Vocabulary list
bilateral
symmetry - the fact of the two halves of something on either side of a
particular line being exactly the same / radial
symmetry - the condition of having similar parts regularly
arranged around a central axis
cephalization - nervous
tissue becomes concentrated toward one end of an organism
body
cavity - any
fluid-filled space in a multicellular organism other than those of vessels
Symmetry
With the exception of sponges, every kind of animal
exhibits some type of body symmetry. Some animals exhibit radial symmetry, in
which any number of imaginary planes can be drawing through the center, each
dividing the body into equal halves.
More complex animals have bilateral symmetry, in which
only a single imaginary plane can divide the body into two equal halves.
Animals with bilateral symmetry usually exhibit cephalization, which is the concentration
of sense organs and nerve cells at the front of the body. Most animals have a
body cavity, which is a fluid-filled space that lies between the digestive
tract and the body wall.
Answer the questions:
Can you name asymmetrical animals?
What animal is an example of radial symmetry?
What symmetry do people have?
What is cephalization?
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