How does Terrestrial Adaptation occur in Animals ?

Adaptation in Animals to Rapid Movement:

All fast- moving animals have streamlined bodies this is for reducing the resistance to the environment (air, Water, land) as much as possible. Horse, antelope and other terrestrial fast runners have head, neck and body joined by smooth, even curves, so that the whole body narrows towards the head and tail. Birds fly smoothly in air as they have light, streamlined body covered with feathers, forelimbs modified into wings, compact bones provided with air cavities and lungs connected with air-sacs.

Protective Adaptation in Animals:

The shells of tortoises and of the land snails are the example of protective adaptation in the animals. Besides prote4ctive body covering animals can also change their body color so as to match with the background and thereby escape the notice of the enemy. This may also be regarded as a protective device.

Offending the Enemy

Many animals like scorpions, wasps, bees have poison gland and stings. Some snakes are highly poisonous. Some animals discharge substances which evaporate to produce offensive odour. They may also discharge irritable fluids for their protection. A fish (electric ray) can generate electric current to give shock to its pursuer.

Deluding the Enemy when attacked by its enemy, some lizards shed their tails. This distracts the attacker and the lizard escapes. The defensive mechanism of breaking off its tail is known as autonomy. Some marine mollusks like Sepia release a dark black, ink-like chemical in water, when pursued by its enemy. This obscures the vision of enemy and the Sepia escapes.

Coloration and Climbing Adaption

The chameleon (Chameleon calcaratus), a reptile similar to lizard, is know for changing its colour to resemble that of its surroundings. It is found in different parts of India and is known as patchoudi in Tamil, ooservalli in Telugu and chhipkili in Hindi. It is remarkably adapted to climbing walls and trees and for catching insects. Its skin is dry, granulated, the body is compressed, the head has a prominent helmet and legs are stick-like.

Two toes of its leg come near the other three and this lets the chameleon achieve a great gripping power (zygodactylous condition). Additional security is provided by the long tail which acts like a fifth limb. (Do tyou know that Tanaji, a General in Shivaji’s army used a type of chameleon-ghorpad? He threw the animal up to grab the rampart wall of Raigarh Fort. Using a rope attached to it, he climbed the wall). The eyes of chameleon are also distinct. They are elevated and eyeball can rotate in all directions. Each eyeball can roll independently of the other. By this ability it can see in front with one eye and can look behind with the other at the same time.

The chameleon has a very long tongue (about 1 foot) which is normally rolled up like a tape inside its mouth. It is well-adapted to its preying on insects. The tongue is projected forward with great speed to capture insects which adhere to its sticky tip. To catch a prey the chameleon sneaks in cautiously, in its camouflage, i.e. after taking on the same color as the background. The prey does not realize that its predator is nearby. When the chameleon comes near the prey it shoots out its tongue with lightning speed to catch the insect. Then it rolls its tongue and brings it inside the mouth. It closes its eyes and takes rest.

Change in skin color can also be seen in the hares and weasels of the far northern regions which develop white coats when snow covers their surroundings. Many desert insects, snakes and lizards are sand colored and it is hard to spot them. Bark inhabiting insects commonly have the same colors as that of the background. Insect larvae which live on green vegetation are green. Many invertebrates found in oceans and fish larvae are transparent.

Wall lizard or house lizard (Hemidactylus) can also change its skin color but cannot roll its eyes. It has vacuum pads (adhesive lamellae) on the sole of its feet. This structural adaptation helps the wall lizard in moving upside down on roofs or in scaling walls.

Warning Colors

Some insects like wasps, bees, butterflies are distasteful to their enemies. By peculiar and conspicuous color they advertise their un-palatability.

Protective Resemblance

Some insects and their larvae look like twigs of trees on which they live. Some appear as leaves.

Mimicry

The protective similarity of one species of animal to another in appearance is termed mimicry. It is particularly found in insects. In this, many harmless, palatable species resemble other unpalatable forms. Viceroy butterfly is palatable and harmless which mimics the monarch butterfly, the unpalatable species. A long horned beetle resembles wasps in form and color. By producing hissing sounds and body coloration some nonpoisonous snakes mimic poisonous snakes of the area.

Adaptation Feeding Habits

Different kinds of insects and animals show various adaptations in relation to their food and feeding habits. Houseflies have elongated lower lip with spongy tip. Cockroaches and locusts have cutting and chewing type of mouth parts, bugs and mosquitoes have piercing and sucking mouth parts.

Leech, an ectoparasite, has rasping jaws, suctorial pharynx and a baggy alimentary canal for storing sucked blood. Hirudin is a substance which prevents clotting of blood. It is found in the saliva of leech.

Frogs have a wide mouth with long, fleshy, bifid, sticky tongue attached in front. To catch a flying insect the tongue is shot out with a jerk.

Snakes can swallow much larger prey as a whole. This is possible because their lower jaw is hinged behind to the quadrate bone of the skull which itself is movable attached to the skull. When the mouth is opened, the base of quadrate bone swings forward and depresses the lower jaw. This creates a wide opening. The prey is prevented from escaping by the teeth present in the jaws.