Rough-skinned newt
Taricha granulosa
The Rauhäutige Yellow-bellied newt ( Taricha granulosa ), and Western American Rauhaut pig (based on the English name of Rough -skinned newt ), belongs to the family of the Real salamander. A special feature of this pig is a protective mechanism against the natural enemies through the formation of a strong poison, the Tetrodotoxins ( TTX).
Features
The Rauhäutige Yellow-bellied pig is 12 to 22 inches long. The warty skin is colored upper side light brown to black and the belly yellow to orange. In the mating season the males have an enlarged Schwanzsaum, dark calloused toes and a more curved sewer.
Occurrence
The Rauhäutige Yellow-bellied pig can be found on the North American Pacific coast from southern Alaska to California. He lives in ponds, lakes and slow -flowing streams in up to 2700 meters above sea level.
Reproduction
The mating season lasts from December to July. In the water, the male clasps the female from above with legs. On a gelatinous cone semen is deposited on the bottom and recorded with the cloaca of the female. The spawn is fixed on the leaves of aquatic plants.
Toxicity and Evolution
The protection by the formation of tetrodotoxin ( TTX) is widespread in the animal kingdom. For example, you will find this protective mechanism, inter alia, in pufferfish and blue Ringed Octopus. Through the production of this poison is one of the genus Taricha the most toxic newts. TTX is also called Tarichatoxin; the genus was eponymous. The Yellow-bellied newt Rauhäutige is probably the most poisonous species of the genus. When TTX is a neurotoxin that is produced in the glands of the skin and a defensive substance against predators is. The Common Garter Snake ( Thamnophis sirtalis ) is the only potential enemy who has developed through evolutionary adaptation, resistance to that poison. After eating the pig the snake for a few hours in a resting stage has to move so that their immune system can work efficiently. The pig in turn shows in regions where this snake occurs, a greatly increased production of the poison. One can speak of an evolutionary arms race ( coevolution ). Since the production rate of the pig poison, and the resistance of snakes in different populations and regions, depending on the degree of concentration vary, it is called in the Anglo-Saxon literature by " geographic mosaic theory of evolution ".
Died 1979 in Oregon, a 29- year-old man after he had a 20 cm long Rauhäutigen yellow belly pig swallowed a dare. It is the only known case of death of a man by the pig.
The poison Education
How exactly tetrodotoxin is formed in the skin of the pig is still unclear. In some bacteria (eg in species of Vibrio and Pseudomonas ) the production of the toxin was detected. Thus, a presumption assumes that such bacteria as endosymbionts live in the skin of the pig and produce this poison. This hypothesis, however, was called into question: A search for known tetrodotoxin ausscheidenen bacteria within the tissues of the yellow-bellied pig Rauhäutiger the 16S rRNA analysis was used with no rRNA of these bacteria in the skin tissue, liver or Eigewebe was found. Minor traces of the rRNA of TTX -producing bacteria were found in the intestine, but the small amount of RNA, which is the number of these bacteria do not seem to meet the large amounts of the toxin produced. Also the transport of TTX to the skin tissue should be detectable, which is not the case. Another study also argues against the inclusion of the poison -forming bacteria through the food. So the pig was kept in captivity for a year and in that time there was no decrease in the toxic content but even an increase. If the poison -forming organisms were added by the food itself would have the poison content, or must reduce the formation, since at this time was not a natural food of the pig are available.
These results suggest that the pig has its own genes for the formation of the poison and does not require the aid of bacteria. This would mean that the ability of TTX to produce in bacteria and the newt species is developed independently from each over the course of evolution. Another publication, the formation of TTX in puffer fish by Vibrio in question. A definitive solution to these problems would be the analysis of the genes responsible for the production of poison. The possibility of self- formation of TTX with or without acting as endosymbiont bacteria therefore remains under discussion.