Bilateral symmetry
Bilateral Symmetry
Bilateral symmetry (pronounced: bi-lat-er-al sym-me-try) is a fundamental property of many organisms in the animal kingdom. The term originates from the Latin bilaterus, meaning "two sides", and the Greek symmetria, meaning "measure together".
Definition
Bilateral symmetry refers to the characteristic of organisms where they can be divided into identical halves along a central axis, typically a vertical plane. This means that the left and right sides of the organism are mirror images of each other.
Examples
Examples of organisms exhibiting bilateral symmetry include most vertebrates, such as mammals, birds, reptiles, and fish, as well as many invertebrates, like insects, spiders, and even some types of mollusks.
Contrast with Other Forms of Symmetry
Bilateral symmetry is contrasted with radial symmetry, where an organism can be divided into identical parts along any vertical plane through the central axis, and asymmetry, where no plane can divide the organism into identical halves.
Evolutionary Significance
The evolution of bilateral symmetry is believed to be a major factor in the development of complex life forms. It allows for a streamlined body plan, efficient locomotion, and the development of a centralized nervous system, including a brain, which is typically located at the anterior (front) end of the organism.
Related Terms
- Anterior: The front end of an organism in bilateral symmetry.
- Posterior: The back end of an organism in bilateral symmetry.
- Dorsal: The top side of an organism in bilateral symmetry.
- Ventral: The bottom side of an organism in bilateral symmetry.
External links
- Medical encyclopedia article on Bilateral symmetry
- Wikipedia's article - Bilateral symmetry
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