Ch. 1 Sec. 2

Symmetry

Radial Symmetry

•1 line of symmetry•halves that are mirror images•front end w/ sense organs•quick movement

Bilateral Symmetry

•many lines of symmetry•no distinct front end •live in water•move slowly

• balanced arrangement of parts

Types of symmetry Types of symmetry

asymmetry• NO symmetry

sponges

radial symmetry• many lines of symmetry that all go thru. central point

animals with radial symmetry

sea urchin

sea starbrittle star

sand dollar

SEA ANEMONE

Clownfish hide in the poisonous tentacles of the sea anemone.

bilateral symmetry• 1 line that divides it into halves that are mirror images

A shape has bilateral symmetry when one halfA shape has bilateral symmetry when one half

of it is the mirror image of the other halfof it is the mirror image of the other half..

Animals that have bilateral symmetry

Symmetry of the Human FaceSymmetry of the Human Face

• No face has perfect mathematical symmetry!

• But plastic surgeons study facial symmetry to help them reconstruct faces.

• It is thought that as a face gets closer to symmetrical more people think it is beautiful.

Is the Face Really Symmetrical?

Notice that the photos of each child's face is made up of the original photo, 2 left sides and 2 right sides.

right / right left / left original photo

right/rightright/right left/left left/left original photo original photo

right/ rightright/ right left/left left/left original photo original photo

right/ right left/left original photoright/ right left/left original photo

The Symmetry of Capital Letters

• some have one line of symmetry

• some have two lines of symmetry

• some have no lines of symmetry              

                                     

Bilateral Symmetry demonstrations

Types of Animals

radial symmetry

radial symmetry• many lines of symmetry that all go thru. central point

bilateral symmetry

no symmetry (asymmetry)

radial symmetry

•all live in water

radial symmetry

•do not have distinct front or back ends

radial symmetry

•most do not move fast

radial symmetry

bilateral symmetry

•1 line that divides it into halves that are mirror images

bilateral symmetry

•distinct front ends (sense organs)

Mark the line of symmetry

Activity- Magazine pics