* Reduced drag: A streamlined shape minimizes resistance from the water as the bird dives, allowing for greater speed and efficiency. This is crucial for catching fish, which are often fast and elusive.
* Increased maneuverability: A streamlined body allows for easier turning and maneuvering underwater, enabling the bird to chase and capture fish in a variety of locations.
* Reduced impact: The streamlined shape helps distribute the force of impact when entering the water, minimizing the risk of injury to the bird.
* Improved hydrodynamics: The shape of the bird's body and wings acts like a foil, creating lift and propelling the bird through the water. This allows for longer dives and the ability to stay submerged for extended periods.
Examples:
* Loons: These birds have a torpedo-shaped body and long, pointed beaks, perfectly suited for diving and catching fish.
* Gulls: While they aren't primarily divers, gulls often dive for fish, and their streamlined bodies help them penetrate the water surface.
* Penguins: These flightless birds have adapted to an aquatic lifestyle, and their streamlined bodies allow them to swim and dive with incredible speed and efficiency.
Evolution:
Birds have evolved this streamlined shape through natural selection. Those individuals who were better suited to diving and catching fish, thanks to their streamlined bodies, were more successful at finding food and passing on their genes. Over time, this led to the evolution of the streamlined shape as a common trait among diving birds.