My Science School

Threats

Increasing human population is said to be the greatest threat to these bears. This leads not only to the loss and degradation of the bears habitat but also human-bear conflict. And, this is not good news. Sloth bears tend to avoid humans. However, they can also be intolerant of them when the two meet face to face. And their aggressive behaviour coupled with powerful claws and canines don't help. So, a human-bear conflict may not end well. For instance, a media report says that “in Odisha, between 2014 and 2018, 716 attacks by sloth bears on humans were recorded. Out of the 716 attacks recorded, 627 humans were left grievously injured - with many victims severely impaired for life". Which means, there are retaliatory killings too. Other worrying factors include hunting and poaching for meat and body parts for medicinal purposes. It is said that there are no specific numbers for the deaths of sloth bears. This is of concern because there are only rough estimates for their population, meaning we may not know exactly how many bears live and die, and what sort of conservation mechanism should be put in place to save this vulnerable species. Another reason for concern is that these animals have traditionally been captured and made to perform "dances" for human entertainment. Though this has been largely brought down in India and some of the animals have even been rehabilitated, it is believed to be continuing in places such as Nepal.

Though sloth bears are found in Sri Lanka, Bhutan, and Nepal too, India hosts its largest population in the world. They appear to be extinct in Bangladesh since no sightings have been confirmed in the region for years now. Within India, they are found in many States, including Karnataka. Tamil Nadu, Kerala, Gujarat, Rajasthan, Chhattisgarh, Odisha, and central India. Among the sanctuaries for the species are Ratanmahal Sloth Bear Sanctuary and Jessore Sloth Bear Sanctuary in Gujarat, and Daroji Sloth Bear Sanctuary in Karnataka. According to the Red List of the International Union for Conservation of Nature, it is a "Vulnerable" species.

Sloth bear facts

• Sloth bears are small bears, and usually have a black coat (and sometimes, a brown coat). What helps identify them is their distinctive whitish or yellowish chest patch in the shape of a wide U or Y.


• They are a lowland species, and occupy different types of habitats such as wet and dry tropical forests, savannahs, scrublands, and grasslands.


• These omnivores feed primarily on termites, ants, and fruits. Apparently, they are fond of honey too.


• Cubs stay with their mothers for roughly two-odd years, and for about nine of those months, they ride on their mother's back.

 

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Spiders can’t chew or swallow so how do you think they eat?  They can only eat liquid lunches!  To do this, they inject their prey with poison using their fangs.  The poison turns the insides of insect to a watery goop and the spider just sucks it up.  

Spiders are not miniature vampires; all species, as far as we know, digest some solid parts of their prey. What makes it especially interesting is that the digestion process begins outside the spider, where anyone who wants to look can see how it works.

Put a medium-sized insect in the web of a large orbweaving spider in the garden. You will see the spider bite the prey, wrap it in silk, wait for it to die, then begin to eat. As a first step in eating, the spider will literally vomit digestive fluid over the prey. Then the prey is chewed with the "jaws" (chelicerae), and the fluid is sucked back into the mouth together with some liquefied "meat" from the prey. The spider repeats this process as often as necessary to digest, and ingest, all but the inedible hard parts. What is discarded afterwards is a small ball of residue.

Spiders other than orbweavers may eat the prey's body but discard some of the wings, legs, etc. Spiders with very small (if strong) jaws (such as crab spiders and cobweb weavers) make small holes in the prey and vomit their digestive fluid into the prey's body, the end result being a hollow shell with some or most of the muscles and internal organs digested and sucked out.

 

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Technically speaking, spiders are not insects! Why aren’t they exactly? We’ll look into a few main reasons why spiders and insects are so different. But first, let’s break down what spiders and insects have in common, which is actually quite a bit.

To understand the similarities and differences between spiders and insects, we have to cover a bit of taxonomy. Taxonomy is the science of classifying all living things. Spiders, insects, fish, birds, and humans all fall into the Kingdom Animalia. Pretty much every animal is able to breathe and move, unlike plants and fungi. Additionally, animals are multicellular, unlike bacteria. Let’s dive deeper into the world of taxonomy and discover more about the classification of spiders and insects.

The next taxonomic level down is where spiders and insects lose their similarities. Spiders are in a class of animals known as arachnids. Spiders, scorpions, mites, and ticks are all different kinds of arachnids. Perhaps the biggest difference between arachnids and insects are the number of legs they have. One of the defining characteristics of spiders and other arachnids is that they have 8 legs. Insects, on the other hand, only have 6. This difference may not seem that significant, but it’s one of the most important things that separate these two classes of animals!

Next up is the number of body segments. Spiders have two segments – the abdomen, and the cephalothorax (which is a combination of a head and thorax). Insects boast three distinct segments – an abdomen, a thorax, and a head. Although they serve essentially the same functions, the body segments are another characteristic that spiders and insects do not have in common.

 

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People Who Work with Animals

Do you love animals? There are many kinds of jobs for people who do. A few of those jobs are listed here.

Veterinary surgeons, or vets, keep animals healthy. City vets deal mostly with pets, giving them injections to keep them well. Country vets take care of farm animals, such as cows and horses.

Zoologists study animals to find out where and how they live, how they get along with people and other animals, and how they change over time. Zoologists work in laboratories, zoos, or museums. Or they work at wildlife refuges in the jungle, at sea, or wherever animals live.

Naturalists study nature by watching it carefully. They hike in the country to watch birds, or they visit museums, parks, and zoos. Many naturalists keep notes, sketches, and photographs of everything they see. You don’t have to wait to be a grown-up to be a naturalist! Many areas have nature-study programmes for children.

Game wardens and rangers help protect wild animals in National parks and game preserves. They rescue animals stranded by floods or fire and make sure people obey fishing, hunting, and camping laws.

Farmers and ranchers raise livestock that provide food for people all over the world. Farmers raise such livestock as chickens, pigs, and dairy and beef cattle. Ranchers raise sheep and cattle on huge farms.

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People to the Rescue

Many people around the world are doing all they can to help save animals from becoming extinct. Zoos used to be just a collection of animals kept in cages to amuse people. Today, zoos try to keep the animals happy, too. Many animals are given large areas to live in that feel just like their homes in the wild. Zoos also breed and take care of endangered animals to save them from extinction.

Wildlife reserves and national parks are areas of land where animals and plants can live safely. There are reserves and national parks all around the world.

People help animals in other ways, too. In many countries, laws ban the hunting or catching of certain animals. Often, when animals are put in danger by a crisis, such as an oil spill, people work around the clock to save them.

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Too Much Hunting

Hyenas and hawks, foxes and frogs, spiders and snakes, lions and lizards, dolphins and dragonflies - all these, and many more animals, are hunters. They hunt and kill other creatures for food. Some people think such killing is cruel, but it keeps nature in balance.

People are hunters, too. They hunt for sport and for food. In many cases, hunting does not upset the balance of nature. In many countries, people are allowed to hunt only animals that are plentiful.

But some hunters kill tigers, leopards, otters, alligators, and other rare animals for their fur or skin. They sell the fur or skin to companies that make coats, shoes, belts, and bags from them. Hunters kill rhinoceroses for their horns and elephants for their tusks. They kill as many of these animals as they can for money. In many parts of the world these animals are being wiped out by hunting!

Many governments around the world have passed hunting laws to try to save animals. Hunters who break these laws and are caught have to pay huge fines - or go to prison.

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All around the world, every day, and more people are being born. All these people need somewhere to live and work, and they need food. People take up space. They need space for their farms, their factories, their houses, and their roads. They cut down forests to make room for crops, houses, and roads. Whenever this happens, animal habitats and homes are destroyed. Habitats are also destroyed when people pollute rivers, lakes, and forests with harmful chemicals or other waste.

Tropical rain forests are home to many kinds of animals and plants. But large areas of tropical rain forests are being destroyed each year as people gather lumber, minerals, and other materials. Scientists and other people worry that if much more of the rain forests are destroyed, thousands of species of plants and animals will become extinct.

Dinosaurs were not the only prehistoric animals to become extinct. Millions of years ago, many elephant-like animals roamed the earth. Over the years, these creatures adapted to their changing environment. For example, they developed different kinds of trunks and tusks depending on what kind of food was available. Sometimes the animals could not adapt quickly enough to changes in their environment. When this happened, the animals became extinct.

The moeritherium was among the first elephant-like animals. It lived about 60 million years ago. The moeritherium had neither trunk nor tusks and was about as large as a pig.

The deinotherium lived between 24 million and 2 million years ago. It had backward-curving tusks that grew down from its lower jaw. Platybelodons lived during the same time as the deinotherium. They had huge scoop-shaped teeth in their lower jaws, which were probably used to pull up water plants.

Mammoths lived from at least 4 million to 10,000 years ago. They were enormous animals with teeth like those of modern-day elephants. Mammoths that lived during the Ice Age had long hair on their bodies, which helped protect them from the extreme cold.

Today, there are two kinds of elephants - the African elephant and the Indian elephant, also called the Asian elephant. In a million years, these and many of today’s animals will be gone. There may be many new kinds of animals.

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Of course, there were no people on the earth when dinosaurs were alive. So how do we know about dinosaurs and other animals of long ago?

Sometimes, when a dinosaur died, its body lay on the muddy ground. The soft parts rotted away, but mud covered the bones and kept them from rotting. Over millions of years, the bones and the mud turned into rock. This helped keep them whole. Over many more millions of years, sun and rain wore away the rock around it, leaving the rocky skeleton. These rocky bones and skeletons are called fossils.

Scientists look for fossils such as this and dig them out of the ground. By studying fossils, the scientists can tell what the animal looked like. They can tell what it ate by the shape of its teeth. Often, they can even tell how well the animal could see and hear and smell things.

Some creatures living in the world today look very much like some of the fossils of ancient animals. By studying these creatures, scientists can get an even better idea of life on the earth millions and millions of years ago.

Why Are They Gone?

Just as you change while you grow, the world and the things that live on it change, too. Most scientists believe that the earth has changed many times in the past, and that many kinds of animals have lived on our planet.

Once, there were scaly reptiles as big as houses. Once there were horses no bigger than cats. And, very long ago, no animals of any kind lived on land. All the animals lived in the ocean.

Dinosaurs were very important animals. They ruled the earth for more than 100 million years. They wallowed in great swamps and prowled through hot, damp forests.

Then something happened, and all the dinosaurs died. We don’t know why dinosaurs became extinct.

Some scientists think dinosaurs became extinct slowly. Swamps began drying up. New plants were taking the place of old ones. Perhaps dinosaurs could not live with these changes. Other scientists think Earth was struck by a huge asteroid. The air then filled with dust that blocked out the sun’s rays. Eventually, this changed the climate and led to the death of the dinosaurs.

Perhaps all these things, and others that we don’t know about, caused the dinosaurs to die out. It’s a great mystery.

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Animals in Danger 

Hundreds of years ago, thousands of birds called dodos lived on the earth. But people overhunted them for food and introduced new animal enemies to their habitats. Now there are no dodos. Today, the numbers of polar bears, rhinoceroses, tigers, and many other animals are going down. These animals are in danger. Why? 

• Their homes are being destroyed. 

• People hunt them for their fur, horns, skins, and meat. Some are hunted for sale as pets and some because people think they are pests. 

• Pollution kills them. 

• Growing numbers of people crowd out animals and use up all the land and food. 

• People introduce new animals to a habitat, upsetting the balance of nature. 

Unless people work hard to save them, many other animals will become extinct like the dodo. 

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Food Chain

A field of green grass waves in the wind. A furry rabbit hops by and nibbles the grass. As the rabbit scurries around, an owl perches overhead. The owl swoops down, grabs the rabbit, and flies away to eat it. When it has eaten its fill, the owl leaves part of the rabbit’s body in another field of grass. The rabbit’s body feeds the soil.

It may seem cruel that animals kill and eat one another. But this is just one way in which wild creatures help each other and keep nature in balance. The grass, the rabbit and the owl are part of an important system in nature called a food chain.

All food chains begin with sunlight. Sunlight provides food for plants. Plants are the primary producers in a food chain. They use sunlight, water, and air to produce food to live and grow.

Animals that eat plants are another link in the food chain. They are consumers. Animals that eat the plant-eating animals are also consumers. The rabbit and the owl are consumers.

Tiny living things called decomposers are also part of the food chain. They break down dead plants and animals into parts. These parts nourish the soil in which the plants grow.

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Animals on the Move

When the cold days of winter come, many animals find it hard to find food. So they fly, march, scamper, or swim to warmer places. When spring comes, they fly, march, scamper, and swim back. This movement from place to place as the seasons change is called migration.

Barn swallows, monarch butterflies, ladybirds, caribou, whales, salmon, and lemmings are just a few of the animals that migrate.

When birds migrate, they often fly great distances. Sometimes they cross oceans and continents. In spring, they migrate back. Sometimes they return to the same nests they used the summer before.

In winter, caribou leave their summer home in northern North America and begin dangerous journey southwards in large herds. The following spring they journey northwards again.

Lemmings are small mammals that live in northern Europe. They migrate sometimes, too. When there is a lot of food, lemmings have many young. When the food runs out, they migrate. Sometimes they travel along roads and through towns looking for food.

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Sleeping Through Winter

Every autumn, a woodchuck eats large amounts of food, curls up into a ball, and goes to sleep in its underground home. But the woodchuck’s sleep isn’t like your sleep. The woodchuck’s heart and breathing slow down and nearly stop. Its body changes. Most of the time, the woodchuck’s body is warm because it is a warm-blooded animal. But the woodchuck’s body grows cold before it goes into its long winter sleep. As it sleeps, its body lives off the energy from the extra food it ate in autumn.

The woodchuck’s sleep is called hibernation. Ground squirrels, bats, hamsters, hedgehogs, and other warm-blooded animals also hibernate.

Snakes, turtles, frogs, and toads hibernate in a different way. A snake is cold-blooded. Its body is just as warm or as cold as the air around it. So when the weather grows colder, a snake’s body grows colder. The snake tries to get warm by crawling into a hole. But as the weather becomes colder, the snake’s body becomes cold and stiff. Its heart and breathing nearly stop.

When spring comes, the woodchucks and other warm-blooded animals wake up. The snakes warm up, too, and crawl out of their holes. The world is alive again!

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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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