Convergent adaptation refers to different species of organisms with quite distant kinship. Because they live in the same or similar environment for a long time and accept the same ecological environment choice, only the types that can adapt to the environment can be preserved. Differential adaptation refers to the appearance of the same species of organisms in order to adapt to the environment if they live under different conditions for a long time, There are obvious differences in habits and physiological characteristics.
According to the above definition, which of the followings belongs to convergent adaptation
Mammalian whales, dolphins, walruses, seals, fish and sharks are far apart in kinship, but they all live in the ocean for a long time, and the whole body becomes a spindle suitable for swimming