25 Q 2

Describe the different modes of respiration used by amphibians. What paradox do amphiumas and terrestrial plethodontids present regarding the association of lungs with life on land?

They use three different modes of respiration which are skin, mouth, and lungs. Skin provides an important supplementary avenue for gas exchange in anurans. When lung breathing carbon dioxide is lost primarily across the sikn while oxygen is absorbed primarily across the lungs.The rhythmical throat movements of mouth breathing occurs continuously before flank movements indicates that lungs are being emptied and refilled.

Although we usually associate lungs with terrestrial organisms and gills with aquatic ones, salamandar evolution has produced aquatic forms that breathe primarily with lungs and terrestrial forms that lack them completely. Amphiumas, a totally aquatic salamander group, lose their gills before adulthood and breathe primarily with lungs (secondarily through skin). Many species of terrestrial Plethodontis salamandars have no lungs, and use mainly cutaneous respiration (skin). It is made more efficient by having thinner skin over the capillaries, and is supplemented by sucking air in through the mouth and exchanging them across the bucal cavity.

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