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Snakes

Temporal range: Early Cretaceous –

Recent, 

112–0Ma

Coast garter snake,

Thamnophis elegans terrestris

Scientific classification

Kingdom: Animalia

Phylum: Chordata

Clade: Sauropsida

Order: Squamata

Clade: Ophidia

Suborder: Serpentes

Linnaeus, 1758

Subgroups

Alethinophidia – Nopcsa, 1923

Scolecophidia – Cope, 1864

Approximate world distribution of snakes, all

species

SnakeFrom Wikipedia, the free encyclopedia

Snakes are elongated, legless, carnivorous reptiles of thesuborder Serpentes that can be distinguished from leglesslizards by their lack of eyelids and external ears. Like allsquamates, snakes are ectothermic, amniote vertebrates

covered in overlapping scales. Many species of snakes haveskulls with many more joints than their lizard ancestors,enabling them to swallow prey much larger than their headswith their highly mobile jaws. To accommodate their narrowbodies, snakes' paired organs (such as kidneys) appear one infront of the other instead of side by side, and most have onlyone functional lung. Some species retain a pelvic girdle with apair of vestigial claws on either side of the cloaca.

Living snakes are found on every continent except Antarctica,in the Pacific and Indian Oceans, and on most smaller landmasses — exceptions include some large islands, such asIreland and New Zealand, and many small islands of the

Atlantic and central Pacific.[1] More than 20 families arecurrently recognized, comprising about 500 genera and about

3,400 species.[2][3] They range in size f rom the tiny, 10 cm-long thread snake to the Reticulated python of up to 8.7

meters (29 ft) in length.[4][5] The fossil species Titanoboa

cerrejonensis was 15 meters (49 ft) long. Snakes are thought

to have evolved from either burrowing or aquatic lizardsduring the mid-Cretaceous period, and the earliest knownfossils date to around 112 Ma ago. The diversity of modernsnakes appeared during the Paleocene period (c 66 to 56 Maago). The oldest preserved descriptions of snakes can befound in the Brooklyn Papyrus.

Most species are nonvenomous and those that have venomuse it primarily to kill and subdue prey rather than for self-defense. Some possess venom potent enough to cause painful

injury or death to humans. Nonvenomous snakes eitherswallow prey alive or kill by constriction.

Contents

1 Etymology2 Evolution

2.1 Origins

3 Distribution4 Taxonomy

4.1 Families5 Biology

PreЄ Є O S D C P T J K PgN

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A phylogenetic overview of the extant groupsModern snakes Scolecophidia

 Leptotyphlopidae

 

5.1 Size5.2 Perception5.3 Skin

5.3.1 Moulting5.4 Skeleton5.5 Internal organs5.6 Teeth5.7 Venom

5.8 Reproduction6 Behavior

6.1 Winter dormancy6.2 Feeding and diet6.3 Locomotion

6.3.1 Lateral undulation6.3.1.1 Terrestrial6.3.1.2 Aquatic

6.3.2 Sidewinding6.3.3 Concertina

6.3.4 Rectilinear6.3.5 Other

7 Interactions with humans7.1 Bite7.2 Snake charmers7.3 Trapping7.4 Consumption7.5 Pets7.6 Symbolism7.7 Religion

7.8 Medicine8 See also9 References10 Further reading11 External links

Etymology

The English word snake comes from Old English snaca, itself from Proto-Germanic *snak-an- (cf.

Germanic Schnake "ring snake", Swedish snok  "grass snake"), from Proto-Indo-European root *(s)nēg-o-

"to crawl", "to creep", which also gave sneak  as well as Sanskrit nāgá "snake".[6] The word ousted adder,

as adder went on to narrow in meaning, though in Old English næddre was the general word for snake.[7]

The other term, serpent , is from French, ultimately from Indo-European *serp- (to creep),[8] which alsogave Ancient Greek hérpō (ἕρπω) "I crawl".

Evolution

The fossilrecord of snakes isrelatively