Reproduction
Mating occurs on land, the male clasping the female at the arms, and the impregnation is internal. S. atra is an ovoviviparous amphibian, giving birth to two live young, or rarely three or four. They may measure as much as 50 mm. at birth, the mother measuring only 120. The uterine eggs are large and numerous, but as a rule only one fully develops in each uterus, the embryo being nourished on the yolk of the other eggs, which more or less dissolve to form a large mass of nutrient matter. The embryo passes through three stages:
- still enclosed within the egg and living on its own yolk
- free, within the vitelline mass, which is directly swallowed by the mouth
- there is no more vitelline mass, but the embryo is possessed of long external gills, which serve for an exchange of nutritive fluid through the maternal uterus, these gills functioning in the same way as the chorionic villi of the mammalian egg.
Generally, at altitudes of 650-1,000 metres, a pregnancy lasts 2 years, and at altitudes of 1,400 to 1,700 metres, the pregnancy lasts 3 years.
Read more about this topic: Alpine Salamander
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