What is a common adaptation for mammals living in an aquatic environment?

A streamlined body is a common adaptation for mammals living in an aquatic environment because it minimizes water resistance and allows for efficient movement through water. Aquatic mammals, such as dolphins and seals, have evolved to have a shape that reduces drag, enabling them to swim faster and conserve energy while foraging for food or escaping predators. This adaptation is crucial for their survival, as it enhances their ability to navigate and thrive in their watery habitat.

In contrast, adaptations like thick fur would be more suited for terrestrial mammals that require insulation to stay warm, while long legs are typically found in land animals that run or walk efficiently on solid ground. High endurance, while beneficial, does not specifically address the unique demands faced by aquatic mammals, which primarily rely on their streamlined body shape to overcome the challenges of living in water.