Animal classification is based on characteristics like the presence of a vertebral column or backbone and the type of body symmetry. Most animals have bilateral symmetry, meaning their bodies can be divided into matching left and right halves. A small percentage have radial symmetry arranged like a wheel or are asymmetrical with no clear pattern. Body symmetry allows for streamlining and the formation of a central nervous system.

2. Introduction
Animal classification When classifying animals
we look at some major characteristics.
Vertebrae- this is a bone structure that supports
and protects the spinal chord of animals.
The spinal chord connects the brain to every
nerve in the body.
Invertebrates- are animals without a backbone.
97% of all animal species are invertebrates.
These animals have other protective structures,
like shells and exoskeletons.

3. Symmetry
Arrangement of body parts around a central axis
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Types of Body Symmetry
Asymmetrical - animals have no particular
symmetry.
Radial symmetry - means the animal is
organized similar to a wheel. Any longitudinal
cut will give off in an equal half.
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Bilateral symmetry - means the animal has
definite right and left halves.

5. Most animals are bilaterally symmetric, including
humans.
It could be divided into matching halves by drawing a
line down the center.
It permits streamlining, favors the formation of a
central nerve center, contributes to cephalization, and
promotes actively moving organisms.

6. Radial Symmetry
Radially symmetric animals are symmetrical
about an axis extending from the center of
the oral surface.

7. Asymmetrical
Do not show definite symmetry.

8. •
Biradial symmetry
In addition to the anteroposterior axis,
there are also two other axes or planes
of symmetry at right angles to it and to
each other.