Colubridae

Grass Snake (Natrix natrix )

The snakes ( Colubridae ) form with over 1700 species, which are almost 60% of the extant species of snakes, by far the richest family among the snakes. You have, with the exception of the sea, inhabited all habitats available for reptiles and live in temperate, subtropical and tropical regions of Eurasia, Africa, North and South America. Among the snakes there on the ground living, grave border and climbing species. Jewelry tree snakes ( Chrysopelea ) can of gliding tree to tree by spreading their fins, thus converting her entire body an airfoil.

In Germany, Switzerland and Austria six snake species occur. The Aesculapian, smooth snake and the Yellow-green whip snake belong to the authentics snakes ( Colubrinae ). The grass snake, the dice snake and the viper snake are among the water snakes ( Natricinae ). The Yellow Green whip snake and the viper snake do not exist in Germany and Austria. These six snakes vary in appearance by their round pupils from the local poisonous snakes (European viper, viper, asp viper and meadow viper ).

Features

Snakes are mostly slender and long-tailed snakes, whose body is covered with relatively large scales. The head is offset in most cases by the neck and can be long and narrow, but also be short and blunt. The eyes are, except for some burrowing species, large, the pupils are round or oval. The Maul column extends far beyond the eyes. The extra-long at the snakes maxillary bones can not, as with the Vipers, are placed in a vertical position to the facial skeleton. In opistoglyphen species of the family, the so-called illusion snakes, the fangs are in the rear part of the upper jaw, aglyphe or " True snakes ", however, do not have fangs.

Nutrition

Snakes have a rich spectrum of prey, the small mammals, birds, lizards, amphibians, fish, arthropods and molluscs includes. Some snakes are dietary specialists, such as the African and Indian egg-eaters, which feed exclusively on bird eggs.

Toxicity

Most snakes have neither hollow nor grooved fangs. In some species, for example in the grass snake, is located in the saliva a very weak poison that can paralyze small prey, but probably serves primarily the pre-digestion.

The Mirage snakes are no separate taxonomic group, it is rather a series of species within the snakes. You have the rear of the upper jaw grooved fangs, and over the outer furrow the poison is fed with chewing movements into the bite wound of a prey animal. For larger animals, however, deceit snakes are harmless usually, on the one hand by the position of the fangs they do not reach for a bite their victims and on the other the venom of snakes illusion compared to vipers and poison snakes is relatively weak. For individual deceit snake species, such as the Boomslang ( Southern Africa) or the mangrove tree snake ( Southeast Asia ), but the bite can be fatal to humans.

Poison snakes ( Elapidae ) do not belong despite their name to the snakes, but form their own snake family.

Reproduction

Snakes are a few exceptions, such as indigenous to Central Europe smooth snake that is viviparous, oviparous.

System

The systematics of snakes is still the subject of current investigations. So arranged Zaher 1999 based on morphological characteristics nor the next twelve subfamilies to the snakes:

• Boodontinae
• Calamariinae
• Colubrinae
• Dipsadinae
• Homalopsinae
• Natricinae
• Pareatinae
• Psammophiinae
• Pseudoxenodontinae
• Pseudoxyrhophiinae
• Xenodermatinae
• Xenodontinae

Lawson et al. have shown in a first major genetic investigation that a number of these sub-families are more closely related to the poisonous snakes ( Elapidae ), so the corresponding subfamilies Pseudoxyrhophiinae and Psammophiinae have been moved to a new family named Lamprophiidae. Of the original twelve subfamilies according to Zaher the subfamilies Calamariinae, Colubrinae, Pseudoxenodontinae, Natricinae and Dipsadinae in the family of snakes remain. The Xenodontinae and Dipsadinae were distinguished from Cadle, 1985, only because of their distribution area ( South and Central America); the genetic studies show that the relationship of the genera in these subfamilies but not based on the area of ​​distribution. Accordingly, the genera of Xenodontinae have been transferred to the Dipsadinae.

Lawson et al. have also shown that the genera of the subfamily Boodontinae have no common ancestry. The genus Grayia is not one of the Boodontinae, but is the sister genus to the subfamily of authentics snakes ( Colubrinae ). While Lawson et al. they fit into the Colubrinae due to uncertain data able to lead Vidal et al. 2007 for a more detailed analysis of its own subfamily, the Grayiinae one. The remaining genera of the subfamily Boodontinae be placed in the Lamprophiidae and Colubrinae.

Also that the family of vipers ( Viperidae ) are more closely related to snakes than the Pareatinae could Lawson et al. prove. Further investigation of Pyron et al. prove this and also show that the Pareatinae and the vipers are more closely related to snakes than the subfamily even asked Lawson next to the Elapidae Xenodermatinae. The Homalopsinae were Lawson et al. placed as the sister family next to the vipers, Pyron et al. showed, however, due to a broader database that they are adjacent to the formed from Elapidae and Lamprophiidae clade. Accordingly, these three subfamilies were elevated to family rank and are now called Xenodermatidae, Pareatidae and Homalopsidae.

The subfamily Scaphiodontophiinae, consisting only of a formerly to the authentics snakes ( Colubrinae ) scoring genus, was Pyron et al. Introduced in 2010. Their molecular genetic studies showed that the Grayiinae are more closely related than the Colubrinae thus also counted as a subfamily Scaphiodontophiinae.

Outer systematics

The snakes are therefore one of seven families within the superfamily of vipers and viper -like ( Colubroidae ). After pyrone et al. arises within the Colubroidae following system:

Vipers ( Viperidae )

Snakes ( Colubridae )

Poison snakes ( Elapidae )

Lamprophiidae

Water phantom snakes ( Homalopsidae )

Pareatidae

Hump ​​snakes ( Xenodermatidae )

Of the Vipers, the clade, which includes the snakes differs. Due to the lack of solenoglyphs, ie folding, Fangs

Inside systematics

The snakes of the family itself is currently divided into seven subfamilies. The taxonomic position of the individual subfamilies to each other is less well protected than that of the outer system. After pyrone et al. results in the following internal system:

Natricinae

Pseudoxenodontinae

Dipsadinae

Scaphiodontophiinae

Calamariinae

Grayiinae

Actual snakes ( Colubrinae )

The snakes of the subfamily Colubrinae have an asymmetric hemipenis spermaticus with a single sulcus. The Calamariinae differ from other snakes by their bone structure: The eye hole is formed only by the frontal bone and the parasphenoid, the parietal bone is not involved. A diagnostic feature of occurring only in Asia Pseudoxenodontinae is the very deep forked hemipenes. Their sister taxon are the Dipsadinae who live in America and typically have spermaticus a forked sulcus. The water snakes ( Natricinae ) are characterized by a distinctive hemipenis whose sulcus is spermaticus strongly curved.