Category Environtal Studies

WHAT ARE THE FUN FACT ABOUT DRAGONFLIES?

Dragonflies are large, fast-flying insects that can dart at speeds up to 60 km per hour. Their four wings move independently of one another and make a rattling sound. Dragonflies can also fly backwards.

1. Dragonflies Are Ancient Insects

Long before the dinosaurs roamed the Earth, dragonflies took to the air. Griffenflies (Meganisoptera), the gigantic precursors to modern dragonflies had wingspans of over two feet and dotted the skies during the Carboniferous period over 300 million years ago.

2. Dragonfly Nymphs Live In the Water

There’s a good reason why you see dragonflies and damselflies around ponds and lakes: They’re aquatic! Female dragonflies deposit their eggs on the water’s surface, or in some cases, insert them into aquatic plants or moss. Once hatched, the nymph dragonfly spends its time hunting other aquatic invertebrates. Larger species even dine on the occasional small fish or tadpole. After molting somewhere between six and 15 times, a dragonfly nymph is finally ready for adulthood and crawls out of the water to shed its final immature skin.

3. Nymphs Breath Through Their Anus

The damselfly nymph actually breathes through gills inside its rectum. Likewise, the dragonfly nymph pulls water into its anus to facilitate gas exchange. When the nymph expels water, it propels itself forward, providing the added benefit of locomotion to its breathing.

4. Most New Dragonfly Adults Are Eaten

When a nymph is finally ready for adulthood, it crawls out of the water onto a rock or plant stem and molts one final time. This process takes several hours or days as the dragonfly expands to its full body capacity. These newly emerged dragonflies, known at this stage as teneral adults, are soft-bodied, pale, and highly vulnerable to predators. Until their bodies fully harden they are weak flyers, making them ripe for the picking. Birds and other predators consume a significant number of young dragonflies in the first few days after their emergence.

5. Dragonflies Have Excellent Vision

Relative to other insects, dragonflies have extraordinarily keen vision that helps them detect the movement of other flying critters and avoid in-flight collisions. Thanks to two huge compound eyes, the dragonfly has nearly 360° vision and can see a wider spectrum of colors than humans. Each compound eye contains 28,000 lenses or ommatidia and a dragonfly uses about 80% of its brain to process all of the visual information it receives.

6. Dragonflies Are Masters of Flight

Dragonflies are able to move each of their four wings independently. They can flap each wing up and down, and rotate their wings forward and back on an axis. Dragonflies can move straight up or down, fly backward, stop and hover, and make hairpin turns—at full speed or in slow motion. A dragonfly can fly forward at a speed of 100 body lengths per second (up to 30 miles per hour).

7. Male Dragonflies Fight for Territory

Competition for females is fierce, leading male dragonflies to aggressively fend off other suitors. In some species, males claim and defend a territory against intrusion from other males. Skimmers, clubtails, and petaltails scout out prime egg-laying locations around ponds. Should a challenger fly into his chosen habitat, the defending male will do all he can to chase away the competition. Other kinds of dragonflies don’t defend specific territories but still behave aggressively toward other males that cross their flight paths or dare to approach their perches.

8. Male Dragonflies Have Multiple Sex Organs

In nearly all insects, the male sex organs are located at the tip of the abdomen. Not so in male dragonflies. Their copulatory organs are on the underside of the abdomen, up around the second and third segments. Dragonfly sperm, however, is stored in an opening of the ninth abdominal segment. Before mating, the dragonfly has to fold his abdomen in order to transfer his sperm to his penis.

9. Some Dragonflies Migrate

A number of dragonfly species are known to migrate, either singly or en masse. As with other migratory species, dragonflies relocate to follow or find needed resources or in response to environmental changes such as impending cold weather. Green darners, for example, fly south each fall in sizeable swarms and then migrate north again in the spring. Forced to follow the rains that replenish their breeding sites, the globe skimmer—one of several species that’s known to spawn in temporary freshwater pools—set a new insect world record when a biologist documented its 11,000 mile trip between India and Africa.

10. Dragonflies Thermoregulate Their Bodies

Like all insects, dragonflies are technically ectotherms (“cold-blooded”), but that doesn’t mean they’re at the mercy of Mother Nature to keep them warm or cool. Dragonflies that patrol (those that habitually fly back and forth) employ a rapid whirring movement of their wings to raise their body temperatures. Perching dragonflies, on the other hand, who rely on solar energy for warmth, skillfully position their bodies to maximize the surface area exposed to sunlight. Some species even use their wings as reflectors, tilting them to direct the solar radiation toward their bodies. Conversely, during hot spells, some dragonflies strategically position themselves to minimize sun exposure, using their wings to deflect sunlight.

Credit : Thought co ?

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WHAT IS HARMFUL TO THE ANIMAL KINGDOM?

Although natural disasters and sudden changes on Earth’s surface, such as earthquakes, volcanoes and wildfires, can hurt the animal kingdom, human-led changes, such as the cutting down of forests, deliberate forest fires, water and air pollution, have also severely affected wild animal habitats across the world.

Earthquakes and tsunamis

According to United States Geological Survey (USGS), each year there are 15-20 major earthquakes worldwide with a magnitude of over 7.0 and over a thousand that measure above 5.0.5 Unlike hurricanes and volcanoes, earthquakes hit without warning.6 In addition to shaking land, they can shake and displace the seabed. Islands and beaches can disappear from subsiding land or double in size because the land surrounding it is uplifted.7 When the ocean floor is displaced, it can create a tsunami, which is a series of high, fast waves that begin quickly, can cross oceans, and can last for days.8 They may be followed by landslides that bury animals alive and destroy their homes9 or floods that can sweep them away.

Volcanoes

There are at least 20 volcanoes erupting around the world at any time, not including volcanoes erupting underwater, which are much greater in number.13 Eruptions can last for months or years, spewing abrasive and toxic lava and ash, causing explosions, and heating nearby water that can boil marine animals alive.

Storms

The wind, rain, and debris from storms injure and kill animals and cause a lot of damage to their habitats, including destroying shelters and contaminating food and water sources. During Hurricane Dorian in 2019, winds reached 295 km per hour. Strong winds and rain can cause broken limbs, head trauma, as well as breathing problems and infections from getting water in the lungs. Animals are displaced and orphaned. Most of these problems would not be fatal if the animals were able to receive care, but in most cases they do not. A few lucky mammals and birds get care if they are blown into urban areas and are found disoriented on someone’s lawn.

Floods

Smaller animals are more vulnerable to drowning or dying in resulting floods and mudslides. Burrowing animals may be safe from smaller disturbances, but torrential rains can collapse their burrows or block the entrances, trapping them or leaving them without shelter. Burrow entrances can be blocked by branches, leaves, stones and other debris moved around by water or wind.

Fires

A single wildfire can kill millions of animals. The flames and smoke of forest fires kill most animals in their path, including many burrowing animals who are too near the surface, and animals who live in rivers and streams as the flames pass over. Even if they survive the fires, the aftermath can leave animals with burns, blindness, and respiratory problems that can be fatal or permanently debilitating. Hurricane force winds can carry embers and ash from a fire up to a mile away, which can trigger new fires. Strong fires generate so much energy that they change the local weather by modifying wind and temperature. The moisture coming off a fire can generate clouds that cause rain.

Credit : Animal ethics

Picture Credit : Google 

WHAT ARE PREDATORS AND PREY?

When one animal kills another for food, it is called predation. The animal which kills is called a predator, and the animal which gets killed is known as prey. Predators often have special skills for hunting, with highly tuned vision, hearing and sense of smell. Many have sharp claws and jaws to grab hold of and tear the body of the prey. Predators can act in a group or can kill alone. At times they hide and wait to catch their prey off-guard in an ambush killing.

Predator and prey evolve together. The prey is part of the predator’s environment, and the predator dies if it does not get food, so it evolves whatever is necessary in order to eat the prey: speed, stealth, camouflage (to hide while approaching the prey), a good sense of smell, sight, or hearing (to find the prey), immunity to the prey’s poison, poison (to kill the prey) the right kind of mouth parts or digestive system, etc. Likewise, the predator is part of the prey’s environment, and the prey dies if it is eaten by the predator, so it evolves whatever is necessary to avoid being eaten: speed, camouflage (to hide from the predator), a good sense of smell, sight, or hearing (to detect the predator), thorns, poison (to spray when approached or bitten), etc.

In this snowy environment, the polar bear is white to avoid being noticed as it approaches the seal, and the seal pup is white to avoid being noticed by the bear.

The fastest lions are able to catch food and eat, so they survive and reproduce, and gradually, faster lions make up more and more of the population. The fastest zebras are able to escape the lions, so they survive and reproduce, and gradually, faster zebras make up more and more of the population. An important thing to realize is that as both organisms become faster to adapt to their environments, their relationship remains the same: because they are both getting faster, neither gets faster in relation to the other. This is true in all predator-prey relationships.

Another example of predator-prey evolution is that of the Galapagos tortoise. Galapagos tortoises eat the branches of the cactus plants that grow on the Galapagos islands. On one of the islands, where long-necked tortoises live, the branches are higher off the ground. On another island, where short-necked tortoises live, the branches are lower down. The cactuses, the prey, may have evolved high branches so that the tortoises, the predators, can’t reach them.

Credit : New England complex system institute

Picture Credit :Google 

WHAT DO WE KNOW ABOUT THE NEW DORMANT BLACK HOLE?

Scientists have achieved yet another historic feat by discovering a dormant black hole. It is for the first time that a dormant stellar-mass black hole orbiting a star has been detected in a nearby galaxy.

This new black hole is nine times the mass of the Sun and revolves around a blue star in the nearby Large Magellanic Cloud galaxy. Researchers have termed it “the first to be unambiguously detected outside our galaxy”. The binary system has been christened VFTS243. This finding is cardinal because it will help us get more insights into what happens during the death of a star and how black hole pairs are formed.

Astrophysicist and the lead author of the new study Tomer Shenar remarked that they have found a ‘needle in a haystack. The study was published in the Nature Astronomy journal.

How it was detected

In a binary system, two stars revolve around each other and when a star dies, it will lead to a black hole in orbit with the other companion star. Scientists detect black holes from the X-ray radiation they emit as they feed on the companion star.

In this case, the scientists found a massive star orbiting something that couldn’t be observed.

Following further studies, scientists found out that it was a dormant black hole.

The stellar mass black holes are formed when a massive star dies and collapses in a supernovae explosion. But strangely, in this particular case, the star that led to the formation of the black hole in VFTS 243 went away without any explosion and literally vanished into a black hole. Scientists have termed it a direct-collapse scenario. This has led scientists to understand that all stars do not end their lives in supernova explosions and it gives insight into how black hole pairs are formed.

What is a Black Hole?

A black hole is a celestial body that has an immensely huge gravitational pull, so huge that nothing escapes it. Not even light can escape it! The black hole grows by accumulating matter that falls in it. An image of a black hole was captured for the first time in 2019.

What is the size of a Black Hole?

The tiniest black hole can be as tiny as an atom but it can have the mass of a huge mountain. The other is the stellar black hole and these can have a mass of more than 20 solar masses, which is 20 times more mass than our sun. And the biggest black holes are christened supermassive. Sagittarius A is a supermassive black hole.

How are Black Holes formed?

Black holes are formed at the end of the life of a big star. When a massive star, say one having more than 20 solar masses, collapses after its nuclear fuel depletes, it will collapse onto itself and become a black hole. This collapse leads to a supernova and a part of the star gets blown off into space.

So will our Sun turn into a Black Hole?

The Sun cannot turn into a black hole. For us, the Sun is big, but on a celestial scale, it is too small to collapse into a black hole! So, our Sun will only turn into a white dwarf.

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WHEN AND WHY IS PAPER BAG DAY CELEBRATED? WHAT CAN WE DO ON PAPER BAG DAY?

World Paper Bag Day is observed on July 12 every year to spread awareness about plastic pollution and encourage the use of environment-friendly alternatives. Use of paper bags, which are easily recyclable, will help reduce plastic waste that takes years to decompose, causing environment pollution.

Remember the 3 ‘R’s? We know this mantra of Reduce’, ‘Reuse and Recycle can help us adhere to a sustainable lifestyle. It’s also our trump card to save the Earth. What if we told you that there is also another lifestyle choice you could make to help the earth breathe, reduce your carbon footprint and regulate the usage of plastic.

Does it come as a surprise that the humble Paper Bag has a day of its own

The first machine

Not much literature is available as to how Paper Bag Day came to be or who started it. But the day gets marked with a flurry of programmes to promote the usage of paper bags. But there is a lot of drama and story behind this bag and how it came to be. Did you know that it was in 1852 that the first paper bag machine was established? This was by American inventor Francis Wolle who patented the first paper bag-making machine. Wolle who was also a priest called it the ‘Machine for Making Bags of Paper.

Later, inventor Margaret E. Knight came up with a machine that could fashion out flat-bottomed paper bags. She patented this in 1870. This invention made a lot of difference enabling the production of flat-bottomed paper bags that could carry groceries.

It is interesting to note that the inventions didn’t stop here! In 1883, another patent was granted. And this was to Charles Stilwell who created the S.O.S bag aka Self Opening Sack. Stilwell named it so because the bags could stand on their own without anyone’s assistance while it was being loaded.

An alternative to plastic

Much has been talked about plastic and single-use carry bags and their detrimental environmental effects. Yet we still find it being used abundantly in marketplaces. People still depend on it out of convenience.

There is an organic solution to tackle this. Paper bags! One can easily create these bags using recycled paper. You must have seen that newspapers are quite often used for making paper bags.

Make your own bags

So, let’s pledge never to use plastic bags and shift to sustainable alternatives such as paper bags or cloth bags.

And try making your own paper bag! Trust us, you will enjoy the process. You can introduce your fellow mates to this bag that can do so much and initiate them to the new craft of making paper bags. Make this sustainable lifestyle choice and be the change!

QUICK FACTS

According to estimates, 100 trillion plastic bags are used worldwide every year.

About 18 billion pounds of plastic find their way into the ocean every year, proving to be life-threatening to marine life. And this plastic stays in the ocean.

According to statistics, over 40% of the plastic produced gets used only once. And they get discarded, ending up as refuse on the Earth, taking years to disintegrate.

In the case of single-use plastic bags, it could take hundreds of years to disintegrate and get turned into microplastics, polluting the environment further. The plastic that we use today could easily stay on even after our journey.

SAY ‘NO’ TO PLASTIC BECAUSE…

It takes centuries to decompose.

It contains many chemicals that pollute the soil and the environment.

It affects food chains; harms water resources, has led to the unnatural death of animals species on land and sea. It is expensive to recycle.

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WHY ARE THE BEACHES IMPORTANT FOR ECOSYSTEM?

Beaches are much more than just recreation – they are integral to the ecosystem and for livelihood. There is thus, a need to preserve them.

Beaches are amazing wonders of nature. But they are not just spaces for recreational activities. They support an incredible diversity of marine life and the livelihood of fisherfolk. They act as a natural barrier between the land and the sea protecting coastal areas from large waves during a storm. Without this barrier, coastal land would be infertile, courtesy, the sea’s salty water.

India has a long coastline of over 7,500 km which includes both sides of the Indian peninsula and the islands. But, did you know that at many places along the coast, the sandy shoreline has been disappearing slowly? As much as 33 per cent of the coastline has been lost in 26 years between 1990 and 2016 alone. This phenomenon, known as coastal erosion is natural and human-induced.

Coasts undergo constant changes due to natural factors, such as rivers flowing into the sea, sediment deposition, tides, storms, tsunamis and more. However, it is human activity that has put our beaches in peril today.

Threatened existence

A beach is formed when a river deposits large amounts of sediment as it drains into the sea. Dams, built along the course of rivers, have disturbed this natural flow of sediment to the coast. Many ports and fishing harbours dotting the coastline have changed the natural pattern of sand distribution along the coast. Sediments have to be removed from time-to-time to maintain ports. But, they are rarely ever replenished, leading to beach erosion.

Rampant sand mining is a huge contributor to coastal erosion. Sand is a common raw material for construction activities, and its growing demand has spawned sand mafias, which routinely take away truckloads of sand from beaches. Then, mangrove forests hemming the shoreline, that bind the sand together and prevent erosion, are being destroyed for building homes factories, and for commercial activities like aquaculture.

Global warming, over the past several decades, has caused glaciers to melt, leading to a rise in sea levels. Rising seas have been slowly engulfing coastal areas. Due to the rapidly warming Indian Ocean, cyclones are increasing in number and intensity on India’s east and west coasts. Severe cyclones cause changes to the coastal geography. Added to this are many illegal constructions that have encroached upon the coastline despite a ban. This has not only endangered coastal ecosystems but also caused large-scale beach erosion.

In the past two decades, the sea has swallowed up large stretches of our coastline, destroying hundreds of homes and forcing families into temporary shelters. With no beach to stop the sea from flooding villages and towns, the govemment built high stone walls to keep the waves at bay. But sea walls seem to have caused more harm than good.

Erosion during the monsoon is natural, but after the rains, the beach gets restored as the sediments that are washed away are returned to the beach But stone walls block this natural movement of sand. They also redirect the waves and cause another area along the coast to erode. Moreover, sea walls block the easy access of fishermen to the sea. In Kerala, over 65 per cent of the coast is now lined with stone walls instead of sand.

Beach restoration

Until 1989, Puducherry had a beautiful beach drawing thousands of tourists each year. It began to erode soon after the construction of a harbour, and disappeared completely within a few years. After unsuccessful attempts to contain the sea with stone walls, Puducherry finally adopted a sustainable plan to restore the beach. A triangular-shaped artificial reef, submerged into the sea, has been able to partially restore it within a year.

Odisha has installed geotextile tubes at Pentha, a small coastal hamlet in Kendrapara district. These tubes acted as an effective barrier and protected the coast during the cyclones that battered the state in the last decade. The beach has been restored here as well.

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