Why would animals on opposite sides of the planet end up with nearly identical body parts? Unrelated species living in the same kind of place often face the same environmental pressures, and those pressures shape their physical traits in similar ways. To investigate this, you pick a biome — from desert to ocean to tundra — then choose two continents where that biome exists and find one species on each that fills a similar role. Comparing limb structure, teeth or beak shape, claw size, skin features, and even internal features like bone structure or stomach design reveals whether the shared traits match the demands of the biome.

When two unrelated species face the same environmental pressures in the same type of biome, the traits that help them survive and have more young can end up nearly identical. Pick a biome — desert, ocean, tundra — then find one species on each of two continents that fills a similar role. Comparing their limb structure, teeth or beak shape, claw size, skin features, and bone structure reveals convergent evolution: unrelated species developing similar features because the same environment rewarded the same traits.