Breathing amphibians

info fauna
Coordination office for amphibian and reptile protection in Switzerland (karch)

Systematics

Amphibians are a class of vertebrates. The amphibians include the tailed amphibians (newts and salamanders), frogs (disc bugs, tree frogs, frogs and toads), as well as the caecilians (amphibians without limbs that only occur in the tropics). A total of 7,000 species of amphibians are known today. In Switzerland, however, the biodiversity is much lower with just 19 species.

 

 

features

Skeleton:

  • All native amphibians, when fully developed, have four limbs. Tail amphibians keep their tail even after metamorphosis; Frogs are tailless.

Skin:

  • Amphibians have flaky, glandular skin. The glands are used to produce various secretions, including skin toxins that inhibit the growth of bacteria and fungi on damp skin, and bitter substances to ward off predators.
  • Not only can amphibians breathe through their lungs, but their thin skin also allows them to take in oxygen through the skin. A third variant of oxygen uptake takes place via the oral mucous membranes, which is why one can often observe a rapid up and down movement of the throat, especially in frogs.
  • Amphibians don't drink. The fluid is also absorbed through the skin.

The glandular and thin skin of the amphibians serves to ward off diseases and enables them to breathe and absorb water. Pictured: skin of the common toad.

 

Thermoregulation:

  • All amphibians are cold-blooded, i.e. they do not generate body heat, but their body temperature fluctuates with the outside temperature. However, they can influence their body temperature by moving to a warmer or cooler environment.

 

Way of life

The vast majority of amphibians have a two-phase life cycle: aquatic larvae hatch from the eggs and breathe through their gills. In the frogs, the gills are covered by a gill cover within a few days and are then no longer visible, while in the tail amphibians the gill tufts remain visible. During larval development, called metamorphosis, the front and rear legs grow. At the end of the metamorphosis there is a switch to lung breathing; the gills are regressed in frog and tailed amphibians. In the case of the frogs, the diet is also switched from mostly plant-based food to insect food and the tail is absorbed as an energy reserve during this fasting period. The larvae of the tailed amphibians already eat zooplankton and small insects and there is no change in diet.

While the larval stages are almost always aquatic, the binding of the fully developed amphibians to the water depends heavily on the species. Species such as common toad and common frog are only found to mate by the water, while green frogs spend the whole year around the pond.

Amphibians spend the winter in places protected from frost.

 

Fig. 1: Life cycle of a water frog (left) and a newt (right). Pictures: Ursina Tobler