Page 38 - 10-BIO-15-newflip

16. Support and Movement eLearn.Punjab

In the anurans, the entire skeleton and muscular system has become specialized for the peculiar
swimming and jumping methods of locomotion; by means of extensor thrusts of both kind of
limbs, acting together.

Frogs and toads also walk and hop on land due to its strong hind limbs.

Locomotion In Reptiles

The life style of reptiles reveals striking adaptations for locomotion. They move better than
amphibians due to the evolution of skeleton. The reptiles use method of walking and running.
The general form of the reptilian skeleton is based on one inherited from ancient amphibians. The
skeleton is highly ossified to provide greater support.

Reptiles have cervical vertebrae. The first two cervical vertebrae (atlas and axis) provide greater
freedom of movement for head. The axis is modified for rotational movement. The ribs of reptiles
may be highly modified. The ribs of snakes have muscular connections to large belly scales to aid
locomotion. Many prehistoric reptiles were bipedal meaning that they walked on hind limbs. They
had a narrow pelvis and heavy out stretched tail for balance. Bipedal locomotion freed the front
appendages, which became adapted for prey capture or flight in some animals.

Locomotion in Air

The skeleton of a bird is modified for flight. The most obvious adaptations are the bones with large
air spaces which make them lighter.

The fore limbs evolved into wings with very strong pectoral muscles which pull the wings up and
down. The sternum is modified to form keel. The keel is needed for the attachment of muscles.

The body is covered with feathers which give the wing a large surface area to keep the birds in air.
They also keep their bodies warm, so that they can produce enough energy to fly.

The body is streamlined to cut clearly through the air. The feathers lie smoothly against its body, so
that the air can easily flow over them. A bird can fly either passively by gliding or actively by flapping
its wings.

38