DOMESTIC CAT
Cat hands grow narrow, curved claws.
Most of the time ligaments running over
the top of a cat's hands keep the claws
retracted inside sheaths. To catch prey, a
cat pushes off its hind legs and stretches
out its arms. Muscles along the top and
bottom of its hands contract, which
draws the claws out like switchblades.
The claws sink into the prey, the cat
shifts its weight to its hind legs, and the
hands draw the prey to the cat's mouth.
FROG
Frogs have evolved into thousands
of species with hands that have
changed to accommodate different
activities. Some of the species that
live in water grow webbed hands so
that they can swim. Tree frogs use
long fingers with expanded finger-
tips for climbing; they have even
evolved tiny adhesive disks on their
fingers that help them stick to
smooth surfaces such as leaves.