Japanese fire-bellied newt
|Japanese fire-bellied newt|
Japanese fire-bellied newt
|( Boie , 1826)|
It is a water newt that can be up to 12 centimeters long (in captivity supposedly also 15 centimeters). Bulges in the ear glands are clearly visible on the compact head ; these contain a poisonous skin secretion to ward off predators. The skin of the trunk appears grained. The upper side is colored dark brown to matt black; on the upper flanks you can sometimes see small orange-red spots. The ventral side is colored orange to deep red. In addition, there are often large black and sometimes white spots, which in some cases can also be missing. The pattern of spots on the abdomen makes the animals individually distinguishable (compare: Northern crested newt ). The tail is compressed laterally. During the stay in the water, the tail edges widen. The male also forms a thread at the end of the tail; the female lacks this. The male's cloaca is also more bulging at the mating season. In the water costume, male specimens also have purple hues on the flanks and tail, mostly blue with red spots.
Forms and subspecies
Cynops pyrrhogaster is a variable species, which produces several forms in its area of distribution, which differ morphologically, genetically and in terms of their reproductive behavior in some cases considerably. Well-known forms are, for example, the "Sasayamae form" (West Honshu), the "Kanto form" (Kanto plain around Tokyo) and the "Tohoku form" (North Honshu). So far only the Sasayamae form has been described as a separate subspecies: Cynops pyrrhogaster sasayamae (Mertens 1969). It shows a characteristic reproductive behavior in which the male places a hind foot on the female's back during courtship and later also on the neck. The " kanto form" of Cynops pyrrhogaster is possibly a species of its own.
The species occurs on all major islands of Japan with the exception of Hokkaidō and is known there as Akahara imori ( Japanese 赤 腹 井 守 ). In addition, some smaller, offshore islands are settled. The very similar swordtail newt ( Cynops ensicauda ) with two subspecies is known from the Ryūkyū Islands , but it does not occur on the main islands.
Stagnant bodies of water such as weed ponds, irrigation ditches and rice fields are preferred as habitats , which the newts inhabit largely in an aquatic manner. Outside of the breeding season in spring and early summer as well as in the youth phase, the animals also move to rural life and then hide under stones and dead wood.
Reproduction, individual development
The mating behavior in the water is very similar to that of the European newts (compare for example: pond newts ). Then the female lays the eggs one by one on aquatic plants and folds them into leaves with the help of the hind legs. The larvae hatch after about a week of embryonic development and initially feed on their yolk supply . When they go into the swimming phase, you can see three large tufts on the back of the head, which are used for gill breathing . After a few weeks the larva gets forelegs. It already feeds on water fleas and mosquito larvae. Some time later, the rear pair of legs also becomes visible. Shortly before the metamorphosis , the skin pigments increase and speckles appear. The breathing is switched from the gills to the lungs and skin , so that the young animals can now go ashore. At two to three years of age they themselves become sexually mature; until then they live terrestrially .
The high regenerative capacity of body parts of the Japanese fire-bellied newt has been investigated in a long-term experiment. It turned out that repeatedly removed eye lenses grew back completely up to 18 times.
- Michael & Ursula Franzen: fire bellied newts . Herpeton Verlag, 2005. ISBN 3-936180-15-6
- Heinrich Boie: Characteristics of some Japanese amphibians . In: Isis von Oken . tape 19 , 1826, pp. 203-216 ( biodiversitylibrary.org ).
- Franzen & Franzen (see "Literature"): pp. 54ff.
- Terutake Hayashi & Masafumi Matsui: Biochemical differentiation in Japanese newts, genus Cynops (Salamandridae). Zoological Science, 5, pp. 1121-1136, 1988, pp. 1134.
- Franzen & Franzen (see "Literature"): p. 61.
- Goro Eguchi, Yukiko Eguchi, Kenta Nakamura, Manisha C. Yadav, José Luis Millán & Panagiotis A. Tsonis: Regenerative capacity in newts is not altered by repeated regeneration and aging. Nature Communications 2, article number: 384, doi : 10.1038 / ncomms1389 , July 12, 2011.