Bilateral symmetry

Definition

Bilateral symmetry is a body plan in which the left and right sides of an organism are mirror images of each other. This type of symmetry is common in animals with a head and tail region, promoting efficient movement and sensory processing.

5 Must Know Facts For Your Next Test

1. Bilateral symmetry is found in most animals, including humans, arthropods, and vertebrates.
2. It typically allows for streamlined movement and the development of directional senses such as sight and smell.
3. Animals with bilateral symmetry often have a centralized nervous system or brain located at the anterior end.
4. This type of symmetry is associated with cephalization, where sensory organs and nerve cells are concentrated at the front end of the organism.
5. Bilateral symmetry enables more complex behaviors and interactions with the environment compared to radial symmetry.

Review Questions

• What are some examples of animals that exhibit bilateral symmetry?
• How does bilateral symmetry benefit an organism's movement and sensory processing?
• Explain the relationship between bilateral symmetry and cephalization.

Related terms

Radial Symmetry:

A body plan where parts are arranged around a central axis, as seen in starfish and jellyfish.

Cephalization:

The concentration of sensory organs and nerve cells at the front end of an organism.

Anterior-Posterior Axis: A directional term referring to the front (head) to back (tail) orientation in bilaterally symmetrical organisms.