Animal Kingdom — BIOLOGY STD 11 Science — Question

Amphibians are adapted to survive in both aquatic as well as terrestrial life. As research has proved that the life started in water and finally moved to land and air. Aquatic life has its own limitations. The area is limited and there is less variety in primary producers which limits the type of food available to the animals living in water. Specially in deep sea limited reach of sunlight doesn't permit variations of certain kind. Following paragraphs highlights certain features which amphibians developed to adapt in a terrestrial environment.

• Emergence of lungs enabled frogs to breathe in air. When they are in water they breathe through skin. Some aquatic mammals, like whale need to come on surface, frequently, to breathe in oxygen which limits the time they can chase a prey underwater. So frogs are having a better mechanism to do so.
• Emergence of four limbs meant frogs can travel larger distances. Their webbed fingers enable them to swim, while the stronger hind legs are used for better jump. Ease of mobility is helpful from two perspectives. One is in getting food and another is in saving from predators.
• Frogs are ammonotelic which is more suitable for aquatic life. But later animals have switched over to ureotelic and urecotelic mode of excretion.
• The feeding habit of frogs enables them to survive both on land as well as on water. While on land they eat small insects.
• Presence of nictitating membrane over eyes allows them to swim under water. In higher animals, like mammals nictitating membrane becomes a vestigial organ showing their relationship with the aquatic life.