This means that their body can be divided into two equal halves that are mirror images of each other along a central axis.

Here's why this is important for vertebrates:

* Movement: Bilateral symmetry allows for efficient and directed movement. Animals can move forward in a straight line, and limbs on either side of the body work in coordination.

* Senses: Most vertebrates have specialized sense organs (like eyes and ears) located on either side of the body, allowing them to perceive their surroundings from multiple angles.

* Cephalization: Bilateral symmetry leads to the development of a head region (cephalization) containing the brain and sensory organs. This allows for a more advanced nervous system and better response to the environment.

While many vertebrates display this symmetry, there are some exceptions. For example, some flatfish have their eyes on one side of their body due to a developmental shift.