Homologous structures are structures in different species that share a common ancestry. These structures may have different functions but are similar in form and structure.
In the case of the images above, the human arm, cat forelimb, whale flipper, and bat wing are homologous structures. While they may have different functions in each animal (for example, grasping in humans, running and climbing in cats, swimming in whales, and flying in bats), they all share a similar bone structure with the same bones (humerus, radius, ulna, carpals, metacarpals, and phalanges) arranged in a similar pattern. This similarity indicates that these structures evolved from a common ancestor.
Analogous structures, on the other hand, are structures in different species that have similar functions but do not share a common ancestry. Wings from a cardinal and wings from a fly are analogous structures because they have similar functions (both allow the organisms to fly) but are not derived from a common ancestor. In this case, wings have evolved independently in birds and insects to serve a similar purpose, but they are not homologous structures.
Define homologous structures in your own words.
How does each of these homologous structures function in each animal?
Explain why the images shown above from humans, cats, whales, and bats represent homologous structures. Be specific!
Define analogous structures. Explain why wings from a cardinal and wings from a fly are analogous structures.
1 answer