Snakes

Snakes fact file

• Snake facts
• Snake range
• Snake characteristics
• Snake conservation
• Snake news
• Snakes in culture
• Popular snake videos
• Glossary

Snake facts

• There are nearly 3,000 species of snake in the world.
• Only around 375 snake species are venomous, and only a small proportion of these are potentially harmful to humans.
• All snakes are carnivorous.
• Most snake species have only one functional lung.
• Snakes have no eyelids or external ears.
• With its highly toxic venom, the inland taipan (Oxyuranus microlepidotus) is believed to be the world’s deadliest snake. One bite contains enough venom to kill 100 men.
• The longest living snake, the reticulated python (Python reticulatus), can grow to over ten metres long.
• The largest ever snake was the Titanoboa which lived 60 million years ago and would have measured up to 15 metres long.
• The smallest snake in the world is the Barbados threadsnake (Leptotyphlops carlae), growing to around four inches. This species was only discovered as recently as 2008.
• The snake with the longest fangs is the gaboon viper (Bitis gabonica), with fangs of up to 50 millimetres in length.
• The black mamba (Dendroaspis polylepis) is considered to be one of the fastest snakes in the world, reaching speeds of up to 20 kilometres an hour.
• Spitting cobras can spit venom up to about eight feet using a specially modified fang.
• The boa constrictor is the only living animal whose common name is the same as its binomial scientific name.

Snake range

Snakes have an extremely large global distribution. Although snakes are most numerous in warm, tropical regions, they are found on every continent except Antarctica. One species, the adder (Vipera berus), is even found within the Arctic Circle. There are however a number of snake-free islands, including Ireland, Iceland and New Zealand.

Snake characteristics

Snakes are specialised limbless reptiles, most closely related to lizards. Ranging in size from around ten centimetres to over ten metres, snake body shape and length varies greatly depending on each species’ lifestyle and diet. Snakes are found in a wide range of different habitats and are able to move over land, climb, swim or burrow with ease.

Snakes typically have poor eyesight and hearing but are able to detect their surroundings using other senses. By flicking its tongue, a snake is able to pick up scent molecules which are analyzed using a special organ known as Jacobson’s organ. Some species have heat sensitive pits in the scales around their mouth which can help them to detect warm-blooded prey.

Snake skin is covered in separate scales and topped with a tough layer of keratin for added protection. As this keratin can become worn or damaged and does not allow for growth, snakes must shed their skin from time to time. Snakes typically shed most often when they are young, and also after hibernation and before and after giving birth or laying eggs. Unlike lizards, snakes shed their skin in one piece, including the eye caps. Check out this video of a grass snake (Natrix natrix) shedding its skin.

All snakes are carnivorous, and are skilful predators which feed on prey ranging from small insects to crocodiles. Some snakes actively chase prey while others use stealth to ambush their unsuspecting victims. Small prey can often be swallowed alive and whole, but when tackling larger animals, snakes may employ a venomous bite or constricting embrace to subdue or kill their quarry before it is consumed.

Snakes are well known for their ability to swallow large prey, thanks to their inward pointing teeth, unfused lower jaw and extremely flexible skin. Eating such large meals means that some species need to feed less than once a month, and some pythons and boas can survive for a year or more without eating.

Although venomous snakes are among the most famous and the most feared, only a small proportion of snakes are actually venomous, and many of these pose no threat to humans. Snakes are reactive rather than aggressive and will typically only bite when threatened. Venom comprises of modified digestive juices that not only subdue or paralyze the prey animal, but also begin to digest it, breaking down the skin and internal organs. Some species of snake use venom defensively, such as the Mozambique spitting cobra (Naja mossambica).

While most snakes lay eggs, there are also a number of species which give birth to live young. Although very few snake species show any level of parental care, there are a small number of species such as pythons, in which the female will coil around the eggs to guard them from predators and possibly help to incubate them too. Although nearly all snakes reproduce sexually, there are a few which can reproduce through parthenogenesis, meaning that all members of the species are female and have hatched from unfertilised eggs. One such example is the Brahminy blind snake (Ramphotyphlops braminus).

Snake conservation

Globally speaking, one of the biggest threats facing snakes and indeed many other species is habitat loss, as the expanding human population constantly requires additional space and resources. In addition to this, the introduction of predatory species into a snake’s habitat can have devastating consequences, as seen in the case of the Antiguan racer (Alsophis antiguae). Snakes are also collected for their skin, for meat or for pet trade, and sometimes snakes may simply be exterminated by local people who are afraid of them.

There are a number of methods used to help conserve snakes. Habitat can be protected through the creation of nature reserves and national parks, and outreach programs can help to educate people and overcome prejudice towards snakes. Snakes can also be bred in captivity, although this may sometimes prove difficult and success may be limited.

Find out more about the conservation of snakes and other reptiles:

• International Reptile Conservation Foundation
• IUCN SSC Amphibians and Reptiles specialist groups

Snake news

Snakes in culture

Snakes feature heavily in myths, legends, folklore and even religion. In the Hindi language the snake is known as ‘nag’, and is worshipped across much of India, and the Indian God Lord Shiva is always pictured with a cobra around his neck.

In Chinese culture, the 10th February 2013 marks the start of the Year of the Snake. The snake is the sixth of twelve animals featured in the Chinese Zodiac, and it is said that according to ancient Chinese wisdom, a snake in the house is seen as a good omen and a sign that the family will not go hungry. Those born in the year of the snake are said to be wise, calm and responsible.

To celebrate the Chinese Year of the Snake, check out our fortune cookies on Facebook and join in with our daily snake hunt on Twitter.

Sadly, in many cultures, the snake has been unfairly burdened with a very negative reputation. This has led to years of persecution by humans who misguidedly perceive snakes as dangerous and threatening. The irrational fear of snakes is known as ophidiophobia.

Popular snake videos

Glossary

Jacobson's organ

An organ located in the roof of the mouth in many vertebrates (animals with a backbone) that can detect certain chemicals. Also known as the vomeronasal organ.

Keratin

A group of fibrous proteins that form the basis of hair, nails, wool etc in animals.

Parthenogenesis

The development of offspring from unfertilised eggs. The individuals that results are usually genetically identical to their mother.

Nocturnal

Active at night.