| 1 | Atractus (ground snakes) |
Members: 141.
There are over 3900 snakes as of 2024, divided into 520 groups, or genera. A large handful have just one member, like Ophiophagous, which the king cobra belongs to (Ophiophagous hannah). Then there’s genera which are enormous, and the largest of all is the Atractus genus, which are almost uniformly shy and harmless. This is a burrowing snake family which isn’t fully blind and fossorial like a blind snake, yet spends a significant portion of its time underground. There’s currently 141 species, and all but 5 live in South America, with those rare exceptions appearing in Panama, one being Atractus imperfectus.
New Atractus members are being discovered almost each year. Three were found in Ecuador in 2022, including Atractus discovery, and one in 2023 from the Peruvian Andes, Atractus paulus. Their shy ways mean that they avoid scientists, unlike a tiger ratsnake which is always racing around, or a boa constrictor, which is so huge they cannot be missed. Atractus members lurk quietly below everyone’s radar, where they particularly feed on earthworms, and sometimes insects. One characteristic of Atractus is a mouth with a relatively small gape width.
Being unadventurous snakes which stick to one neighbourhood, this family has had endless, small segmented territories in South America where new species can develop. One of the most common is the broad-headed ground snake (Atractis latifrons), found across a swathe of Amazonian Brazil. Near Sau Paulo, Atractus pantostictus or the fura-terra is the most common.
| 2 | Oligodon (kukri snakes) |
Members: 88.
A huge family of southeast Asia and the Indian subcontinent, which typically measures 50-100cm. The 88 kukri snake members are united by common characteristics: an extremely mild venom which is incapable of killing a human, but unusually sharp front fangs that can easily draw blood with a slashing wound. The family’s name originated from the kukri knives wielded by Nepalese Gurkha soldiers.
This family sticks to the ground rather than jumping between branches, though they may climb low bushes in pursuit of prey. Two of the most common species are the banded kukri snake (India, Sri Lanka) and small-banded kukri snake (Thailand, Cambodia). Kukri snakes cover an enormous amount of space. At the extreme west, you have the streaked kukri snake (Oligdon taeniolatus), which reaches Pakistan. At the opposite extreme, you have Forbe’s kukri snake, which lives on Indonesian islands not far from Australia, though no members reach Australia itself. This family thrives in warmth and humidity. To the northeast, kukri snakes just reach Shanghai, but fail to get near the Korean peninsular, let alone Japan.
Thailand lies at the epicentre of the kukri snake empire, with 21 confirmed species as of February 2024. The most recently discovered member is Oligodon churahensis, found in 2021, after scientists noticed an unusual-looking snake in an Instagram post, found in India’s Himachal Pradesh.
| 3 | Micrurus (coral snakes |
Members: 82.
The most numerous genus of venomous snakes. The Agkistrodon family of cottonmouths and copperheads numbers just 8, but coral snakes have swollen to 82, the most recent addition being the Brazilian Micrurus boicora in 2020.
As a whole, the Micrurus family is extremely lethal. The vast majority have neurotoxins, capable of paralysing muscles and triggering respiratory paralysis in a few measly milligrams. But due to their shy personalities, Micrurus coral snakes cause very few deaths overall, compared to cobras or lanceheads. The deadliest is probably the painted coral snake, found near Sao Paulo, but this still caused just 36 officially recorded bites from 1867 to 2014.
Coral snakes generally shun open spaces, with the vast majority favouring leafy forest floors, with a few exceptions like the aquatic coral snake. Some members can be impossible to distinguish for a layman. The USA has two Micrurus members, the eastern and Texas coral snakes, and the main difference is that the black ring edges slightly further up the Texas coral snake’s neck.
Micrurus is the family of true coral snakes. This genus only inhabits the Americas, as others abroad belong to Calliophis, like Malaysian blue coral snakes, or Sinomicrurus, like MacLelland’s coral snake (Thailand). Primitive Micrurus fossils have been found in Nebraska dating back 16.0–13.6 million years.
| 4 | Lycodon (wolf snakes) |
Members: 73.
An enormous Asian family, which lacks any venom and kills its prey via constriction. Wolf snakes are a flexible group, which normally stick to the ground, but inhabit forests, fields, beaches, and farmyards alike. They often invade people’s homes, and bite fiercely if pushed, and some can flip onto their backs and play dead.
The wolf snakes cover a similar range to kukri snakes overall: southeast Asia and the Indian subcontinent. Yet despite numbering 15 fewer species, they’re even more widespread. They have colonies in South Korea and Japan, in the form of the red-banded snake and oriental odd-toothed snake respectively. Again, they don’t quite reach Australia; the closest species is the common wolf snake (Lycodon capucinus). The most extreme northwesterly species is the MacKinnon’s wolf snake, which inhabits the outskirts of Islamabad.
Of the 72, the two most common species are the Indian wolf snake, which control India, Bangladesh and Sri Lanka, and the common wolf snake, which controls Thailand, Indonesia and other southeast Asian realms. The newest species discovered was Lycodon cathaya from southern China, found in 2020.
| 5 | Tantilla (centipede snakes) |
Members: 68.
Another shy family, which isn’t a blind snake, but shares their habits like lurking under leaf litter and soil, and mainly appearing post heavy rains. As the name suggests, the Tantilla genus mainly feeds on centipedes, unlike earthworms for Atractus. The black-headed snakes are an alternative name. The USA has 6 species, 4 in Texas and Arizona, but 2 are stranded in Florida and are seriously endangered, especially the rim-crowned rock snake (Tantilla oolitica).
The Tantilla family is completely harmless, with no venom. The most northerly of the 68 species is the plains black-headed snake, which reaches southeastern Wyoming. The most southerly of all is the black headed snake (Tantilla melanocephala), which reaches Argentina. The latter might be the most common Tantilla overall, as it covers a huge swathe of Brazil.
Being so small, Tantilla members fall to many grisly fates, like being trapped in black widow webs, or swallowed by greedy false coral snakes. Across the Americas, there’s a wonderland of red, black and white Tantilla members, but all are united by being shy and lurking under cover. Like the Atractus genus, being so shy keeps them hidden from researchers, meaning that there’s almost certainly more waiting out there to be discovered.
| 6 | Calamaria (reed snakes) |
Members: 66.
The Calamaria reed snake family is less widespread than the kukri or wolf snakes, but still manages to have 66 members. The northernmost is the northern reed snake found near Shanghai, while the southernmost live in Java, including Linne’s dwarf snake, which is extremely common near Jakarta.
The Calamaria genus is mainly nocturnal, lurking under shelter by day. This is a small, burrowing group averaging at 20-50cm long. They might be the largest consistently iridescent family, producing shimmering rainbow colours under bright lights. Their ordinary colours aren’t too shabby either, with snowy white heads, vibrant lava stripes, blue bands, or sometimes a more boring consistent black. Reed snakes are united by a tube-shaped head with little neck, round pupils, and no dangerous venom.
Few species of this genus are well researched. Earthworms are confirmed prey in several species, like white-bellied reed snakes, pink-headed reed snakes and variable reed snakes. The latter two are some of the most widespread in the family. Then there’s the collared reed snake, which is extremely abundant on Taiwan, and encountered by ordinary people much more often than normal. This is now our third all-powerful genus of shy burrowers; the king cobra should take note.
| 7 | Dipsas (snail-eaters) |
Members: 55.
Tied for 7th position, we have the largest snail-eating family, Dipsas, which beats the Sibon snail eaters of South America (22 members), as well as the Pareas snail eaters of southeast Asia (30).
Dipsas members typically live in humid forests, from lowland rainforests to high altitude cloud forests, where they cling to branches 0.5-3 metres high, and keep a keen eye out for snails slithering along. The most common is probably Dipsas indica, the neotropical snail eater, which covers a swathe of Brazil. The most southerly is the Bolivian snail eater, found in Argentina’s Buenos Aires province, while the closest to the USA is Gaige’s thirst snail-eater (southwest Mexico). They can also appear in human-modified zones, resting on fences or even barbed wire.
Dipsas snakes first discover a snail or slug by finding a mucous trail, inspecting and licking at the ground (or branch). They follow the trail, then attack the snail’s shell with their mouth, and wrap an entire body coil around the hard calcified armour. Then they use a specialised jaw to suck them free, with alternating mandibular retractions. Once swallowing is complete, they wipe their face on the ground to remove any slime.
That said, this diet isn’t uniform. A study from central Panama found that among the nearby Dipsas, which could have included 4 species, earthworms actually contributed by far the majority of prey. The Argus goo eater feeds mainly on frog spawn rather than snails, greedily lapping up the orange goo stashes from crevices on fences or nooks in branches. Probably the most consistent feature in the Dipsas family is their large round eyes. Their heads are larger than their necks, rather than a continuous tube like a coral snake. Dipsas members range from 30-110cm and are often preyed on by coral snakes.
| 7 | Erythrolampus (false coral snakes) |
Members: 55.
The Erythrolamprus family occupies most of South America, plus central America as far north as Guatemala, the most northerly being Erythrolamprus bizona. This is an incredibly diverse family, so much that it seems odd that they’re all related. While dubbed the false coral snakes, a good 50% don’t appear to mimic coral snakes, like the velvet swamp snake, which is often a bright green or blue. Even their diets are diverse: E. bizona in central America feeds on snakes, while the royal marsh snake (E. reginae) eats 95% amphibians, including frogs’ eggs. But one feature they do share is horizontal neck flattening, enlarging sideways like a cobra to appear larger.
Likewise, the vast majority are moderately venomous. This is a rear-fanged family which must chew victims repeatedly, yet as a group, they have one of the most underestimated venoms. A bite from a yellow-bellied liophis (Erythrolamprus poecilogyrus) near Rio Grande in 2010 resulted in the victim having muscular pain up his entire arm for 5 days, which became worse when the muscles were flexed. Aesculapian false coral snakes can cause the entire arm to swell up.
Many of its members originally belonged to Liophis, and a big chunk were handed to Erythrolamprus all at once when that genus was dissolved. Some are still called the liophis colloquially, like the yellow-bellied liophis. The most southerly member is the arrow ground snake (E. sagittifer), which plunges deep into Argentina, while the newest species is E. aenigma, discovered in the northern Brazilian savannahs in 2021.
| 9 | Geophis (Latin American earth snakes) |
Members: 54.
The Geophis genus covers the smallest geographical area of our list, but still numbers 54 independent species, which are all non-venomous. Being small and secretive means they need less land to roam about in compared to larger rattlesnakes. The vast majority are found in central America, plus Mexico, with a few spilling into Colombia, but none entering Brazil.
The Geophis are a varied bunch. Some are shy burrowing snakes which eat slugs and earthworms (Hoffman’s earth snake), while others are committed snail suckers like the Dipsas family. Some have small, beady black eyes, while others have large, bulbous detailed eyes for scanning branches for snails. Some have bulkier heads, while the Colombian earth snake’s head is narrow for digging into soft soils. Nevertheless, all are harmless to humans, and can usually be picked up safely.
Some Geophis members are incredibly rare. The Dunn’s earth snake of Nicaragua was found once in 1932, and never again since. The Colombian earth snake lies the furthest south, while Dugès’ earth snake lies closest to the US border, reaching northern Mexico. Overall, the most commonly encountered member by ordinary people is the terrestrial snail sucker (Geophis sartorii).
| 10 | Crotalus (rattlesnakes) |
Members: 53.
Among dangerously venomous snakes, the second most plentiful genus is the Crotalus family of true rattlesnakes. This isn’t even including the Sistrurus family, which contains massasaugas and pygmy rattlesnakes. The USA has 20 rattlesnakes, and then the dusty badlands of Mexico have about 30 more. The most southerly species is the South American rattlesnake (Crotalus durissus), found as far south as Argentina, and this likely contains multiple hidden species.
In fact, the Crotalus rattlesnakes have the largest north to south range of any genus on this list. The most northerly is either the Pacific rattlesnake or prairie rattlesnake, which both inhabit southwest Canada. Every single rattlesnake is dangerously venomous, though some are far milder than others. The majority are haemotoxic and cytotoxic, triggering swelling and spontaneous bleeding, or kidney failure in the largest species like the diamondbacks. A small subgroup are neurotoxic, causing paralysis – this includes the tiger, Mojave, and South American rattlesnakes.
The longest of the 53 is the east diamondback rattlesnake (record: 251.5cm), followed by the west diamondback, and the Mexican west coast rattlesnake (Crotalus basiliscus). The vast majority prey on mammals and lizards, in varying ratios. Amphibians and fellow snakes are rare prey for rattlesnakes.