Category Zoology

Millions of years ago, reptiles left water for dry land, but they did not leave water for good. Many reptiles went back to the water, not once, but many times. Reptiles left water in the first place to increase their chances for survival. They went back to water for the same reason. Most of the animal body is made of water. The temperature of lakes, rivers, and seas do not change much. This is an advantage for reptiles as they cannot keep up their body temperature by themselves. Land animals need big bones to support their weight. On the other hand, water can hold animals up. That is why the whale is bigger than the elephant.

However, big water animals find it difficult to move quickly. Water reptiles like the long dead ichthyosaurs solved this problem by swimming like fish. Snakes, crocodilians, and lizards moved their body up and down in waves, or they paddled. Breathing is also a problem for reptiles. The oxygen for breathing is dissolved in the water. Fish breathe by means of gills. Reptiles have lungs which are not suited for making use of the dissolved oxygen. Therefore, some reptiles have modified their body surfaces to make use of small amounts of oxygen dissolved in the water. 

Like our nostrils, reptiles have nasal passages. The nasal passage is lined with tiny hairs. These hairs can sense very small units of substances that are to be smelled. The nasal passages of most reptiles have an opening into the mouth. An organ called the Jacobson’s organs opens into the nasal passages of snakes and lizards. This organ helps snakes and lizards to smell. The sense of smell is very important to reptiles. The sense of taste is closely related to the sense of smell, but it is not as important as the sense of smell, for reptiles.

Pit vipers, rattle snakes, and pythons have a special organ for sensing heat called the pit organ. The pit organ is located on the sides of the head between the eyes and the nose. The pit organ can sense even tiny changes in temperature. The snake senses the body heat of mammals and birds with the help of its pit organ, and it goes for the kill. A rattle snake can strike accurately at a mouse or a man in total darkness, with the aid of its pit organ.

 Have you seen a mimic imitate someone else and make people laugh? Some reptiles are expert mimics, but they do it for a serious reason – to save their lives.

 The harmless milk snake has the banded appearance of the poisonous coral snake. This mimicry happens in areas where the two live together. Outside these areas, the milk snake does not look much like a coral snake.

 The non poisonous Mexican king snake looks like the coral snake, when young. A harmless snake may look like a poisonous snake. This is Batesian mimicry. So, enemies mistake the harmless reptile for the poisonous one, and leave it alone. The scientist, H.W. Bates discovered this mimicry over one hundred years ago.

 Blind legless lizards that live under the ground trick their enemies by displaying their tail. The underside of their tails is usually red or yellow in colour, and looks like an open mouth. The enemy attacks the tail, mistaking it for the head. The tail can withstand injury better than the head, and the life of the lizard is saved.

Lizards may have a tail differently coloured from the rest of their body. When the enemy attacks them, they break off their tail. The tail jumps about on the ground, confusing the enemy, and helps the lizard to make good its escape. 

Many animals play hide and seek. Reptiles hide from their enemies by blending in with their surroundings. Quite a few have a body colour similar to their surroundings. The American vine snake looks and acts like lifeless twigs, vines or creepers. When you touch the snake, it drops to the ground and lies there like a dead twig. Other snakes also try this trick, Coral snakes and some other snakes move their tails. So they look like their heads.

 Some reptiles are able to change their colour to match their surroundings. A reptile may be dark coloured when it lives on dark soil, and light coloured on light soil. The green lizard is a great example. Three kinds of old world geckos combine colour and form to escape the eyes of their enemies. They have greatly flattened bodies and tails, and bark like colour patterns. Natural protective colouring is known as camouflage. 

Snakes live under rocks, in burrows, or they may be sand swimmers. A few snakes live in holes in the ground. There is very little food underground. Therefore, they crawl out of their hiding places at night, and hunt for their food. A well made burrow of one animal often attracts other animals. The burrow of the gopher tortoise in the South Eastern United States is inhabited regularly by rattle snakes, indigo snakes, two kinds of lizard, the gopher frog, various small mammals, and a number of insects.

Anthills and the nests of termites also have snake and lizard guests. The reptiles of Central America occasionally shelter in the burrows of leaf cutting ants, armadillos, and those of poisonous spiders called tarantulas. 

 Snakes and Lizards are quite different, even though they belong to the same order of reptiles. Lizards walk on their legs, while snakes wriggle on their bellies. They hear differently. Lizards hear sounds in the air through two external ear openings, while snakes hear vibrations in the ground through their skull bones. Lizards have eyelids while snakes have none, which is a reason why most people are frightened of snakes.