Animal adaptations refer to any type of development or unique behaviour that makes it easier for such an animal to live in its natural habitat. Adaptation is a very important evolutionary tool that weeds out the animals that cannot make the transition or change required to survive in a changing environment. Adaptation has made it possible for some animals or insects that may be terrestrial to also survive in aquatic environments. Two examples are the water spider and frog.
Legs and Feet
Frogs are amphibians, meaning that they are capable of surviving on the land and in the water. They spend most of their developmental stage exclusively inside the water. When they are still tadpoles, they have gills, just like fish. The gills enable them to breathe inside the water. Adult frogs have powerful hind limbs which they use to propel themselves into the air as they jump. They also have webbed feet, which enables them paddle while inside the water. Some tree-dwelling frogs have pads on their toes which enable them to grip surfaces as they climb.
Frogs have permeable skin, meaning that they are capable of absorbing oxygen and water directly through the surface of their skin. This adaptation may also work against the frogs because it can lead to excessive loss of moisture. Some frogs try to combat such a disadvantage by becoming nocturnal creatures. They remain in shadows and burrows during the daytime and only emerge at night when it is cool. Some frogs also have warts on their skin to help them blend into their environment more completely than they would if their skin was smooth.
Frogs have a large network of blood vessels located near the skin. This adaptation helps the frog to breathe when it is submerged in water. The oxygen passes directly from the water into the bloodstream of the frog, helping it to breather under water. Their nostrils also have valvelike apertures that open to let in air when they are on land. The valves shut to keep water out when they are under water.
Water spiders have two unique adaptations that help them survive on and inside water. They have a sticky substance on their legs that enables them to adhere to water plants. This adaptation helps prevent currents or moving water from sweeping them away. Water spiders also construct little airtight bubbles underneath the water for themselves. They transport air to the bubble by carrying air in a bell-shaped web located on their abdomen. They mostly breed inside the bubble and are able to avoid surface predators in their underwater bubbles.