My Science School

Scientists at MIT are developing light-emitting plants with particles that absorb light, store some of it, and emit it gradually - a big step towards plant-based lighting.

'Plant nanobionics' involves embedding nanoparticles into plants to give them new abilities. Past work by MIT has created plants that send electrical signals when they need water, spinach that detects explosives, and watercress that glows in the dark.

The team used nanoparticles made of strontium aluminate as the phosphor, to absorb visible or ultraviolet light and then release it as a phosphorescent glow over time. The nanoparticles were coated with silica to protect the plants from damage. Several thousand times smaller than the width of human hair, the nanoparticles were infused into the plants through their stomata (small breathing pores on the surfaces of leaves) and accumulated in a spongy layer called the mesophyll. After about 10 seconds of LED exposure, the plants could emit light for about an hour, with the glow brightest for the first five minutes and then gradually 25 cm diminishing. The plants can be continually recharged for at least two weeks.

The goal is to develop glowing plants that could be used to passively light up streets or other public areas, reducing the energy consumption needed for street lights.

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The Aldabra giant tortoise is a giant tortoise found in the Aldabra atoll, a ring-shaped coral reef, in the Seychelles. It is the largest tortoise in the world. Males grow up to 1.22 metres and weigh around 250 kg while females grow up to 91.44 centimetres and weigh up to 150 kgs!

It is also the longest living animal in the world. Funnily enough, the average age of this tortoise has never been established. This is because they out live the scientists who study them! So far, they have been observed to live till about 150 years.

The Aldabra tortoise is one of the slowest animals on the planet. It is almost ten times slower than other turtles and moves at a ‘speed’ of 1.01 km per hour. It is a very restful animal and sleeps for nearly 18 hours in a day!

The bony, protective shell covering the back of tortoises is called carapace. The Aldabra giant tortoise's carapace is dark grey to black. It lives in grasslands called platin and in scrublands and swamps. It likes to eat leaves and fruits when possible. It sticks out its neck to eat from low-lying branches and is even known to knock down small trees to get to the leaves.

Did you know that the Aldabra giant tortoise has the distinction of being one of the first species in the world to be given special protection to ensure its survival? Charles Darwin himself, along with other leading conservationists of the time, made a case to the governor of Mauritius for its protection.

It is a gentle and placid creature and lives a slow and sedentary life. Perhaps that is the secret of its longevity?

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In a world where speed can be the difference between life and death, sloths are an exception. These creatures move at a pace of 0.24 kilometres per hour or one foot per minute and are the slowest mammals on the planet. Believe it or not, this extreme ‘sloth’ on the part of the sloth is what keeps it safe.

During the day, these chilled-out tree huggers stay in the trees and hardly move at all. This is the reason they go mostly undetected by predators. They also grow a kind of green algae on their coats which helps them to blend into their surroundings. Predators such as eagles and jaguars who detect their prey based on movement simply do not see the sloth and hence, they remain safe up in their trees.

The only time these creatures are vulnerable is when they come down from the trees to poop! Most attacks on sloths happen at this time. But the good news is - they only poop once a week. This is because of their extremely slow metabolism, which means that they do not need to eat much. It also means that food takes about a month to pass through their digestive systems.

Found in tropical forests of Central and South America, the sluggish sloth grows to 76 cm and weighs up to 7.7 kg.

Sloths live for about 25 to 30 years. Females reproduce once a year and give birth to just one pup at a time. Threatened by deforestation and human encroachment, sloth populations across South America are believed to be declining, while the Pygmy sloth is listed as ‘Critically Endangered’.

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Starfish don't move very fast.  They move at an average of about 1 metre per minute, with a maximum speed of about 1.6 metres per minute. The speed of a starfish is directly proportional to the size of the starfish. In other words, the larger the starfish, the faster it can move.

There are 2000 varieties of starfish currently in the world. These beautiful creatures usually have 5 or more arms radiating from a central disc and are some of the most exotic looking creatures in the ocean. Did you know that they are more related to sea urchins and sand dollars than actual fish? This is because they do not have scales, fins or gills. Rather, starfish belong to the Asteroidea class and are called Asteroids! It seems befitting that a ‘star’ would belong to a class that means a heavenly object, doesn't it?

These fascinating creatures use ocean currents to help them move over greater distances more quickly. For shorter distances they use their arms - which have special tubes – to travel. Each of a starfish's arms also has eyes at the end of them! There are some starfish with 40 arms and each arm has an eye at the end. Such a starfish would have 40 eyes! A starfish mostly eats clams, mussels and oysters. It extends its stomach out of its mouth to eat its prey! And finally it can regenerate an arm if it is cut off. Weird, but amazing, isn’t it?

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If you were to dive deep into the ocean and reach the rocky floor below, chances are that you might see an incredibly colourful bed of flower-like creatures called sea anemones. Named after the anemone flower found on land, sea anemones are invertebrates (they do not have a backbone) with soft cylindrical bodies and colourful tentacles on the top that resemble petals.

Most of the time, sea anemones stay attached to rocks or coral, and prey on small fish and crustaceans that swim close to them. However, they are known to occasionally move from their position. But their movement is very slow - about 9.91 millimetres in an hour! To move, a sea anemone uses its pedal disc (or base) to slowly shift along on a rock or coral. It is also able to swim and float.

The sea anemone's tentacles act like its hands. They help it to capture prey and also serve as a defence mechanism. Every tentacle has tiny stinging capsules called nematocysts which shoot out a tiny amount of stinging poison capable of paralysing or killing small animals. The paralysed prey is then moved with the help of its tentacles to its mouth and swallowed whole!

Sea anemones are found throughout the world's oceans, but the most abundant populations are found in shallow, tropical waters. They are threatened by climate change, habitat destruction, disease, pollution, predation and of late, collection and trade. If left undisturbed they can live up to 60-80 years. The oldest sea anemone on record is 100-years-old.

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The Shortfin Mako Shark is found in tropical and temperate seas all over the world. It has a streamlined bullet-like shape and small dorsal fins (as its name ‘shortfin’ suggests) that minimize drag, making it an extremely fast swimmer.

It can grow to a length of 3 metres and weigh around 135 kg.

At speeds of 50 km/h, it is one of the fastest sharks in the ocean. It is metallic blue on top and white below. It has large, well developed eyes and a mouthful of teeth. In fact its name ‘Mako’ comes from the Maori language and means tooth or shark tooth. The Maori tribes of New Zealand prize Mako teeth and use them to make necklaces and traditional jewellery.

The Mako is an extremely aggressive and energetic fish. Anglers, who have experienced a Mako Shark at the end of their line, liken the experience to wrestling with an angry crocodile! A hooked Mako will not give up easily and takes a series of flying leaps into the air struggling with the line. Sometimes it will even land on top of the angler and the boat!

This shark also leads an eventful life in the ocean. It preys on and attacks swordfish and will often enter into a battle with these dangerous adversaries. Mako sharks are often seen with swordfish stabs and puncture wounds in their body and some even have broken pieces of the swordfish bill lodged in their heads!

This deadly and beautiful predator was once abundantly found in the world's oceans. Overhunting by recreational anglers as well as for commercial consumption has brought its population down drastically. It is currently listed as ‘Endangered’ on the IUCN List.

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Did you know that the activity of fishing is not just a livelihood but also a sport? Recreational anglers catch fish not just to consume, but for the thrill of the chase and the challenge of fighting against heavy weight fish that test their abilities to the fullest.

High on every angler's dream ‘game fish’ list is the black marlin. These fish grow up to 5 m in length and can weigh up to 750 kg! In fishermen's language a marlin that weighs more than 450 kg is called a ‘grander’. Also, any marlin heavier than 200 kg is usually a female.

But don't let all that bulk fool you. A black marlin is possibly the fastest creature on earth (except for the peregrine falcon). It reaches an astonishing speed of more than 125 km/h! That's faster than a cheetah! It is able to reach such speeds due to its spindle-shaped body, which is wider in the middle and tapered at the ends. It has a highly rigid crescent-shaped tail which acts like a motor powering it through the water. It also has a spear-like snout or bill that helps it cleave through the water.

One of the top predators of the seas, this fish feeds on tuna, cuttlefish, squid, mackerel and octopus. The black marlin is an elusive fish and is found only in the warm waters of the Indian and Pacific oceans. These speedsters are hard to hook and even harder to reel in. Usually epic battles are fought by the marlin and the angler till one wins; and it's not always the angler! The black marlin is yet to be evaluated by the IUCN as there is little data regarding them.

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The Thomson's gazelle is named after Joseph Thomson, a British explorer and geologist. It is found in Kenya's Masai Mara region and Tanzania's Serengeti region. It is one of the fastest runners in the world along with the cheetah, the pronghorn and the springbok. It reaches a top speed of around 90-100 km/h.

It is a small-sized, elegant antelope which weighs around 25 kg and stands about half a metre tall. It has white rings around its eyes and black stripes down its face and across its flanks. Its horns curve backwards. Males have longer and stronger horns than the females. It prefers open plains and grasslands and feeds on fresh grass, seeds and scrubs. Mothers are very protective of their young. They will headbutt predators like jackals or baboons if their fawn is threatened. Mothers will often hide their fawns in the tall grasses of the savanna to protect them from predators till they are big enough to feed on the grass.

Its major predators are cheetahs but the Thomson's gazelle can outlast a cheetah in a long chase. It can take turns while running fast and will zigzag to frustrate the pursuer. It also demonstrates pronking or stotting - leaping high in the air to display strength and to warn predators.

This slender and swift antelope is hunted for its meat and horns and faces additional stress from habitat loss. Fortunately its population in the wild is still stable and it is listed under ‘Least Concern’ in the IUCN List.

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The African wild dog, also called the African painted wolf, is one of the most   endangered predators in the world. It is about 60 cm tall and weighs around 20 kg. Each dog has a unique mottled coat with irregular patches of red, yellow, white and black.

This species has large rounded 'Mickey Mouse' ears and a white-tipped tail. They have 4 toes on their forelegs unlike 5 toes that the average dog has.

The wild dog reaches speeds of up to 70 km/h and hunts in packs. It typically preys on antelopes like Thomson's gazelle and blue wildebeest. They may also supplement their diet with small rodents, fowl and livestock when available. These dogs have a complex and hierarchic social structure and are deeply cooperative and collaborative with each other.

For instance, they show collective responsibility towards elder members and young pups. Pack members will allow pups to have the first share of a kill and regurgitate food for older pack members if they need it. They also have a democratic system in place for decisions of whether to hunt or not to hunt. However, instead of votes, they show consent by sneezing! So, if enough dogs sneeze, the pack takes the decision to begin its next hunt!

Though they were once abundant, African wild dogs have disappeared from most of their geographic range. These days they are found in the open plains and sparse woodlands of sub-Saharan Africa with the largest populations in Botswana, Zimbabwe, Namibia, Zambia, Tanzania and Mozambique.

Causes for their declining numbers are habitat loss, hunting by other predators like lions and hyenas and diseases like rabies and distemper and the human - wild dog conflict. They are listed as ‘Endangered’ in the IUCN List.

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While it is delightful to learn that antelopes and kangaroos are fast runners, it is a bit daunting to find out that lions are equally fast! A lion can reach a top speed of 81 km/h, so if you are planning on outrunning this magnificent beast, be warned!

When one adds brute strength to lethal speed (a lion weighs about 250 kg and reaches a length of 2.7 or 3 metres), it is no wonder that this formidable predator is undoubtedly and indisputably the 'king of the jungle'.

In real life the lion is mostly found in the grasslands and savannas of Africa. The only population of wild lions that inhabit a forest habitat is the Asiatic lion in the Gir National Park in Gujarat, India.

Lions are quite adaptable and can live in dry areas as well as forested regions. Lions living in desert regions like the Kalahari, have been known to get water from wild watermelons called tsamma melons.

The lion is the only species of cat that will hunt in a group. It can eat 40 kgs of meat in a single sitting! They like to hunt at night as they have excellent night vision. This gives them an advantage over their prey. They also like to hunt during storms as the noise makes it harder for prey to hear them.

Lionesses do most of the hunting for food. Lions have more of a protective role in a pride. Lionesses form well-coordinated groups when pursuing prey. Some will move towards the centre of a hunting group while others move towards the wings. The wing members chase the prey towards the centre. The hapless prey stands very little chance against a pack of lionesses!

Interestingly lions are the only known cat species who roar together with even the young cubs joining in. Prides often roar together to mark their territory. A roar can be heard many kilometres away. Threats to lions include habitat loss, poaching and human-lion conflict. These apex predators are listed under ‘Vulnerable’ in the IUCN Red List.

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The black buck, also called the Indian antelope, is found in parts of western India, eastern Pakistan and in Nepal. This species shows an extreme contrast between males and females. While adult male blackbucks have a distinctive black and white colouring with long, slender, spiralling horns, females have reddish-brown colouring and do not possess horns.

The black buck is one of the fastest animals after the cheetah, pronghorn and springbok, clocking a top speed of 80 km/h. They live in semi-desert regions, scrublands and open woodlands and prefer to feed on grasslands. They are social animals who live in herds of 5 to 50 members. They are shy and alert to danger. When it senses trouble, it jumps in the air and sprints away followed by the whole herd.

Due to habitat loss from developmental work and a long history of being hunted for sport and meat, this antelope is listed as 'Near Threatened' in the IUCN List.

This graceful gazelle enjoys special protection in our country and figures in the national endangered species list. In India hunting blackbuck is prohibited under Schedule 1 of the Wildlife Protection Act of 1972. There are strict laws protecting the black buck. You may have heard of Bollywood actor Salman Khan being convicted in a black buck poaching case in 2018.

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Deep in the lower expanses of Africa, spanning across thousands of square kilometres in north Tanzania, are vast grasslands called the Serengeti. These endless plains are dominated by the blue wildebeest. The wildebeest is a large antelope that belongs to the family Bovidae. It has a cow-shaped head with a pointy beard, and strong curved horns. Its coat has a silver blue shine which gives it the 'blue' in its name.

 The blue wildebeest is responsible for the largest migration in the history of the animal kingdom. The 'Great Migration' as it is called, involves an 800-kilometre trek of 1.5 million wildebeest across the Serengeti in search of greener pastures and water sources.

The wildebeest is joined by hundreds of thousands of zebras, gazelles and other animals in the 'Serengeti Migration', which is listed as one of the seven natural wonders of Africa! However, not so long ago, the wildebeest population in the Serengeti was in danger of extinction. This also threatened the Serengeti ecosystem which depends on this migration for its effective functioning as a carbon sink. The wildebeest consumes excessive vegetation which would otherwise dry up and catch fire in the summer, leading to the release of huge amounts of carbon dioxide into the atmosphere.

Thanks to the collaborative efforts of wildlife groups, the wildebeest was brought back from the brink of extinction and now numbers about 1.5 million in Tanzania. It is listed under ‘Least Concern’ in the IUCN Red List.

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The cheetah is undoubtedly the fastest animal on land but it tires quickly. The prize for the fastest runner over longer distances goes to a goat-like mammal indigenous to North America called the pronghorn.

The pronghorn can reach speeds up to 89 km/h, which it can sustain over a distance of 800 metres and a speed of 56 km/h, which it can sustain for 6 km! So, while the cheetah may get a head start, the pronghorn would likely finish first over a longer distance.

The pronghorn's hooves have two long, pointed toes cushioned to help take the shock when running at high speeds. The pronghorn runs with its mouth open allowing it to take in lots of oxygen to fuel its running muscles. Funnily enough, although they are excellent runners, pronghorns are not good jumpers. If they come across a fence, they will go under it rather than over it.

The pronghorn is native to North America and is literally in a class of its own. It is often called an antelope but it is not classified as one. It is the sole surviving member of the family Antilocapridae. Its closest living member is actually the giraffe! In America it is known by many names – prongbuck and American antelope, among others.

Pronghorns have backward-curving horns which split to form forward-pointing prongs which give the species its name. They graze on a variety of plants and prefer non-woody flowering plants. They can also eat some plants found in the grasslands that are poisonous to cattle and livestock.

Pronghorns have great eye-sight, with a nearly 360-degree field of vision, to help them evade predators such as wolves, and bobcats. The American pronghorn is hunted throughout much of its natural range.

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The springbok is the national animal of South Africa. The name ‘springbok’ comes from the Afrikaans words 'spring' which means jumping and 'bok' which means antelope or goat. Like the American pronghorn, the springbok is one of the fastest animals on the planet. It can reach a speed of 88 km/h. However, unlike the pronghorn which does not know how to jump, the springbok can leap 2 to 2.7 metres high into the air!

This behaviour of jumping high up in the air and landing back on its feet again is called 'pronking'. The springbok does this to impress other springbok or to warn predators. A mid-sized antelope weighing between 27-42 kg, these white-faced, slender, long-legged antelopes feed on grass and shrubs. The male springbok is called a buck while the female is called a doe. Interestingly, the springbok can live without water for many years! In some cases springboks have lived without water their whole lives! This is possible because the springbok feeds on succulents, from which it extracts water.

In earlier times a vast number of springboks would migrate together in search of greener pastures. Such a herd would easily comprise a million animals and the trek would take several days to complete. Such treks are called 'trekbokking' in the Afrikaans language.

Found in south and southwestern Africa, these springing beauties are the national animal of South Africa. They are featured in the currency and postage of that country. They are hunted as well as reared for their horns, meat and attractive coats. Surprisingly, despite the legalized hunting of this animal, springbok populations are increasing.

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A marsupial is a mammal that carries its young in a pouch on its body. Marsupials include koalas, wombats, opossums and kangaroos among others. Of these the largest marsupial of all is the red kangaroo which is found in the open plains of inland Australia. It can grow to a length of 1.6 m with a tail that measures 1.2 m. It weighs about 90 kg.

It belongs to the family Macropodidae which means ‘big foot’ in Latin. It is so named because of its unusually large hind feet. Its feet play a big role in its life, serving as a launch pad to take terrific leaps into the air while running from a predator, or as a weapon to plant powerful kicks at an enemy!

Its predators are mostly wild dogs called dingoes. Kangaroos have an interesting getaway technique if threatened. It will lead its would-be predator to water and dive in. If the predator follows, the cunning kangaroo will suddenly turn around, grab it with its hands and drown it! The hunted becomes the hunter!

But it doesn't always need to use such extreme tactics. Kangaroos can run at 70 km/hr. They can cover 7.6 metres in a single jump and leap as high as 1.8 metres! At such speeds very few predators can keep up with them. Kangaroos are the only animals in the world that use hopping as a means of locomotion! It also uses its tail as a fifth leg using it to balance and provide extra power.

Another interesting fact about them is that they have been observed to be left-handed. Their young are called joeys. When a joey is born, it is only the size of a jellybean! It climbs from its mother's birth canal into her pouch and remains there, drinking milk and growing for nearly 6 months! Now, wouldn't you agree that the kangaroo is an interesting animal?

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