My Science School

We all know what a meadow is. But most of us wouldn't know they exist on the seafloor too. Seagrass meadows are among the world's least known ecosystems. Yet these underwater gardens are crucial to our survival - they are among the most important carbon reservoirs on the planet

Seagrass is a flowering aquatic plant closely related to the flowering plants on land. Seagrasses have long green, grass-like leaves, and are found in shallow salty and brackish waters in many parts of the world

Seagrass meadows support a wide range of marine species such as fish, turtle and dugong. They help prevent beach erosion and mitigate the impact of destructive storm surges. They absorb CO2 and exude oxygen. They also clean the ocean by soaking up polluting nutrients and improve water quality. Recently, scientists have found that certain species of seagrass also capture plastic debris.

What are Neptune balls?

Posidonia oceanica is a type of seagrass found in the Mediterranean waters. When blades of P. oceanica fall or break off their fibres can form tangled masses in the shape of a rugby ball by the swirl of ocean currents. Called Neptune balls, these balls look like brown clumps of steel wool. And researchers have found that these Neptune balls, as they fomu have a knack for trapping small fragments of plastic and then wash ashore during atoms.

By analysing loose leaves and Neptune balls on four Spanish beaches, researchers found plastic pellets, microbeads and polyester fibres from clothes entangled in half of them. Up to 613 and 1,470 items per kg were found in loose leaves and Neptune balls, respectively.

Scientists who were part of this study estimate that the seagrass balls may collect up to 867 million bits of plastic in the Mediterranean annually.

And that's one more reason to save the seagrass ecosystem from destruction from habitat loss, pollution, coastal construction and overfishing.

 

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Deep sleep or slow wave sleep is the third stage of non-REM sleep. Although the body completes a few cycles throughout the night, the third stage occurs in longer periods during the first part of the night.

In the body, the heart rate and breathing rate are at their lowest during this part of the sleep cycle. The muscles and eyes are also very relaxed, and the brain waves become even slower.

It may be very difficult to wake someone from this stage of sleep, which is when sleep disorders, such as sleepwalking, occur.

This stage of sleep also helps the brain rest and recover from a day of thinking, allowing it to replenish energy in the form of glucose for the next day.

Deep sleep also plays a role in keeping the hormones balanced. The pituitary gland secretes human growth hormone during this stage, which helps tissues in the body grow and regenerate cells.

Importantly, a person has to get enough deep sleep for these functions to take place. The amount of deep sleep that a person has will relate to how much overall sleep they get. Sleeping 7 to 9 hours is the recommendation for most adults, which will usually give the body plenty of time in the deeper states of sleep.

 

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Melatonin is a hormone found naturally in the body. Melatonin used as medicine is usually made synthetically in a laboratory. It is most commonly available in pill form, but melatonin is also available in forms that can be placed in the cheek or under the tongue. This allows the melatonin to be absorbed directly into the body.



Some people take melatonin by mouth to adjust the body's internal clock. Melatonin is most commonly used for insomnia and improving sleep in different conditions. For example, it is used for jet lag, for adjusting sleep-wake cycles in people whose daily work schedule changes (shift-work disorder), and for helping people establish a day and night cycle.

Melatonin's main job in the body is to regulate night and day cycles or sleep-wake cycles. Darkness causes the body to produce more melatonin, which signals the body to prepare for sleep. Light decreases melatonin production and signals the body to prepare for being awake. Some people who have trouble sleeping have low levels of melatonin. It is thought that adding melatonin from supplements might help them sleep.

 

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Circadian rhythms are 24-hour cycles that are part of the body’s internal clock, running in the background to carry out essential functions and processes. One of the most important and well-known circadian rhythms is the sleep-wake cycle.

Newborns do not have a circadian rhythm developed until they are a few months old. This can cause their sleeping patterns to be erratic in the first days, weeks, and months of their lives. Their circadian rhythm developsTrusted Source as they adapt to the environment and experience changes to their bodies. Babies begin to release melatonin when they are about three months old, and the hormone cortisol develops from 2 months to 9 months old.

Teenagers experience a shift in their circadian rhythm known as sleep phase delay. Unlike in their childhood years with early bedtimes around 8 or 9 p.m., teenagers may not get tired until much later in the night.

Melatonin may not rise until closer to 10 or 11 p.m. or even later. That shift also results in a teenager’s need to sleep later in the morning. Their peak sleepy hours at night are from 3 a.m. to 7 a.m. — or may even be later — but they still need the same amount of sleep as children.

Adults should have a pretty consistent circadian rhythm if they practice healthy habits. Their bedtimes and wake times should remain stable if they follow a fairly regular schedule and aim for seven to nine hours of sleep every night. Adults likely get sleepy well before midnight, as melatonin releases into their bodies. They reach their most tired phases of the day from 2 to 4 a.m. and 1 to 3 p.m.

Older adults may notice their circadian rhythm changes with age, and they begin to go to bed earlier than they used to and wake in the wee hours of the morning. In general, this is a normal part of aging.

 

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Children and adolescents who do not get enough sleep have a higher risk of obesity, diabetes, injuries, poor mental health, and problems with attention and behavior.1-4

How much sleep someone needs depends on their age. The American Academy of Sleep Medicine has recommended that children aged 6–12 years should regularly sleep 9–12 hours per 24 hours and teenagers aged 13–18 years should sleep 8–10 hours per 24 hours.

During the teen years, the body's circadian rhythm (an internal biological clock) is reset, telling a person to fall asleep later and wake up later. This change is likely due to the brain hormone melatonin , which is released later at night for teens than it is for kids and adults. This can make it harder for teens to fall asleep early.

Changes in the body's circadian rhythm coincide with a busy time in life. For most teens, the pressure to do well in school is more intense and it's harder to get by without studying hard. And teens have other time demands — everything from sports and other extracurricular activities to working a part-time job. Using electronics — including phones, tablets, and computers — also makes it hard to fall sleep. Many teens are up late texting friends, playing games, and watching videos.

Early school start times also play a role in lost sleep. Teens who fall asleep after midnight still have to get up early for school, meaning that they might squeeze in only 6 or 7 hours, or less, of sleep a night. A few hours of missed sleep a night may not seem like a big deal, but it can create a noticeable sleep deficit over time.

 

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When we think of unicellular or single-celled organisms, we usually think of microorganisms that are not visible to the naked eye. We may not be wrong in thinking so because most of the unicellular organisms are extremely tiny and can be seen only through microscopes. But there are certain single-celled organisms that are visible to us, and some can grow to be even a foot long. Surprised? Come, let's find out more about one such organism.

They're macroscopic

Single-celled organisms that are visible to the naked eye are called macroscopic unicellular organisms. Specific types of amoeba, bacteria, and algae fall under this category. One such organism is Ventricaria ventricosa. Also known as bubble algae and sailors eyeball, they are considered one of the largest single-celled organisms. Earlier called Valonia ventricosa, this spherical algal species can grow to even five cm in diameter. They are found in the tropical oceans, and are seen in coral rubble.

Though they come in shades of green, in water they appear darker or silver-coloured.

Just like some such single-celled organisms, these algae have just one cell but several nuclei. Meaning, in the original cell, there is division of the nucleus, but not the division of cytoplasm (the thick fluid in the cell). The division of cytoplasm is what gives rise to more cells in multi cellular organisms. The division the nucleus helps the bubble algae grow large enough to be visible to the human eye. In addition, they are also said to have a large central vacuole - a space within a cell that does not contain cytoplasm - which could play a role in their size.

 

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The U.S. president-elect Joe Biden has declared that the U.S. will return to the Paris Agreement and vowed to reach net-zero emission by 2050. China has committed to achieving net-zero carbon emissions by 2060. South Korea, New Zealand, Australia, Brazil, Iceland and scores of other countries and corporates such as Pepsico have all set net-zero goals. A new study shows that climate disaster could be curtailed within a couple of decades if net-zero emissions are reached.

So, what does net-zero mean?

Do not be confused with the word 'zero'. Net-zero emission does not necessarily mean reaching zero emission. Under a net-zero scenario, emissions will still be generated, but this emission must be removed from the atmosphere through measures such as reforestation and artificial carbon sequestering. In other words, net-zero means achieving a balance between the greenhouse gases put out into the atmosphere and those removed. The term "carbon-neutral" is sometimes used instead of net-zero, and they broadly mean the same thing. It's not just countries that can achieve net-zero emissions, even a state, city, company or a single building can also strive to achieve net-zero emissions.

However, climate activists such as Greta Thunberg are demanding for zero emissions, meaning no emissions are produced in the first place.

How can net-zero be achieved?

• By reducing the use of fossil fuels and by adopting renewable energy sources.


• By developing energy-efficient technologies. 


• By adopting massive reforestation or tree-planting measures.


• By investing in technologies such as carbon sequestration that can remove carbon from the atmosphere. Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide underground permanently and safely.

However, no technology or quantity of trees planted could offset the emissions currently generated globally, unless every country and every household is part of this solution.

 

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By now, we are pretty aware of what viruses are capable of. It is time, now, to turn the spotlight on bacteria. Bacteria are microscopic organisms that exist in every environment, both inside and outside organisms. They live on our skin, in our guts and in our mouth. They live with us throughout our life. Bacteria has been on the planet for more than 3.5 billion years, making them the oldest known life-form on Earth. They support plant and animal life and are used in industrial and medicinal industries. While most serve a purpose, some are harmful. Bad bacteria can spoil your food and water, making them unsafe. But don't worry, of all the bacteria in the world, less than 1 % will make you sick.

Bacteria can live in extreme conditions and are capable of doing incredible things beneficial to humanity and the planet. Scientists have been uncovering fascinating abilities of bacteria. There are those that have the ability to generate biofuels, to purify water, to break down plastic, transform CO2 into proteins suitable for human consumption and those that can 'ea? CO2 and thereby reduce greenhouse gas effects. Now, scientists have shown how Geobacter bacteria could not only survive exposure to toxic cobalt but also coat themselves with the metal - like the Iron Man putting on the suit. Scientists believe that this superpower could open the door for Geobacter's application in environmental remediation, especially by removing toxic pollutants from the environment. In fact, Geobacter bacteria are capable of much more. Read on to know them.

What are Geobacter?

• Geobacter are a group of gram negative bacteria. They are rod-shaped and possess flagella and pili. Pili is a hair-like appendage found on the surface of many bacteria and archaea.


• They live in low-oxygen environments such as muddy soil, seabeds or along the banks of rivers.


• The first Geobacter species (Geobacter metallireducens) was isolated from the Potomac River, just downstream from Washington D.C. in 1987.


• Consequently, many species of Geobacter bacteria were discovered, with each having interesting properties.


• All Geobacter consume organic waste and give out electrons, generating electric current in the process.

Novel electron transfer capability

All creatures on Earth use electrons (yes, the negatively-charged particles) in a complex chain of chemical reactions to harness energy. Humans (and most other organisms) get the electrons from sugar in the food we eat and pass them onto the oxygen we breathe through our lungs. That flow of electrons is what powers our bodies. This chemical reaction may vary between organisms but they all have to find a source of electrons, and a place to dump them to complete the circuit.

Bacteria do not have lungs, nor do they 'breathe' in the sense we have come to understand. Geobacter bacteria get their electrons from organic matter. They pass these electrons to metals or minerals (instead of oxygen) in the environment, using protruding hair-like wires. For instance, Geobacter metallireducens, which has been studied extensively, get their electrons from organic compounds and pass them onto iron oxides. They also produce a small amount of electricity in the process using their nanowires.

Nanowires are special hair-like electrically conductive appendages that protrude from the cell's surface (They are different from pili). Made of proteins with metal-like conductivity, these wires are 10,000 times smaller than the width of a human hair! Because of these nanowires, Geobacter metallireducens can be attached to an electrode to produce an electric current. The nanowires conduct electricity and could potentially be used as a sustainable electronic material. In fact, scientists see a future of recycled energy, in which such microbes can be used to power devices such as smartphones using waste as their only food source.

Fight against toxic chemicals

• Geobacter bacteria were the first organisms found to oxidise organic compounds to carbon dioxide. They can convert the organic compounds in oil spills into carbon dioxide, or turn soluble radioactive metals such as plutonium and uranium into insoluble forms that are less likely to contaminate groundwater. This property makes these bacteria useful for cleaning up water and soil that are polluted with oil or dean up sites that are contaminated with radioactive metals.


• In a recent study, researchers made Geobacter sulfurreducens interact with cobalt, a valuable metal used in batteries for electric vehicles and alloys for spacecraft. But cobalt is highly toxic to livings things, including humans and most bacteria. The metal could penetrate the cells of living being and ultimately kill them. But Geobacter was able to escape that fate, and how!


• When exposed to cobalt, microscope images showed, the bugs shrouding themselves in the metal and continuing to thrive. The Geobacter bacteria coat themselves with the metal, without letting it penetrate their cells. "They formed cobalt nanoparticles on their surface. They metallize themselves and it's like a shield that protects them. It's like Iron Man when he puts on the suit," said the lead researcher.


• The researchers concluded that the bacteria could eventually be put to work extracting cobalt from discarded lithium-ion batteries for reuse, or to soak it up in the environment. The next steps in the research are to investigate if Geobacter could also soak up other toxic metals, in particular, cadmium.

 

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Animal Partners

Hungry crocodiles usually try to eat birds that come near them. But one kind of bird can walk among crocodiles safely. In fact, this bird can lay its eggs in crocodile nests!

A bird called the water dikkop eats insects that disturb crocodiles. The bird gets an easy meal and the crocodile becomes more comfortable. So the birds are really helping the crocodiles. Maybe that’s why the crocodiles don’t harm them.

Little fish called wrasses help many other bigger fish. Tiny worms often fasten themselves to a fish and make sores on its body. When this happens, the fish goes to a coral reef where a wrasse lives. The little wrasse hunts all over the fish’s body and eats the worms.

A European fish called a bitterling teams up with certain freshwater clams. The female bitterling lays her eggs in the clam. When the baby fish leave the shell, clam larvae are buried in their skin. After the clam larvae have grown a bit, they leave the fish and sink to the bottom of the pond or river. The clam provides a safe place for the fish to lay its eggs, and the fish helps spread baby clams along the pond bottom.

The water dikkop, the wrasse, and the bitterling all get something from the animals they help. Some get food as a reward for getting rid of annoying pests. Others help each other reproduce.

Warning!

Have you ever wondered what animals is “saying” when they tweet, squeak, mew, or bark?

Sometimes, animals make sounds to find a mate. But other sounds are calls for help or cries of danger. A dolphin that is hurt makes a high whistling noise to get the attention of other dolphins. The other dolphins use their backs and flippers to keep the injured dolphin near the top of the water so it can breathe.

Some animals “talk” without using any sounds. Deer and many other animals mark their territory by rubbing a special scent on trees or bushes. Glands in the faces of some male deer give off a scent that warns other males to stay away.

Other animals communicate by changing their body positions. Whenever two wolves in the same family meet, they use their bodies to show which wolf has a higher rank, or position. The high-ranking wolf stands straight, holds its tail high, and points its ears forwards. A low-ranking wolf crouches, holds its tail between its legs, and flattens its ears.

Song and Dance

Have you ever seen fireflies flashing on a summer night? If so, you’ve seen male fireflies looking for mates. The male firefly flashes his light to attract a female. Animals use all sorts of things—light, colourful feathers, and even food—to attract mates.

The male satin bowerbird of Australia builds a kind of house out of grass and twigs. It decorates the house with bright stones, flowers, and seeds. When a female comes near, the male spreads its wings and “dances”.

Other animals make “songs” to attract mates. Crickets and grasshoppers make a loud sound by rubbing their wings together, or by scraping a leg against a wing. Many frogs and toads blow up a large sac under their chin. This makes their croaking sound extra loud.

Some animals use “perfume” to attract a mate. Female silkworm moths release sweet-scented chemicals to attract males. For some females, food is a gift of love. A male tern catches a fish and offers it to the female. Male nursery-web spiders present the female with a captured fly before mating.

Safety in Numbers

A herd of baboons hunts for food at the edge of a grassy plain in Africa. Each baboon is looking and listening every second. There might be a lion creeping through the grass towards the herd!

If a baboon saw or heard something, it would give a loud grunt. Baboon grunts sound almost like someone yelling “Hah!” Then all the baboons would hurry to climb trees. Because of one baboon’s warning, all the baboons would be safe.

Some animals live together in herds. They are safer that way. An animal by itself may not see or hear the enemy that creeps towards it. But if there are many animals watching, there are many more chances that one animal will see or smell danger and warn the others.

Herds of baboons, zebras, antelopes, and deer run when they sense danger. But sometimes a whole herd of animals will fight an enemy.

Sometimes the safest place to be is in a herd. There is safety in numbers!

Animal Pretenders

Sometimes, in the world of animals, it’s eat or be eaten. To stay safe from predators, some animals hide in clever ways or pretend to be something else.

It’s hard to see a green grasshopper on a leaf, a striped tiger in tall grass, or a brown lizard on the bark of a tree. Their colour makes them hard to see in their habitats. Some insects are also experts at hide-and-seek. Their bodies are shaped like leaves or twigs, or even like bird droppings. These ways of blending into the background are called camouflage. It makes the animals hard to find, so they are safe from predators.

Other animals are actors they trick predators into leaving them alone. When the Australian frilled lizard is frightened, it unfolds a big flap of skin around its neck and opens its mouth wide. The small, harmless lizard suddenly looks big and dangerous. The opossum and the eastern hognose snake lie on their back and “play dead” when they feel threatened.

How well some animals can hide or act often decides whether they will be able to look for food or become food themselves!

Animal Armour

If you saw a pangolin you might say it looked like a pine cone with legs and a long tail.

A pangolin is one of the animals that is protected by armour. It’s covered with scales like those on pine cone, only bigger. When a pangolin is frightened, it rolls itself into ball. Then it tucks its head between its legs and covers its stomach with its tail. Its sharp-edged scales stick up. Not even a tiger would dare to bite through it.

The armadillo is another animal in armour. An armadillo is born with soft skin. But as it grows, its skin becomes covered with small, flat pieces of bone. This bony armour covers much of the armadillo’s body. The armadillo protects itself by rolling up into a hard, bony ball that even a wolf finds hard to bite.

Porcupines, hedgehogs, porcupine fish, and sea urchins wear a sort of armour, too. Their bodies are covered with sharp spines that keep other animals from biting them. These animals can’t run fast or fight well. But wearing armour helps they stay alive.

Amazing Animals

Do you know of a mammal that lays eggs? A bright blue lizard with stubby legs? Or a fish that can walk on land? There are millions of different animals, and some are truly fantastic.

The platypus and the echidna are mammals that seem to be part bird. The platypus looks like it has the body of a beaver and the bill and feet of a duck. The echidna looks like a porcupine with a pointy snout. Female platypuses and echidnas feed their young with milk, like all mammal females, but they also lay eggs, like all female birds.

The bright blue lizard called an ajolote looks like a worm with legs. It uses its two tiny front legs to crawl and dig holes.

The walking fish will drown if it stays underwater too long. It has to come to the top of the water to gulp air. Sometimes it even crawls out of the water. It pulls itself along with its fins.