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.