Category Plants & Animals

Sharks are meat-eating sea fish. Most have sleek bodies and rows of sharp teeth. There are about 375 types, of different shapes and sizes, living in different parts of the world. The dwarf shark is only ten centimetres long, while the whale shark, the biggest of all fish, is 15 metres.

How old are sharks?

Fossils show that sharks appeared more than 350 million years ago, long before the dinosaurs. Megalodon was a huge shark which hunter large prey and probably ate shellfish too. Its teeth were about nine centimetres long.

Amazing! Sharks become sluggish in cool water, and so most prefer to live in warm seas. But the huge Greenland shark, six metres long, enjoys icy water. It lives in the North Atlantic, hunting for fish and seals beneath the pack ice.

Is it true? All sharks are dangerous.

No. In the order of dangerous sharks, the great white is most feared by people. But most sharks are harmless to us, and will only attack if they are disturbed. Other dangerous sharks include the tiger shark, mako, bronze and black-tipped whalers, and hammerhead.

Are sharks different from other fish?

Sharks, and their relatives the skates and rays, have skeletons made of rubbery cartilage. Other fish have skeletons made of bone. A shark’s gill slits are not covered like other fish, but are in a row behind its head.

Sharks such as the mako shark are perfect swimming machines, capable of speeds of up to 75 kph. Their sleek shape means they can move quickly through the water and turn at speed.

Is it true? Sharks never have a break.

No. Sharks living near the surface must swim all their lives to avoid sinking. But other like nurse shark spends most of their time motionless on the seabed. Nurse sharks can pump water over their gills and so they don’t need to keep moving.

Why are sharks darker on top?

Sharks that swim near the surface are dark on top and paler on their undersides. This means they are difficult to see from above or below as they hunt for prey.

Amazing! Most sharks drown if they stop swimming, as no oxygen-rich water is passing over their gills. They also sink. They do not have a swim bladder like other fish. They have a huge oily liver instead, which helps to keep them afloat.

How do sharks breathe?

Like all fish, sharks extract oxygen from the water using their gills. Water enters their mouths, and oxygen is absorbed as the water passes over the red, feathery, blood-filled gills. Most sharks keep moving all the time in order to get a constant supply of oxygen.

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A little gecko from the Caribbean is the world’s smallest lizard. This tiny reptile is only about four centimetres long. That’s about as long as your thumb.

Which is the largest turtle?

The leatherback turtle is about the size of a small car. This giant reptile can grow almost three metres long, from its head to the tip of its tail. It measures nearly three metres across its front flippers. It can weigh almost a tonne.

Is it true? Most poisonous snakes live in Africa.

No. Eight out of ten of the world’s deadliest snakes live in Australia. About 3,000 people are bitten by snakes there every year. Luckily, very few of these snakebites are fatal.

Amazing! At almost a quarter of a tonne, the anaconda from South America is the world’s bulkiest snake. This heavyweight snake lies in sluggish rivers or streams, waiting for prey to come down to drink. Then it grabs its victim in its mouth and squeezes it to death.

Which is the smallest crocodile?

The smallest crocodile is the dwarf caiman which lives in South America. This mini crocodile only grows about 1.5 metres long, about a third of the size of its giant cousin, the massive saltwater crocodile.

The giant reticulated python can measure up to ten metres long. That’s longer than six bicycles standing end to end. No snake could grow longer than 15 metres. It would be too heavy to move.

Amazing! The lizard-like tuatara is the only survivor of a group of reptiles that lived in the time of the dinosaurs. By 65 million years ago, the rest of the group had died out. Only the tuatara was left. Tuataras are only found in New Zealand. Their name means ‘spiny backed’ in the local Maori language.

Is it true? Sea snakes are the most poisonous snakes.

Yes. All sea snakes are poisonous. One of the most poisonous of all is the banded sea snake from around Australia. Its venom is many times stronger than the deadliest land snake. Luckily, this snake rarely bites human beings.

Which is the biggest lizard?

The Komodo dragon is the world’s largest lizard. Males can grow more than three metres long and weigh more than 150 kilograms. These record-breaking reptiles live on a few islands in Indonesia. They are meat-eaters and can swallow deer and pigs whole!

Which reptile lives the longest?

Tortoises live longer than any other animals on land. The oldest tortoise known was a Marion’s tortoise from the Seychelles. When it died in 1918, it was thought to be over 150 years old.

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Snakes can’t hear at all. They have no outer ears for detecting sounds. Instead, they pick up vibrations in the ground through their bodies. Snake charmers make it look as if a snake is dancing to the sound of music. But the snake is actually following the movement of the snake charmer’s pipe with its eyes, ready to attack.

Is it true? Some geckos bark like dogs.

Yes. The barking gecko and the Tokay gecko both bark like dogs. They use their loud voices to attract mates or defend their territory.

Amazing! Crocodiles and alligators are very noisy. They cough, hiss and bellow to attract mates and keep in touch with their group. The American alligator roars like a lion. It can be heard about 150 metres away.

How do snakes smell with their tongues?

Snakes don’t smell things through their noses like we do. They pick up smell with their tongues, which they flick in and out. They can recognise different smells with the Jacobson’s organ in the roof of the mouth.

Which reptile can look in two ways at once?

Chameleons can move each of their large, bulging eyes on its own. This means they can look in two ways at once. When they’re hunting, one eye can look out for tasty insects to eat. The other can watch out for hungry enemies.

Picture Credit : Google

The paradise flying snake can glide for 30 metres or more between the trees. It launches itself from a branch, using its tail to steer. Its body acts like a parachute, trapping air underneath, slowing it down as it floats down and lands on a lower branch.

Amazing! The fastest land snake is the deadly black mamba. There are tales of them overtaking galloping horses. This isn’t true but these speedy snakes can race along at about 20 kph.

Is it true? Snakes once had legs.

Yes. The ancestors of snakes were lizard-like creatures with two pairs of legs. Snakes today do not have legs. Their skeletons are made of a skull, a long backbone and many pairs of ribs. This gives snakes a long, thin shape for slithering across the ground.

Can snakes climb trees?

Many snakes slither through the trees, after birds and insects to eat. They are excellent climbers, with rough scales on the underside of their bodies to help them grip slippery branches.

How do snakes slither across loose sand?

Sidewinders have an unusual way of slithering across loose, shifting sand. The sand makes it difficult to get a firm grip. So they flip their bodies sideways in a series of large loops. It leaves a tell-tale set of lines behind in the sand, like the tracks of a bulldozer.

Picture Credit : Google