Reptile
Adder
Britain's only venomous snake
Species group · 9 profiles
Snakes
Nine snake profiles — adder, king cobra, black mamba, pythons and boas. Venom versus constriction, size and range.
Quick answer
Snakes are limbless squamate reptiles; roughly 4,000 living species are described worldwide. This guide profiles nine that illustrate the two main killing methods — venom and constriction — plus familiar wild and captive forms. The set includes the adder (Vipera berus), Britain's only venomous snake, together with king cobra, black mamba, rattlesnake, ball python, boa constrictor, green anaconda, corn snake and garter snake. Length spans under a metre in small colubrids to several metres in large boas and anacondas. Strike speed and venom yield differ sharply among the venomous species. Each profile states venom status, typical adult size, primary diet, geographic range and conservation category.
Snakes in this guide
Reptile
Ball Python
The gentle constrictor that curls into a ball
Reptile
Black Mamba
Africa's fast and feared elapid snake
Reptile
Boa Constrictor
The powerful constricting snake of the Americas
Reptile
Corn Snake
The gentle, colorful beginner's pet snake
Reptile
Garter Snake
One of North America's most common and widespread snakes
Reptile
Green Anaconda
The heaviest snake in the world
Reptile
King Cobra
The world's longest venomous snake
Reptile
Western Diamondback Rattlesnake
The venomous pit viper with a warning rattle
Telling them apart
Venomous snakes inject toxins through fangs; constrictors kill by coiling and tightening until circulation and breathing fail. Many harmless species are misread as dangerous by colour pattern alone. Adders are venomous vipers; ball pythons and boas are non-venomous constrictors. Geography matters in risk assessments: the adder remains the only venomous snake native to Britain, while tropical mambas and cobras occupy a different hazard class.
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Snakes: common questions
What is the difference between venomous and constrictor snakes?
Venomous species deliver toxins through modified fangs; death or immobilisation comes from chemistry. Constrictors coil and squeeze prey until blood flow and breathing stop. Some lineages combine strategies, but the nine profiles here fall cleanly into one camp or the other for practical identification.
Is the adder venomous?
Yes. The adder (Vipera berus) is a venomous viper and the only venomous snake native to Britain. Bites are medically significant but fatalities in healthy adults are rare with prompt care. Adders favour heath, moor and woodland edge across much of Europe and northern Asia.
What is the longest snake?
Reticulated pythons hold verified length records among living snakes, regularly exceeding 5–6 metres (16–20 ft). Among species profiled here, the green anaconda is the heaviest, with large females far bulkier than most pythons of similar length. Exact maxima remain debated in field reports.
Are black mambas the fastest snakes?
Black mambas are among the fastest snakes on land, with short bursts often cited near 20 km/h (12 mph) — far slower than popular myth. Speed aids escape and prey pursuit in African savanna and woodland. Their venom is highly toxic; they are not constrictors.