A penguin is a bird. Penguins belong to the avian family Spheniscidae, and they are a group of flightless aquatic birds. While they share some similarities with ducks in their aquatic lifestyle and swimming abilities, they are distinct from ducks taxonomically. Penguins have evolved unique adaptations to thrive in cold, aquatic environments and are well-suited for life at sea. They have streamlined bodies, and flipper-like wings that act as powerful flippers for swimming and are exceptional divers. Penguins also have a specialized layer of feathers that provide insulation and waterproofing, allowing them to stay warm and dry in icy waters.