Amphibians and their role in the stable functioning of ecosystems

     The word Amphibians or Amphibia is used to name vertebrates, which existence (from their appearance to death, i.e. during their ontogenesis) is dual in nature. This means that each animal's life at the first stage, as a rule, begins with the larva stage and proceeds usually in sweet water bodies. Then later, during the second stage, a significant rebuilding or metamorphosis of the whole organism occurs and tadpoles turn into adult animals which spend the most part of their life already on land. Specific features of these animals reflect the main characteristic of their evolution - being related to fish through their origin they were the first among ground vertebrates which assimilated into ecosystems in the ground habitat. Usually, an ecosystem is understood as a community of jointly functioning organisms inseparably linked with each other and found in the state of continuous interaction both with each other and their physical environment.

      For the normal functioning of ecosystems it is very important to use the inorganic component of the environment and maintain trophic or feed circuits (= transportation of energy within the ecosystem). Amphibians play here an exceptionally important role since they, the only ones among all ground vertebrates, are characterized by the fact that one part of their life goes on in water (the larva stage) and the other - predominantly on land and in the air. At that, amphibious tadpoles feed on small aquatic invertebrates, microorganisms, aquatic plants, etc.The food ration of adult predator species consists of many groups of ground invertebrates and more rarely - vertebrates. In their turn, amphibians are the object of hunt for very many reptiles, birds and mammals.

      Amphibians are an exceptionally important link in transferring energy from energy accumulating sources like invertebrates to higher levels - reptiles, birds and mammals. Transportation of energy by amphibians is extremely effective since due to their cold-bloodedness they are able to exist at much lower temperatures as compared to other vertebrates. Comparison of warm-blooded and cold-blooded ground vertebrates shows that the former (birds and mammals) spend about 98% of energy received from food on heat generation and only 2% - on formation of new tissues. As opposed to this, the cold-blooded use the heat of the sun along with limited utilization of food energy for the heating of their body, which gives them the opportunity to use about 50% of its volume for the formation of new tissues.

      Moreover, though amphibians take longer to assimilate food they are more effective at transformation of its biomass. As compared to the warm-blooded with approximately the same size of the body, they reach reproductive maturity relatively later and have a longer life span. Some researchers believe because of their capacity to accumulate energy in ecosystems they even somewhat resemble plants. (Stebbins et al., 1995).