Final answer:
Frogs have a dark dorsal side and light ventral side, an adaptation known as countershading, to camouflage from predators. This, along with their specialized eyelids and tympanum, are critical adaptations for survival in their environments.
Step-by-step explanation:
The dark dorsal side and the light ventral side of a frog is an adaptation known as countershading, which helps provide camouflage from predators. When predators look down on the frog from above, the dark dorsal side blends with the darker environments underwater or on the forest floor. Conversely, when predators or prey look up at the frog against the light sky or water surface, the light ventral side makes it more difficult to see. This adaptive trait is complemented by the frog's skin texture and coloration that aid in blending with their environment.
In addition to their skin adaptations, frogs have three eyelid membranes that protect their eyes and aid their vision in different environments, both on land and underwater. Their tympanum, a part of their hearing apparatus, is well-developed to pick up on sounds, which plays a role in communication and predator avoidance. Frogs are also known to change from having a tail during their tadpole stage to losing it as adults, which is an adaptation to their life stages from water to land.