The viperine water snake or viperine snake (''Natrix maura'') is a semiaquatic, fish-eating natricine water snake. Despite its common names, it is not a member of the subfamily

Viperinae Viperinae, or viperines, are a subfamily of vipers endemic to Europe, Asia and Africa. They are distinguished by their lack of the heat-sensing pit organs that characterize their sister group, the subfamily Crotalinae. Currently, 13 genera are r ...

. It was given its common names due to exhibiting a dorsal colour pattern that superficially resembles that of sympatric

adder ''Vipera berus'', also known as the common European adder Mallow D, Ludwig D, Nilson G (2003). ''True Vipers: Natural History and Toxinology of Old World Vipers''. Malabar, Florida: Krieger Publishing Company. . and the common European viper, ...

species. In comparison to other ''Natrix'' species its head is also somewhat wider and more distinct from the neck. Like most members of the Natricinae it possesses a venom gland on each side of the upper jaw (

Duvernoy's gland The Duvernoy's gland is a gland found in some groups of ''colubridae, colubrid'' snakes. It is distinguished from the venom gland and is not found in ''viperidae, viperids'' or ''elapidae, elapids''. It was named for France, French zoologist Geo ...

) that produces a mild venom that may play a role in swallowing or digestion. The gland is not associated with an enlarged specialized tooth and the venom has to be applied by chewing. The species usually does not bite as a means of defense, and the effect of a bite would be harmless to humans.

Behaviour

The viperine snake looks like an adder and occasionally behaves like one. It is known to strike like an adder, but not to bite. It spends most of its time in water hunting fish, frogs and other aquatic animals. The species is diurnal.UIcnmed.org
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Geographic range

The viperine snake is found in southwestern Europe and northwestern Africa. Specifically, ''N. maura'' is found in the European countries of

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

Andorra Andorra, officially the Principality of Andorra, is a Sovereignty, sovereign landlocked country on the Iberian Peninsula, in the eastern Pyrenees in Southwestern Europe, Andorra–France border, bordered by France to the north and Spain to A ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

, northwestern

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

, and

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

. It has spread to areas of

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

, as well. It is found in African countries of

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

, northern

Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...

, northwestern

Libya Libya, officially the State of Libya, is a country in the Maghreb region of North Africa. It borders the Mediterranean Sea to the north, Egypt to Egypt–Libya border, the east, Sudan to Libya–Sudan border, the southeast, Chad to Chad–L ...

, and northern to central

Tunisia Tunisia, officially the Republic of Tunisia, is a country in the Maghreb region of North Africa. It is bordered by Algeria to the west and southwest, Libya to the southeast, and the Mediterranean Sea to the north and east. Tunisia also shares m ...

. It was introduced to

Mallorca Mallorca, or Majorca, is the largest of the Balearic Islands, which are part of Spain, and the List of islands in the Mediterranean#By area, seventh largest island in the Mediterranean Sea. The capital of the island, Palma, Majorca, Palma, i ...

in the Baleares (not indicated on the distribution map).

Description

''N. maura'' is grey, brown, or reddish dorsally, with a black zigzag vertebral stripe, and lateral series of black ocelli with yellow centers. The labials are yellow with black sutures. It has a diagonal dark band on each temple, and another behind it on each side of the neck. Ventrally, it is yellow or red, checkered with black, or all black. The strongly keeled dorsal scales are arranged in 21 rows. The ventrals are 147–160; the anal plate is divided; and the paired subcaudals number 47–72. Adults may attain a total length of 85 cm (33 inches), with a tail 17 cm (7 inches) long. Boulenger GA. 1893. ''Catalogue of the Snakes in the British Museum (Natural History). Volume I., Containing the Families ... Colubridæ Aglyphæ, part.'' London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 448 pp. + Plates I-XXVIII. (''Tropidonotus viperinus'', pp. 235–237).

Habitat

The viperine snake is found in

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s and

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s, and has also been recorded from areas of brackish water.

Invasion

The species is invasive on Mallorca. ''N. maura'' predates on ''

Pelophylax perezi The Perez's frog (''Pelophylax perezi''), also known as Iberian waterfrog, Iberian green frog or Coruna frog, is a species of frog in the family Ranidae. It is native to southern France, Portugal, Spain, and has been introduced to the Canary a ...

'' among other prey on Mallorca. Research by Moore et al. 2004 suggests

trophic subsidy Trophic, from Ancient Greek τροφικός (''trophikos'') "pertaining to food or nourishment", may refer to: * Trophic cascade * Trophic coherence * Trophic egg * Trophic function * Trophic hormone * Trophic level index * Trophic level * Troph ...

provided by ''P. perezi'' is maintaining higher numbers of the invader than would otherwise occur. ''N. maura'' has altered the behavior of Mallorcan prey. Moore et al. 2004 found that the higher numbers mentioned above are allowing the invader to exert such high pressure that prey species such as the

Majorcan midwife toad The Majorcan midwife toad (''Alytes muletensis'') (also Mallorcan midwife toad or ferreret in Balearic Catalan and Spanish) is a frog in the family Alytidae (formerly Discoglossidae). It is endemic to the Balearic Island of Majorca in the Medite ...

(''Alytes muletensis'') have retreated entirely to habitats too steep for ''N. maura''.

References

External links

Euroherp.com