Adders
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Grass snake ( Natrix natrix ) |
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| Colubridae | ||||||||||||
| Oppel , 1811 |
The snakes (Colubridae), from Middle High German nāter (“Natter”, also “snake”), form with over 1700 species , that is almost 60% of the snake species living today, the most species-rich family among snakes by far . With the exception of the sea, they have colonized all biotopes accessible to reptiles and live in temperate, subtropical and tropical regions of Eurasia , Africa , North and South America . Among the snakes there are species that live, dig and climb on the ground. Ornamental tree snakes ( Chrysopelea ) can glide from tree to tree by spreading their ribs and thus making a wing out of their entire body.
There are seven species of adder in Germany, Switzerland and Austria. The Aesculapian snake , the smooth snake and the yellow-green wrath snake belong to the real snake (Colubrinae). The grass snake , the bullion grass snake , the species status in 2017 was awarded, the dice snake and viper snakes belong to the water snakes (Natricinae). The yellow-green angry snake and the viper snake do not occur in Germany or Austria. Outwardly, these seven adders differ from the native venomous snakes ( European horned viper , adder , aspic viper and meadow viper ) by their round pupils .
features
Adders are predominantly slender and long-tailed snakes whose bodies are covered by relatively large scales. In most cases the head is separated from the neck and can be long and narrow, but also short and blunt. Except in some burrowing species, the eyes are large, the pupils are round or oval. The gap in the mouth extends far behind the eyes. The maxillary bones of the snakes, which are particularly long, cannot, as in the case of the vipers, be brought into a position perpendicular to the skull. In opistoglyphic species of the family, the so-called false snakes , the poisonous teeth are in the back of the upper jaw, while aglyphic or "real snakes" have no poisonous teeth.
nutrition
Adders have a rich range of prey that includes small mammals, birds, lizards, amphibians, fish, arthropods, and mollusks . Some adders are food specialists , like the African and Indian egg snakes , which feed exclusively on bird eggs.
Toxicity
Most snakes have neither hollow nor furrowed fangs. In some species, for example grass snakes, there is a very weak poison in the saliva that can paralyze small prey, but presumably primarily serves for pre-digestion.
The snakes are not a separate taxonomic group, rather they are a number of species within the snakes. They have furrowed poison teeth in the rear area of the upper jaw, through the outer furrow of which the poison is directed into the bite wound of a prey animal with chewing movements. For larger animals, however, false snakes are usually harmless, because on the one hand the position of the poisonous teeth prevents them from reaching their victim when they bite and, on the other hand, the venom of the false snakes is relatively weak compared to vipers and venomous snakes . In some species of snake , for example the boomslang (southern Africa) or the mangrove night tree snake (Southeast Asia), the bite can also be life-threatening for humans.
Poisonous snakes (Elapidae), despite their name, do not belong to the group of snakes, but form their own snake family.
Reproduction
Adders are with a few exceptions - such. B. the viviparous smooth snake native to Central Europe - egg-laying .
Systematics
The system of snakes is still the subject of current research. In 1999, based on morphological characteristics, Zaher classified the following twelve subfamilies as 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 several of these subfamilies are more closely related to the poisonous snakes (Elapidae), which is why the corresponding subfamilies Pseudoxyrhophiinae and Psammophiinae have been moved to a new family with the name Lamprophiidae . Of the original twelve subfamilies according to Zaher, the subfamilies Calamariinae , Colubrinae , Pseudoxenodontinae , Natricinae and the Dipsadinae remain in the family of the adder. The Xenodontinae and the Dipsadinae were distinguished by Cadle 1985 only on the basis of their area of distribution (South and Central America); the genetic studies show that the relationship of the genera in these subfamilies is not based on the area of distribution. Accordingly, the genera 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 therefore does not belong to the Boodontinae, but is the sister genus to the subfamily of the real snakes (Colubrinae). While Lawson et al. classify them in the Colubrinae due to uncertain data, Vidal et al. 2007 after a more detailed analysis a separate subfamily, the Grayiinae . The remaining genera of the subfamily Boodontinae are placed in the Lamprophiidae and Colubrinae.
Lawson et al. Also found that the family of vipers (Viperidae) are more closely related to the adder than the Pareatinae. prove. Further studies by Pyron et al. prove this and also show that the Pareatinae and the vipers are more closely related to the snakes than the subfamily Xenodermatinae, which Lawson placed next to the poisonous snakes. The Homalopsinae were described by Lawson et al. placed as sister family next to the vipers, Pyron et al. showed, however, on the basis of a broader database, that they stand next to the clade formed from Elapidae and Lamprophiidae. Accordingly, these three subfamilies were raised to family rank and are now called Xenodermatidae , Pareidae and Homalopsidae .
The subfamily Scaphiodontophiinae , which only consists of a genus that previously belonged to the real snakes (Colubrinae), was developed by Pyron et al. Introduced in 2010. Their molecular genetic studies showed that the Grayiinae are more closely related to the Colubrinae than the Scaphiodontophiinae, which also count as a subfamily.
External system
The adders are therefore one of seven families within the superfamily of the adder-like and viper-like (Colubroidae). According to Pyron et al. the following system arises within the Colubroidae:
| Adder-like and viper-like |
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The clade to which the snakes belong differs from the vipers by the lack of solenoglyphs , i.e. , retractable, poisonous teeth.
Internal system
The adder family itself is currently divided into seven subfamilies. The taxonomic position of the individual subfamilies to one another is less well established than that of the external system. According to Pyron et al. the following internal system results:
| Adders (Colubridae) |
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The snakes from the subfamily Colubrinae have an asymmetrical hemipenis with a single sulcus spermaticus . The calamariinae differ from the other snakes in their bone structure: the eye hole is only formed by the frontal bone and the parasphenoid , the parietal bone is not involved. The diagnostic feature of the Pseudoxenodontinae, which occurs only in Asia, is the very deeply forked hemipenis . Their sister taxons are the Dipsadinae, which live in America and typically have a forked spermatic sulcus. The water snakes (Natricinae) are characterized by a distinctive hemipenis, the sulcus spermaticus of which is strongly curved.
literature
- Wilfried Westheide , Reinhard Rieger: Special Zoology. Part 2: vertebrates and skulls. 1st edition. Spektrum Akademischer Verlag Heidelberg, Berlin 2004, ISBN 3-8274-0307-3 .
- Kurt Deckert, Gisela Deckert , GE Freytag, G. Peters, G. Sterba: Urania animal kingdom, fish, amphibians, reptiles. Urania-Verlag, 1991, ISBN 3-332-00376-3 .
Individual evidence
- ↑ Jürgen Martin: The 'Ulmer Wundarznei'. Introduction - Text - Glossary on a monument to German specialist prose from the 15th century. Königshausen & Neumann, Würzburg 1991 (= Würzburg medical-historical research. Volume 52), ISBN 3-88479-801-4 (also medical dissertation Würzburg 1990), p. 154.
- ↑ Colubridae in The Reptile Database
- ↑ The Reptile Database: Colubridae in Switzerland, Austria or Germany.
- ↑ a b c d e f R. Lawson, JB Slowinski, BI Crother, FT Burbrink: Phylogeny of the Colubroidea (Serpentes): New evidence from mitochondrial and nuclear genes . In: Molecular Phylogenetics and Evolution . tape 37 , 2005, pp. 581-601 ( online, PDF ). online, PDF ( Memento of the original from July 27, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b c d e f g h R. Alexander Pyron, Frank T. Burbrink, Guarino R. Colli, Adrian Nieto Montes de Oca, Laurie J. Vitt, Caitlin A. Kuczynski, John J. Wiens: The phylogeny of advanced snakes (Colubroidea), with discovery of a new subfamily and comparison of support methods for likelihood trees . In: Molecular Phylogenetics and Evolution . 2010, p. 329–342 , doi : 10.1016 / j.ympev.2010.11.006 .
- ↑ Nicolas Vidal, Anne-Sophie Delmas, Patrick David, Corinne Cruaud, Arnaud Couloux, S. Blair Hedges: The phylogeny and classification of caenophidian snakes inferred from seven nuclear protein-coding genes . In: Comptes Rendus Biologies . tape 330 , 2007, pp. 182-187 .
