The Science Behind Animal Symmetry

What percentage of animals exhibit bilateral symmetry?

• About 95%

• About 50%

• Less than 10%

• About 75%

Which type of symmetry do cnidarians like jellyfish exhibit?

• Fractal symmetry

• No symmetry

• Bilateral symmetry

• Radial symmetry

What unique growth pattern did the rangiomorphs exhibit?

• Linear growth

• Fractal growth

• Random growth

• Exponential growth

Which period is known for the earliest bilateral animals in the fossil record?

• Jurassic period

• Cambrian period

• Ediacaran period

• Cretaceous period

What advantage does bilateral symmetry provide in terms of movement?

• Circular movement

• No particular advantage

• Only backward movement

• Efficient and purposeful movement

During which evolutionary event did bilaterians become much more successful?

• Cambrian explosion

• Permian extinction

• Cretaceous-Paleogene extinction

• Carboniferous period

What is cephalization associated with in bilaterians?

• Development of radial symmetry

• Loss of symmetry

• Development of multiple limbs

• Development of a brain

Which animals have evolved to break their bilateral symmetry for specialized functions?

• Amphibians

• Cross-bill birds and some species of fish

• Most mammals

• Reptiles

What is the natural position of a flounder?

• No fixed position

• Inverted

• Upright

• On its side

Which group of animals are bilaterians but appear radial as adults?

• Mollusks

• Sponges

• Cnidarians

• Echinoderms