Quick Research Idea: Venn Diagram Compare and Contrast Compare and contrast whales, dolphins, and elephant seals. (Whales and dolphins have been living in the ocean longer than elephant seals and have had more time to adapt to the marine environment. Elephant seals are also very much at home in the water, because they have developed many adaptations that make it easy for them to live there. In fact they can dive as deep as any whale, and spend 90% of their time underwater. But unlike whales and dolphins, they still spend some of their time on land.)