Station 9 -
Amphibians absorb water and oxygen through their skin and many species undergo their larval stages in aquatic environments. These characteristics make them very sensitive to disturbance in their environments; therefore scientists consider them to be good bio-indicators of change. There is international concern about these animals, since during the last three decades scientists have detected a worldwide decline in amphibian populations, with many species going extinct.
Detecting and identifying the presence of amphibian species is of great importance to evaluate habitat conditions. We have found in our research area four species of salamanders which are in two families:
Western red-backed (Plethodon vehiculum)
and Ensatina (Ensatina eschscholtzii)
The common name for this family describes its bizarre trademark: no lungs! An astounding feature for a vertebrate, when you think about it. How do they manage to breathe? Plethodontids respire through their thin skins and the tissue in their mouths. Dry tissue cannot perform gas exchange, so this salamanders’ skin has to remain moist all the time, for this reason they are confined to damp places - beneath logs and rocks, burrows, crevices, etc and they emerge only at night or during high humidity conditions.
Another interesting characteristic of this family is the presence of a specialized structured called the “nasolabial groove”. This furrow that runs between the nostril and the lip works as a chemical receptor and plays an important role in social interactions.
The absence of lungs, rather than a disadvantage for survival, seems to be one of the features which contribute to the success of this family of amphibians: there are more than 350 species in the world, accounting for more than half of the described species of salamanders.
Long-toed (Ambystoma macrodactylum)
and Northwestern salamander (A. gracile)
Existing only in the New World, this family of salamanders has a rather secretive life-style, dwelling most of their time inside rotten logs and subterranean moist places (hence their common name). During the onset of the spring rains, adults venture overland in nocturnal migrations, gathering to mate in seasonal or permanent ponds.