Final answer:
Flightless birds, such as penguins, have evolved to live in aquatic environments. Flying reptiles, like plesiosaurs and ichthyosaurs, developed wings that allowed them to swim in the sea. The evolution of wings in insects and flight in birds are still not fully understood.
Step-by-step explanation:
Flightless birds, such as penguins, have evolved to live in aquatic environments. They have wings that are now adapted to swimming instead of flying. This evolution occurred when birds inhabited isolated islands with no land predators, making flight unnecessary.
Additionally, there are examples of reptiles evolving to become sea creatures, such as plesiosaurs and ichthyosaurs. These flying reptiles developed wings spanning up to seven meters, which were supported and extended by elongated fingers.
Although the evolution of wings in insects and the development of flight in birds are still mysteries, studying living vertebrates like bats provides insight into adaptations for flight.