Page 23 - One Million Things: Animal Life - The Incredible Visual Guide

Giant green anemone
Body can be
divided into two
equal halves
Five arms
Agrias claudina butterfly
radiate
from center

Red finger sponge
Ring of
tentacles around
central mouth

RADIAL SYMMETRY
Sea anemones and their relatives show radial
symmetry. Their body parts are arranged, like a bicycle
wheel, around a central point. Any line drawn through
the center divides the animal into two equal halves. Scarlet
Sponge grows Starfish have a special type of radial symmetry, with body starfish
fixed to a reef, rock, parts arranged around the center in five equal sections.
or the seabed

Fiddler crab

Male crab has one
claw much larger
than the other

LARGE CLAW
Male fiddler crabs look lopsided because one of their claws is
much bigger than the other. They raise this claw into the air and
wave it around to attract females during courtship. Males also fight
claw-to-claw to defend their mudflat burrows against other crabs.

Flounder

SPIRAL SHELL Spiral shell encloses
Most snails are not really symmetrical. They twisted body
have spiral shells that protects their bodies and
internal organs. The shell is a portable retreat into
which the snail can withdraw if danger threatens. Snail

CHANGING SIDES
Adult flatfish, such as this flounder, have an unusual
symmetry. When it hatches, the flounder is bilaterally symmetrical,
but shortly afterward a dramatic change takes place. The eye on the
fish’s left side migrates to rest next to the right eye. The fish moves to the
seabed, where it will now live, and rests on its left side, now its underside.
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