous areas, and in western South Africa, they can sometimes be found side by side with horned adders (Bitis caudalis). However, they never appear alongside the southern adder (Bitis armata), which only appears in coastal regions of the Southern Cape.
At 30-40cm, this is another short viper, although not tiny like the Namaqua dwarf adder. In 2013, a pregnant red adder was captured hiding beneath rocks. She measured 43.4cm, and soon gave birth to 11 healthy babies (live young). These ranged from 14.5-15.8cm.
| 9 | Rhinoceros viper |
Maximum length: 205cm.
Location: west Africa.
A chunk brute of a snake, which can reach 2 metres, and appears in the forests of Ivory Coast, Togo, Liberia, Sierra Leone and other western African nations. This species is most closely related to the gaboon viper, but is separated by two small “horns”. These are located above its nose, rather than above the eyes like with the South African horned adder
Rhinoceros vipers (Bitis rhinoceros) are dangerously venomous, but lack neurotoxins, mainly causing tissue chaos like necrosis and tissue swelling. They have immense camouflage due to their complex patterns, but unique scale microstructures also add to this disguise. Analysis reveals that each black scale has a series of leaf-like microstructures and nano ridges, which increases light absorption compared to non-black scales, while causing light reflectance to plummet 4 fold.
Like other Bitis adders, rhinoceros vipers are mainly ambush predators. According to a 2008 study, monkeys fear them just as much as we do. Sooty mangabey monkeys were followed for 429 days, during which time they crossed paths with rhinoceros vipers 43 times. In each encounter, they responded with loud cries and alarms. Interestingly, this monkey species shows no fear of forest cobras, probably because they’re too thin-bodied to eat them.
| 10 | Many-horned adder |
Maximum length: 75cm.
Location: extreme southwest Africa.
A neighbour of the horned adder, which is encountered much less frequently. Many-horned adders (Bitis cornuta) are found in two countries: western South Africa (Namaqualand) and southern Namibia over the border. They average at 30-50cm, and the all time record was 75cm, for an individual raised in captivity.
Though many-horned adders vary in colour, this isn’t as extreme as with their neighbour Bitis caudalis. They have consistent dark rectangular blotches, and the colour beneath is typically grey, sometimes reddish-brown.
One glance at the image above tells you everything: Bitis cornuta has perhaps the most complex “horns” of any snake alive. Rather than sharp and straight, they look like jagged sets of horns giving birth to all-new sets of horns.
Exactly why they developed is a mystery. It may be as simple as intimidation, causing an ever-accelerating arms race whereby the snake with the craziest horns won. Many-horned adders prefer drier areas, including rocky semi-deserts, but can also be found in heathland on mountainous slopes.
One study tested 5 members of the Bitis genus. Horned adders (Bitis caudalis) had an extremely indiscriminate venom, with coagulant activities against mammals, lizards, amphibians and birds alike, but the many-horned adder only affected mammals and birds. Its venom had powerful anticoagulant activity, destroying clotting agents like fibrogenin so that blood flows freely. Many-horned adders have a nervous disposition, and will strike if they feel slightly threatened.
| 11 | Desert mountain adder |
Maximum length: 61cm.
Location: extreme southwest Africa (a tiny area).
An aggressive adder, which lunges and strikes at humans who disturb it, but a relatively rare one. The desert mountain adder (Bitis xeropaga) is found in a small area straddling the borders of Namibia and western South Africa.
This is poorly researched viper, with little information about its venom or toxins. This species is mainly found on dry mountainous slopes and rocky plains, where it often vanishes into dark cracks, searching for reptile prey, and sheltering from the sun. This species poses a huge threat to overconfident explorers mindlessly reaching their arms into dark crevices.
The desert mountain adder overlaps with two other adders of this list, the horned adder and many-horned adder. In terms of patterns, it’s easily confused, with a nearly identical grey-beige colour. One feature is that Bitis xeropaga nearly always has neat encircling bands. Each of these bands contains a dark portion, followed by a lighter portion before the dark returns.
A difference to other Bitis members is that generally, the bands are more orderly and straighter in the desert mountain adder, while in the horned adder, for example, they’re much more haphazard, but even these rules aren’t fully consistent. Luckily, there’s one ID feature you can always rely on – the desert mountain adder has no horns. This easily distinguishes it from the two Bitis adders it coexists with.