Original photo by jo Crebbin/ Shutterstock

Snakes are often pictured curled around a tree in a dense jungle or hiding in a desert waiting to strike some unsuspecting prey. But they’re just as capable in the water as they are on land — in fact, all species of snakes can swim. In North America, a famous example is the cottonmouth (Agkistrodon piscivorus), named for the white color on its mouth that goes on full display when the creature is angry. This snake, native to the southeastern U.S., also goes by the name “water moccasin” because of its predilection for estuaries, bays, and rivers. 

All snakes lay eggs.

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Only about 70% of snakes are oviparous, meaning they lay eggs to produce young. The other 30% give birth, known as ovoviviparity, to snakes encased in an amniotic sac. This is especially true for snakes in cold climates, where eggs wouldn’t survive.

But even going a step beyond the familiar cottonmouth, some 60 species of marine snakes derived from the cobra family call the ocean their home, and monstrously large snakes such as anacondas also spend most of their life in the water. Even snakes that generally have no business in water, such as the desert-loving rattlesnake, can swim in a pinch. Members of the suborder Serpentes (to which all snakes belong) are such good swimmers because their elongated bodies can easily propel them through the water, and some have even evolved tails that look like paddles. But don’t worry, ophidiophobes: It’s not like the Earth’s waters are teeming with snakes. Snakes can’t live in areas that are too cold, and many spots — Alaska, New Zealand, and Ireland, to name a few — are entirely free of them. 

Numbers Don't Lie

Numbers Don't Lie

Average length (in inches) of the Barbados threadsnake, the world’s smallest snake
4.1
Number of snake species as of August 2023, of which 70 or so live in the ocean
4,056
Number of venomous snake species worldwide
600
Number of Americans (out of 10) who fear snakes, the highest number for any phobia
3

The country with the most snake species in the world is ______, followed closely by Brazil.

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The country with the most snake species in the world is Mexico, followed closely by Brazil.

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A small Brazilian island is so jam-packed with serpents, it’s called “Snake Island.”

Located 21 miles off the coast of the Brazilian state of São Paulo is Ilha da Queimada Grande, better known by its nickname, “Snake Island.” Although the island is only 106 acres, it’s absolutely swarming with snakes — specifically, the very venomous golden lancehead (Bothrops insularis). This particular snake is up to five times more venomous than other lancehead species, and its bite is known to “melt” flesh around the impact site. In fact, this golden-hued serpent is so dangerous that the Brazilian government forbids travel to the island except for the occasional scientific excursion. Migratory birds who use the island as a resting spot help sustain this large snake colony, and conservative estimates place the snake population of the place at around 2,000 to 4,000.

Darren Orf
Writer

Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.