In Other Species
Neoteny has been observed in all salamander families in which it seems to be a survival mechanism, in aquatic environments only of mountain and hill, with little food and, in particular, with little iodine. In this way, salamanders can reproduce and survive in the form of smaller larval stage, which is aquatic and vegetarian and requires a lower quality and quantity of food compared to the big adult, which is a terrestrial carnivore. If the salamander larvae ingest a sufficient amount of iodine, directly or indirectly through cannibalism, quickly begin the metamorphosis and transform into bigger terrestrial adults, with higher dietary requirements . In fact, in some high mountain lakes also live dwarf forms of salmonids caused by deficiency of food and of iodine in particular, which causes dwarfism with cretinism due to hypothyroidism, as it does in humans.
- The axolotl is a salamander that retains its juvenile aquatic form throughout adulthood and tiger salamander and Rough-skinned Newt can both retain gills into adulthood.
- Flightless birds' physical proportions resemble those of the chicks of flighted birds
- Adult bird morphology appears to be equivalent to the juvenile stage of the dinosaurs from which they evolved.
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