Table of Contents
Homologous and Analogous Structures
Homologous structures are structures in different species that have the same evolutionary origin. They are often similar in form and function. Analogous structures are structures in different species that have different evolutionary origins. They are often similar in function, but not in form.
Structures that are similar in their overall form and function, but not necessarily in their genetic makeup, are called homologous structures. For example, the arm of a human, the wing of a bat, and the flipper of a whale are all homologous structures, because they share a common ancestor and have similar overall forms and functions. Structures that are similar in their overall form but not in their function are called analogous structures. For example, the wing of a butterfly and the wing of a airplane are analogous structures, because they share a common overall form but have different functions.
Homologous Structures
Structures that have the same or similar function in different organisms are called homologous structures.
For example, the human arm and the wing of a bat are both homologous structures. They have the same basic function (they allow the organism to move), but they look different because they have evolved to serve different purposes in different organisms.
Analogous Structures
Analogous structures are structures that share a common ancestor and have similar features as a result of that common ancestor. For example, the wings of a bat and the wings of a bird are analogous structures because they share a common ancestor (the dinosaurs) and have similar features as a result of that common ancestor.
Analogous structures are structures in different species that have similar functions and appearances even though they are not related. An example of this is the wings of a bird and the wings of a bat. Both wings are used for flying, but they are not related. Another example is the flippers of a whale and the arms of a human. Both flippers and arms are used for moving around, but they are not related. Analogous structures are often used as evidence for evolution, because they show that different species can evolve to have similar features even though they are not related.
Difference between Homologous vs Analogous Structures
Homologous structures are those that have the same underlying structure, while analogous structures are those that have a similar function but are not structurally similar.
Structures that are similar in form but have different functions are called homologous structures. For example, the bones in your arm and the bones in a monkey’s arm are homologous structures. They look similar, but they have different functions.
Structures that are similar in form and function are called analogous structures. For example, the wings of a bat and the wings of a butterfly are analogous structures. They look similar, and they both have the same function.
Example of Homologous Structures
The human arm and the arm of a monkey are homologous structures. They have the same basic bones, muscles, and nerve endings. They are both arms because they have the same basic structure.
A common example of a homologous structure is the human arm. The arm is made up of bones, muscles, and ligaments that are all similar in structure and function. The arm is also used for locomotion, which is why the muscles in the arm are able to move the arm in different directions.
Example of Analogous Structures
The skeleton of a human and the skeleton of a cat are analogous structures. They are both vertebrates and have similar skeletal structures.
Pictorial Depiction of Homologous and Analogous Structures
The structures shown in the image below are all homologous structures. They are all derived from the same ancestor structure, and they all have the same basic function.
The structures shown in the image below are all analogous structures. They are not all derived from the same ancestor structure, and they do not have the same basic function. Instead, they are all adapted to serve different functions.
