**Adaptations for swimming in animals**

**Introduction:**
Swimming is a specialized mode of locomotion that requires specific adaptations in animals. While many animals are capable of swimming to some extent, some are better adapted for it than others. Among the given options, the penguin is the most adapted for swimming.

**Adaptations of a Penguin:**
Penguins are flightless birds that have evolved numerous adaptations to excel in their aquatic environment:

1. **Streamlined Body Shape:** Penguins have a streamlined body shape that reduces drag in the water, allowing them to move efficiently through the water.

2. **Flipper-like Wings:** Penguins have modified wings that have evolved into flipper-like structures. These flippers are adapted for propulsion and steering in the water, enabling penguins to swim with great agility.

3. **Webbed Feet:** Penguins have webbed feet that help them to paddle through the water. The webbing increases surface area, providing more thrust and stability during swimming.

4. **Dense Feathers:** Penguins have dense and waterproof feathers that provide insulation and buoyancy. These feathers trap air, reducing heat loss and helping the penguins float on the water's surface.

5. **Counter-shading:** Penguins have a unique coloration known as counter-shading. Their dark-colored back camouflages them from predators above, while their white belly blends with the light from above, concealing them from predators below.

6. **Efficient Respiratory System:** Penguins have a highly efficient respiratory system that allows them to extract oxygen from the air and store it for extended periods while underwater. This adaptation enables them to stay submerged for long periods during their hunting dives.

7. **Strong Muscles:** Penguins have powerful muscles that provide the necessary strength for swimming and diving. These muscles enable them to propel themselves through the water and catch their prey.

**Conclusion:**
Out of the given options, the penguin is the animal best adapted for swimming. Its streamlined body, flipper-like wings, webbed feet, dense feathers, counter-shading coloration, efficient respiratory system, and strong muscles make it highly suited for a life in the water. Penguins are expert swimmers, capable of diving to great depths and maneuvering with impressive agility.