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Reptiles & amphibians · 15 species guides

Snakes: Vipers, Cobras, Pythons & Identification

Snakes are limbless reptiles in the suborder Serpentes, including vipers, cobras, pythons, boas, mambas, rattlesnakes, sea snakes and grass snakes; they kill by venom or constriction, shed their skin, and are found on every continent except Antarctica.

Scales and body
Snakes lack eyelids and external ears; a single row of wide belly scales (ventrals) is typical. Lizards that look snake-like usually blink or have ear openings.
Head shape
Many vipers have triangular heads from venom glands; elapids such as cobras and mambas are more slender-headed. Head shape alone is not a safety test.
Venom versus constriction
Vipers and cobras inject venom; boas and pythons coil and squeeze. Some species do both poorly or not at all — grass snakes are neither dangerous to people.
Sea snake versus eel
Sea snakes are reptiles with scales and paddle-like tails; eels are fish with gills. Sea snakes surface to breathe.

Snakes are limbless squamates that move by lateral undulation, sidewinding or rectilinear crawling, and that sense prey with tongues, heat pits and vibration as much as with sight. The group spans blind fossorial species the length of a pencil to reticulated pythons that can exceed 6 m. Venomous and non-venomous lineages both matter for identification. Vipers and elapids deliver venom through fangs; boas and pythons kill by constriction. Confusion pairs — adder versus grass snake, cobra versus rat snake, sea snake versus eel — are the practical reason a dedicated type page exists.

Most snake species never threaten people, yet persecution remains a leading cause of local declines wherever fear outruns knowledge. Habitat loss, road kill and the pet trade remove specialists first. Learning the field marks that separate a venomous adder from a harmless grass snake, or a sea snake from an eel, is therefore both a safety skill and a conservation one. This page gathers those marks, then links every WARN snake guide that sits behind the everyday word.

Key facts

  • Snakes are limbless reptiles found on every continent except Antarctica.
  • Vipers and elapids are venomous; boas and pythons kill by constriction.
  • Sea snakes are reptiles, not fish — they surface to breathe air.
  • Most snake species are not dangerous to humans; a small set of families cause almost all serious bites.
  • Habitat loss, persecution and the pet trade are the main modern pressures.
  • Slow-worms are legless lizards, not snakes — they blink and can shed the tail.

How to recognise them

The features that separate this group in the field, in the order they are usually most useful.

Scales and body
Snakes lack eyelids and external ears; a single row of wide belly scales (ventrals) is typical. Lizards that look snake-like usually blink or have ear openings.
Head shape
Many vipers have triangular heads from venom glands; elapids such as cobras and mambas are more slender-headed. Head shape alone is not a safety test.
Venom versus constriction
Vipers and cobras inject venom; boas and pythons coil and squeeze. Some species do both poorly or not at all — grass snakes are neither dangerous to people.
Sea snake versus eel
Sea snakes are reptiles with scales and paddle-like tails; eels are fish with gills. Sea snakes surface to breathe.
The confusion pairs
Adder versus grass snake in Britain: adders have a dark zigzag; grass snakes usually show a yellow collar. Cobra hood versus rat-snake bluff: only cobras flatten a true hood.

15 snakes guides

Search or filter by conservation status. Every guide carries sourced facts, IUCN status and FAQs.

Showing 1-15 of 15 animals

Animal group
A coiled adder (Vipera berus) basking on heathland, its grey-brown body marked with the species' distinctive dark zigzag stripe running down the back and a V-shaped marking on the head.
Least Concern

Reptiles

A

Adder

Vipera berus

Britain's only venomous snake — a shy, cold-tolerant viper marked by an unmistakable zigzag.

United Kingdom · Scandinavia and northern Europe

Open guide
A ball python with brown and gold blotched markings coiled on a wooden surface, head resting on its coils.
Least Concern

Reptiles

B

Ball Python

Python regius (Shaw, 1802)

Africa's gentle 'royal' python — the world's most popular pet snake, bred into thousands of morphs.

West & Central Africa (wild); kept worldwide

Open guide
Boa constrictor with brown saddle markings coiled around a tree branch
Least Concern

Reptiles

B

Boa Constrictor

Boa constrictor

The powerful constricting snake of the Americas

North America · South America

Open guide
A cobra with hood expanded, standing tall on a third of its body length, facing forward with alert posture.
Varies by species

Reptiles

C

Cobra

Multiple elapid genera — Naja (true cobras), Ophiophagus (king cobra) and related hooded species

Hooded elapids of Africa and Asia — iconic, venomous and widely misunderstood.

Africa · Asia

Open guide
Corn snake with orange and red blotched pattern coiled on a wooden surface
Least Concern

Reptiles

C

Corn Snake

Pantherophis guttatus

The gentle, colorful beginner's pet snake

North America

Open guide
Garter snake with yellow stripes along a dark body resting in green grass
Least Concern

Reptiles

G

Garter Snake

Thamnophis sirtalis

One of North America's most common and widespread snakes

North America

Open guide
A grass snake (Natrix natrix) coiled on mossy wood with its head raised, showing the characteristic yellow-and-black collar markings, with green reeds in the background
Least Concern

Reptiles

G

Grass Snake

Natrix helvetica / Natrix natrix

Britain's largest snake — a harmless, water-loving hunter of frogs and toads.

United Kingdom · Continental Europe

Open guide
A massive olive-green Green Anaconda with black oval blotches coiled at the edge of a slow-moving Amazon wetland, its eyes and nostrils set high on the head as it lies half-submerged in dark water
Least Concern

Reptiles

G

Green Anaconda

Eunectes murinus

The heaviest snake on Earth, a silent giant of South America's flooded forests.

Brazil · Colombia

Open guide
Black mamba raised in defensive posture showing pale grey interior of mouth on dry African savanna with scattered acacia
Least Concern

Reptiles

M

Mamba

Genus Dendroaspis — four species of African elapid; black mamba D. polylepis is the largest venomous snake in Africa

Not black — fast, long and elapid; the mamba name covers four species, one legend.

Sub-Saharan Africa · From Senegal and Eritrea south to Namibia and South Africa

Open guide
Paradise flying snake gliding with body flattened into a concave wing between rainforest trees
Least Concern

Reptiles

P

Paradise Flying Snake

Chrysopelea paradisi (Boie & Boie, 1827) — family Colubridae

A snake that glides by flattening its body into a concave wing and undulating in mid-air.

Thailand, Malaysia, Singapore, Indonesia including Borneo and Sumatra

Open guide
A juvenile green tree python (Morelia viridis) with vivid lime-green scales coiled on a rainforest floor among brown dead leaves and forest debris in its natural habitat
Varies by species

Reptiles

P

Python

Family Pythonidae — ~40 species native to Africa, Asia and Australia

Non-venomous constrictors of three continents — powerful, slow and heavily traded.

Africa · Asia

Open guide
A western diamondback rattlesnake (Crotalus atrox) coiled on lichen-covered rock in its natural habitat, showing the characteristic diamond-pattern scales along its back
Varies by species

Reptiles

R

Rattlesnake

Genera Crotalus and Sistrurus — ~36 species in the Americas

Pit vipers of the Americas — rattling warning before the strike.

Americas — United States, Mexico, Central and South America

Open guide
Banded sea snake swimming near a coral reef wall with paddle-shaped tail propelling through clear tropical water
Group page

Reptiles

S

Sea Snake

Subfamily Hydrophiinae — roughly 70 species of fully marine elapid snakes

Elapids that never come ashore — paddle tails, salt glands and venom more potent than most cobras.

Indian Ocean and Pacific Ocean · Tropical and subtropical coastal waters; absent from the Atlantic

Open guide
A non-venomous snake with smooth scales coiled on forest leaf litter, tongue flicking to sample scent.
Varies by species

Reptiles

S

Snake

Suborder Serpentes — ~3,900 species across most continents except Antarctica

Legless reptiles of land and water — diverse, often misunderstood and ecologically vital.

Worldwide except Antarctica, Iceland, Ireland and New Zealand

Open guide
Adder viper coiled on heather moorland with distinctive zigzag dorsal pattern and copper eyes
Family page

Reptiles

V

Viper

Family Viperidae — pit vipers and true vipers; roughly 350 species worldwide

Solitary, heavy-bodied venomous snakes — from adders on British moors to fer-de-lance in Neotropical forest.

Americas, Africa, Europe and Asia · Absent from Australasia and oceanic islands except where introduced

Open guide

Conservation: what this group faces

Snakes are killed out of fear far more often than they injure people. Habitat loss and collection remove specialists first. Accurate identification — venomous versus harmless, snake versus legless lizard — is the starting point for both safety and conservation.

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Snakes: frequently asked questions

What is a snake?
A limbless reptile in the suborder Serpentes, with scales, no eyelids, and a forked tongue used for smell. Snakes include vipers, cobras, pythons, boas and many harmless species.
Are all snakes venomous?
No. Most species are not medically significant to humans. Vipers, elapids such as cobras and mambas, and some sea snakes account for almost all serious bites.
What is the difference between a python and a boa?
Both constrict. Pythons are Old World and typically lay eggs; boas are mainly New World and many give live birth. Exact ranges and scale patterns differ by species.
How do I tell an adder from a grass snake?
In Britain the adder usually shows a dark zigzag along the back; the grass snake is typically olive with a yellow or cream collar and is non-venomous.
Are sea snakes dangerous?
Many have potent venom, but bites on people are uncommon. They are marine reptiles that must surface to breathe, unlike eels.
Are snakes endangered?
Many are. Habitat loss, road kill, persecution and collection for the pet or skin trade threaten numerous species, while others remain common.

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