Sharks and whales both have streamlined bodies and tail flukes. How do we know that these similarities are because of convergent evolution?

Sharks and whales exhibit similar streamlined bodies and tail flukes due to convergent evolution, a phenomenon where unrelated species evolve similar traits in response to comparable environmental pressures. Despite these similarities, sharks are fish and whales are mammals, indicating that their common ancestry is distant. Genetic and anatomical studies reveal significant differences in their structures and developmental pathways, supporting the idea that these features evolved independently. This adaptation enhances their efficiency in swimming, showcasing how different lineages can arrive at similar solutions for survival in aquatic environments.