My Science School

Crocodiles are cold blooded, egg laying reptiles that are at home both on land and water. Their long bodies are covered with horny scales, and supported by four legs, each with five slightly webbed toes. The front legs are slightly shorter than the back legs. Crocodiles have long skulls, and some have narrow snouts, while others have snouts that are broader. Their mouths are lined with wicked looking teeth. Their tails are long and muscular and are used to propel themselves through water… and also to bring down a prey.

            All in all, crocodiles are quite fearsome looking and with just a glance at them you will realize that you should not fool around with them! 

 

In ancient times, the first Greek visitors to Egypt were surprised to see an animal that resembled the krokodilos-one of the small lizards found in Greece. They did not realize that this was a different animal altogether, and so they called it krokodilus too. The word 'crocodile' is derived from this Greek word.

The gharial is a crocodile found commonly in India and Nepal. It gets its name from the Sanskrit word for alligators- 'ghantika'. It is also believed that the name is derived from the word 'ghara' which means 'pot' in Hindi, and that it refers to a swelling around the nostrils of mature male crocodiles.

 Turtles and tortoises lay their eggs in holes dug in the soil, very often in the same spot, year after year. Most species have eggs with hard shells, though some do lay soft shelled eggs. The female first digs a hole, and lays the eggs. She then covers them with soil and grass, using her stomach and her back legs. Each clutch of eggs will have three to five eggs, and each egg is about 4 centimetres long, and weighs about 20 grammes. She will lay several clutches each year- sea turtles can lay up to 200 eggs a year!

Turtles and tortoises need to lay a large number of eggs because very few will survive to hatch into babies. Do you know why? It is because; the eggs are stolen by other animals like hedgehogs, squirrels, rats, foxes, as well as by birds and human beings! 

 The green turtle is a sea turtle whose body is highly adapted for swimming.

The green turtle has a wide, smooth carapace, or shell. It inhabits tropical and subtropical coastal waters around the world and has been observed clambering onto land to sunbathe. It gets its name not from its shell, which is olive or brown in colour, but from its greenish skin. It has flippers that resemble paddles, which make it a powerful and graceful swimmer. 

The Chinese water dragon is a large lizard with a crest of prominent, tooth-like scales from neck to tail, and a raised hump on its neck. It has a green body, but the chin and throat are white, pale yellow, or pinkish. Males become brighter in colour during the breeding season.

 It hunts primarily by ambushing its prey, which comprises invertebrates and small vertebrates such as lizards. However, it also forages actively for food, and may occasionally graze upon vegetation. Females lay multiple clutches of 10-15 eggs throughout an extended breeding season.

 

    A tortoise falls quite often on its back. This usually happens when it crawls between rocks and stones.

 However, it must get on its feet as soon as possible; otherwise it will die, baked in its own shell by the sun. So, it will thrash around with all four legs, trying to get a firm hold on the ground with its long claws.

 If it is not successful, the tortoise will waggle its head rapidly. This usually turns it over a little, and then it will catch hold of a patch of dry grass with its back claws, and pull itself on to its stomach. So, if ever see a tortoise struggling to get on its feet, do give it a helping hand!

 

 Box turtles are land dwelling creatures found in mossy areas of the forest, or other damp habitats. Box turtles have a high, domed carapace or upper shell, and a lower shell or plastron with a hinge between the front and rear parts. When a box turtle is frightened, it pulls its heads, legs and tail into its shell, and slams the carapace and plastron together. It is now safely inside a 'box' formed by the tightly closed shell, and its enemies will find it very difficult to get at it.

 

The Galapagos Islands were discovered in 1535. This group of islands lies at a distance of about 10,000 kilometres off the coast of Ecuador in South America. The Galapagos Islands are named for the huge tortoise that lived on these islands - ‘galapago’ in Spanish means, ‘saddle’ and refers to the tortoise shell. It is believed that long, long ago; these giant turtles must have floated to the island from South America on pieces of driftwood.

 The most impressive facts about the Galapagos giant tortoise is that, they keep growing for 30 to 40 years, reaching almost one and a half metres. These are the largest tortoises in the world. In general, they are the longest living of all vertebrates - that is, animals with backbones- the oldest on record lived for 152 years.

Throughout the 19th century, giant tortoises were valued by sailors as food supply. They discovered that these docile animals could live for months without food or water, flipped on their backs, and stacked in the cargo hold of ships. This gave the sailors a ready source of fresh meat, and thousands of these tortoises were killed.

 

 Although green sea turtles live most of their lives in the ocean, adult females must return to land in order to lay their eggs. Biologists believe that nesting female turtles return to the same beach where they were born. Often sea turtles must travel long distances- sometimes more than 1000 kms- from their feeding grounds to reach this beach. Just how sea turtles find these beaches is not known. Males accompany the females during the migration.

Green sea turtles nest only at night. The female must pull herself out of the water and all the way to the dry sand of the upper beach using only her front flippers- a very difficult task indeed. She then carves out a bottle-shaped burrow. She lays her clutch, which consists of approximately 100 leathery-skinned eggs, in the burrow and covers them carefully with sand. She may lay more than 1000 eggs in one summer, making the species the one that lays the maximum number of eggs.