Chapter 28, Problem 26A

Summary Introduction

To write: The modified structure and physiology of amphibians, presently adapted to temperate and tropical climates enable themto live in colder climates.

Introduction: Modern amphibians such as salamanders, toads, and frogs. Most amphibians have four legs, moist skin without scales, and exchange of gas through the skin, double loop circulatory system, lungs and marine larvae.

Explanation of Solution

Most amphibians, as larvae, exchange gases through their skin and gills. As adults, the majority breathe via the lungs, their thin, moist skin and mouth cavity lining. Frogs can breathe in or out of water via their skin. This capability allows them to spend the winter in the mud at the bottom of a pond, protected from the cold. Ectotherms cannot control their body temperatures through their metabolism, so they need to be able to sense where they can move to get warm or cool down.