Convergent evolution
Seals and penguins both have streamlined body forms that allow them to move through water efficiently. This similarity in body shape is mostly likely the result of: convergent evolution .
Convergent evolution is the mechanism in which organisms of different species or lineage independently evolve similar traits such as adaptations, body shape, colors and organs. Convergent evolution produces corresponding structures that functions the same way but were not possessed by the last common ancestor of those species.