My Science School

No prizes for guessing which is the fastest animal on land. You must have seen images of this iconic creature featured in advertisements of sports bikes and cars. Not surprising, as the cheetah can reach speeds of 112 km/h in just 3 seconds! That's faster than most sports cars in the world today!

Cheetahs are found in sub-Saharan Africa and much more scantily in Asia and Iran. They are medium-sized spotted cats with slender long legs and a dark stripe on both sides of their faces. They have a long tail, a big chest, a narrow waist and large nostrils for greater oxygen intake while running.

The aerodynamic body of the cheetah is built for speed, not stamina. After catching its prey, it needs half an hour to catch its breath before it can eat. This is because the high energy consumption due to running at such a high speed, heats up its body to dangerously high levels. This makes it crucial for the cheetah to rest and cool down after a high-speed chase.

Did you know that the name cheetah comes from the Hindi Word 'chita' which means spotted one? A single cheetah needs a huge range to operate in and due to human encroachment into its territory and excessive hunting, it is greatly threatened. Due to the alarming decrease in its populations in the past few decades, it is listed as 'Endangered' in the IUCN Red List. One could say that the cheetah is sprinting fast towards extinction!

In India the cheetah became extinct in 1952, but thankfully there is still hope. Plans are afoot to reintroduce these iconic cats back in the country in the forests of Madhya Pradesh. Fifty cheetahs from Africa will be reintroduced in India over the next five years. Hopefully, this animal superstar will soon roam our country again.

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The eastern gorilla is the largest living primate, with the average adult male weighing around 160 kg and standing at 1.7 metres. This gorilla has a large head broad chest and long arms. Its fur is black and adult males have a silvery streak down the back. As the gorilla gets older, the silvery streak turns white; much like a human being turns grey. Older males are called ‘silver backs’ because of this.

The eastern gorilla has two subspecies - the mountain gorilla and the eastern lowland gorilla. Both species are found in the Democratic Republic of Congo in Africa but the mountain gorilla is found in Rwanda and Uganda as well. These gorillas eat a lot of foliage in the form of leaves and plants since fruits are not abundantly found in their habitat.

They do most of their foraging in the mornings and late afternoons and prepare nests to sleep in the night. These nests are usually made of leaves laid in a hollow space on the ground. These gorillas live in stable family groups which are led by a dominant male silverback.

Females give birth to young only once in three or four years, as they have to care for the infants for around 3 to 4 years after they are born.

The eastern gorilla is listed as ‘Critically Endangered’ due to large-scale habitat destruction and the introduction of diseases from contact with humans. According to the IUCN, its numbers have reduced by about 70 per cent due to the ongoing political instability in areas that the eastern gorilla lives in and it is difficult for their numbers to pick up once again.

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Have you heard the term 'albatross'? It means an unwanted burden in English. Did you know the term is coined after a giant seabird of the same name?

An albatross is the largest seabird in the world. It has an incredible wingspan that can reach up to 3.35 metres - the longest of any bird. This graceful sentinel of the sky spends most of its life soaring high above the oceans in the southern hemisphere. An albatross lives most of its life out in the open Oceans and may touch land after 5 or 6 years only for the purpose of breeding!

While at sea, they eat krill, fish and rubbish from shipping vessels and sometimes follow ships for many days eating from its discarded waste.

It is this habit that caused it to be immortalized in ST Coleridge's ‘The Rime of the Ancient Mariner’. Here a sailor shoots an albatross that follows his ship and dooms the crew with bad luck. He is forced to wear the dead albatross around his neck as punishment by the rest of the crew. Hence, an albatross around the neck signifies great problem.

The albatross is probably the most loyal bird in the world. It mates for life and its 'divorce rate' is zero! If its mate dies it will not search for another partner. It also has an extremely low reproductive rate, laying just one egg in a year or two!

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The term rodent conjures up images of tiny rats and mice that scuttle through dark holes and leaky pipes in urban sprawls. But did you know that the largest rodent in the world lives in the grassy wetlands of South America is nearly 1.2 metres tall and can weigh nearly 66 kg?

They are called capybaras. These creatures are semi-aquatic and spend much time in rivers. They have partially webbed feet, which helps them swim and dive. They are fast swimmers and can hold their breath for up to 5 minutes under water! This helps them to evade predators such as jaguars and anacondas by diving into water. If all else fails they can bark like dogs to scare off a predator!

They are usually found in large groups and communicate with each other with the help of grunts and whistles. These cuddly creatures are herbivores and eat mostly grass, but will consume fruits, grain and vegetables whenever possible.

They are raised on farms for meat in some countries and their skin is harvested to make high quality leather. They are related to guinea pigs and look quite cute and furry. They are kept as pets in countries like Japan and the U.S.A.

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The Chinese giant salamander can grow up to 1.8 metres in length and weighs 50 kg on average, making it the biggest amphibian in the world. This lumpy, dark brown 'living fossil' has been around for a very long time roughly 170 million years! So long in fact, that it has even seen the dinosaurs come and go!

It is a nocturnal and secretive creature and is very difficult to spot in the wild. It lives underwater and camouflages itself in the rocky beds of streams. It has many loose folds of skin covering its lumpy body; and short stubby limbs. It has no gills and breathes through its skin, which is why it prefers fast flowing mountain streams for better oxygenation.

It preys on fish, frogs and insects. Its eyes are not very effective and it detects prey mainly by vibrations in the water. During the breeding season, the female lays many eggs in an underwater den which is guarded by the male till the young hatch out.

This salamander is sometimes called ‘baby fish’ because its cry sounds like a baby crying. These creatures remained relatively unharmed till the 1970s but rapidly reduced in number after the Chinese started hunting them for meat and medicinal purposes.

Today thousands of salamanders are bred in farms across China to meet the market demand for these products. However, this practice is detrimental to the salamander, as farming introduces new diseases in wild populations. The Chinese salamander, which has survived big extinction events, may finally be wiped off the face of the earth due to human greed. They are currently listed as ‘Critically Endangered’ in the IUCN Red List.

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We now know that the blue whale is the largest sea creature, but it is not a fish. It is a mammal. So, you might ask -which is the biggest fish in the ocean? The answer is the ‘whale shark’. You might further ask - is it a whale or a shark? To answer, the whale shark is not a whale, but a shark. However, owing to its massive size (it is known to reach lengths of more than 12 metres), it has earned the name 'whale' shark.

Like many whales and unlike most sharks, it is a filter feeder. In another deviation from sharks, its mouth is located at the front of its head rather than on the underside of its head. However, like all true sharks it breathes with the help of gills, unlike whales which breathe air like humans do. Also, as with all sharks, its skeleton is made of cartilage.

Larger whale sharks may weigh up to 54,400 kg. It would follow that such enormous sharks would be top predators in the ocean, but the whale shark is a harmless fish. It feeds on tiny organisms called plankton that float in the ocean. It uses its massive mouth, which can stretch up to 1 metre wide; to take in the plankton-rich waters using sieve-like structures called filter pads to separate the food from water.

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When it comes to reptiles, there is none deadlier than the saltwater crocodile. Reaching lengths of 2 metres and weights of 1,000 kgs, this apex water predator is the largest of all reptiles found on Earth. Saltwater crocodiles are hyper-carnivorous, opportunistic predators that will eat anything that they can get their jaws on!

They appear lethargic as they bask on riverbanks or float motionless in the water but are capable of lightning-fast strikes at unsuspecting victims. They usually drag their prey into the water. Armed with a lethal bite which is among one of the most powerful in the world, there is no escaping once a 'saltie' latches onto a hapless victim.

Unlike other crocodiles who are confined to river systems, this crocodile fares very well in the open seas as well. They are able to travel long distances on ocean currents and learn to track the migratory route of their prey with very little prior conditioning. They are known to be very aggressive towards humans and are more likely than other types of crocodile to treat humans as prey.

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As birds go, the ostrich is an exception. For starters it does not fly; it has a rumpled, 'un-streamlined' body with untidy, soft feathers; and two toes on each leg instead of the usual four. It reaches heights of up to 3 metres and weighs around 145 kgs making it the world's largest bird.

It is native to the continent of Africa and is typically found in Africa's savannas, woodlands and plains. The ostrich is an omnivore and eats plants as well as small insects when available. These huge birds have three stomachs. Since they do not have teeth, they swallow pebbles and stones to help digest their food. These stones are stored in one of their specialized stomachs called the ventriculus where the food gets broken down to make it easier to digest. So, the average ostrich rattles around with a belly full of stones!

That's not all. An ostrich egg is the biggest egg in the world weighing about 1.5 kg (that's 23 times the size of chicken eggs). It has the largest eyes of any land animal. It is also called the ‘camel bird’ because, like a camel, it has a long neck, prominent eyes, sweeping eyelashes and a jolting walk. Additionally, the ostrich can tolerate high temperatures and go without water for long periods of time.

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Can you imagine a creature longer than three buses, heavier than 33 elephants, with blood vessels so gigantic that you could swim around in them, a heart as big as a car and a tongue as heavy as a pick-up truck? This creature has the unique distinction of being the largest animal EVER to have lived on Earth. Meet the blue whale.

This blue-grey leviathan weighs a whopping 130,000 kg and can grow over 33 m long! It has a long, streamlined body, powerful tail, small dorsal fin and yellowish underside, giving it the nickname ‘sulphur bottom’ whale. Considering its enormous size, one would imagine it to be a top predator with brutal, fearsome teeth to shred its victims, but the blue whale is a gentle giant that feeds mainly on tiny shrimp-like crustaceans called krill.

The blue whale is also called baleen whale because it has unique fibrous plates called ‘baleen’ plates instead of teeth in its mouth. While eating, the blue whale gulps a huge amount of water into its mouth and then expels it back out through these baleen plates which act like hairy nets that capture the krill within. It can eat up to 4000 kilograms of krill every day!

Interestingly the blue whale is not only the largest animal on Earth but also the loudest! Its call may be heard for hundreds of kilometres around!

Sadly, this powerful, yet peaceful creature has been hunted almost to extinction.

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You probably already know that the elephant is the largest land animal found on Earth, but did you know that some species of elephants are bigger than the others? The African bush elephant or African Savannah elephant is larger than its Asian counterpart and has the distinction of being the largest (and heaviest) land animal on Earth. Adult males reach a height of 4 metres and weigh up to 6000 kg!

African bush elephants prefer open savannah or grasslands and are found in southern and eastern African countries like Botswana, Zimbabwe, Tanzania, Kenya, Namibia, Zambia and South Africa. They are easily distinguishable from Asian elephants by their larger, fan-shaped ears and front legs.

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Adult male polar bears stand tall at an average length of 3 metres! They also pack quite a punch at 700 kgs! These features make them the largest land carnivore in the world. The only other close competitor is the Kodiak bear, a sub-species of brown bear found in Alaska.

Did you know that unlike other bears, polar bears are considered marine mammals! This is because they spend most of their time in the freezing cold waters of the Arctic Ocean hunting, swimming and playing. For this reason, they are also called sea bears or ice bears. They are only found naturally in 5 countries - the United States, Canada, Greenland, Russia and Norway.

Polar bears are excellent swimmers. They can swim for hundreds of kilometres at a stretch. They have huge paws, which helps them to swim effortlessly. Their high body fat count also helps to keep them afloat and stay warm in the freezing Arctic!

If you thought polar bear fur was white, you would be mistaken. Polar bear fur is actually colourless and translucent. It allows light to pass through it and appears to be white due to the reflected white light around it. This is a great adaptation as this bear does most of its hunting by night.

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