Category Plants & Animals

What Makes Leaves Green?

Leaves don’t seem to do anything at all. But if you could become tiny enough to peek inside a leaf – you would have a surprise!

Sunlight comes into a leaf through the leaf’s skin. Inside, the leaves have a wonderful green substance called chlorophyll. The chlorophyll catches some of the sunlight that falls on the leaf. At the same time, air comes into the leaf through many tiny openings. And water moves up from the roots below.

Leaves are like little food factories. Using sunlight for energy, the chlorophyll changes water and a gas from the air into food for the plant.

Besides green, leaves have other colours, such as yellow and orange. In summer, the green chlorophyll covers the other colours. In the autumn, it sometimes fades. Then you see the other colours.

Picture Credit : Google

What is a plant?

If someone asked you to name a plant, you might say, “a tree”. You’d probably think of many other green and leafy living things, too. But not all plants are green and leafy. Most are, but not all.

So what makes a plant a plant?

Plants usually spend their whole lives rooted to one place. They can’t move around like animals. Most plants produce seeds to make new plants.

Plants also have special kinds of cells. Plant cells have tough, thick walls made of cellulose. And most plants contain a special substance called chlorophyll. Plants use chlorophyll to make their own food with the help of water, air, and sunlight. Animals have no chlorophyll.

Picture Credit : Google

What are the types of plants?

Plants are divided into groups.

Almost all plants belong to the group called seed plants. They’re called seed plants because they make seeds that grow into new plants.

Most seed plants are flowering plants. Flowering plants make their seeds inside flowers. By far, most plants in the world are flowering plants. Other seed plants make their seeds inside cones. Cone-bearing plants are called conifers. These plants include such trees as pines, spruces, and firs. Plants called cycads and ginkgoes (also called maidenhair trees) also are cone-bearing plants. These types of plants have been around for millions of years.

Other plant groups use tiny cells called spores, not seeds, to make new plants. Spore-making plants include ferns, horsetails, and mosses.

Ferns have feathery leaves called fronds. Their spores form on the undersides of the fronds. Horsetails have tall, green stems with a cap on top. They have long, thin leaves. Moss grows like a soft, green furry coat on a tree trunk or a rock. Moss is made up of thousands of tiny plants growing very close together.

Picture Credit : Google

What Is a Living Thing?

Do you know the difference between a living thing and a nonliving thing? You are a living thing. And so are puppies, trees, and mushrooms. Bicycles, rocks, shoes, and tennis balls are nonliving things.

How do you tell living things from nonliving things? All living things have certain features in common. Almost all living things must have food, water, and air. And they are made up of tiny units called cells. Living things also reproduce, which means they can make new living things just like themselves.

The many, many types of living things are also different from one another in important ways. Scientists separate all living things into large groups called kingdoms. Each kingdom is made up of living things that are similar to one another. Each kingdom is different from the other kingdoms.

Most scientists say there are five main kingdoms. Animals make up one of the kingdoms. Most animals move around and get their food by eating other living things. Plants make up another kingdom. The plant kingdom is important to the other kingdoms because plants create the food that most other living things need. The other kingdoms include organisms such as fungi and algae.

Picture Credit : Google

Why does a hermit crab need a shell?

The Mu Koh lanta national park in Southern Thailand had a rather unusual appeal to make to the public. The park authorities requested the public to donate cone-shaped shells they may have to the hermit crabs that have boomed in the last few months in the park. The population of the crustaceans, which protect themselves by wearing and living inside the discarded shells of other animals such as sea snails, has exploded on some islands in the Mu Koh Lanta national park Marine biologists believe the lack of visitors to the park in the backdrop of the COVID-19 pandemic could be a contributing factor. They feel that low number of tourists means fewer activities in the coastal areas, which could have led to the high survival rates of the hermit crabs.

As tens of thousands of hermit crabs thrive on the island, there is a serious shortage for shells. Some hermit crabs, having outgrown their previous homes, have moved into pieces of rubbish such as plastic cans, bottles, or caps. While going without a shell make them extremely vulnerable to their predators, living inside plastic homes is not safe either. The hermit crabs that climb into plastic bottles find the surface too slippery to get traction. Therefore, they cannot climb out of them. A 2020 study found that around 570,000 hermit crabs die annually from getting caught in plastic debris on two tropical islands in the South Pacific.

Plastic debris, in fact, creates a cascade of death for hermit crabs, because when a hermit crab dies, it releases chemical signal to other crabs conveying that its shell is available for occupation. This lures other crabs into the plastic container. One after the other hermit crabs get into the bottle or plastic can thinking they will get their next home, when in reality, it’s their last home.

Have you heard of the vacancy chain?

Hermit crabs begin their lives in larval forms on the seafloor. The larvae eventually metamorphose into small crabs, at which time they must search for their own shells. Hermit crabs are not true crabs – they do not grow their own shells, instead they have hard exoskeleton in the front and soft body in the back, which they protect using the discarded shells of other animals. As the hermit crab grows in size, it must find a larger shell and abandon the previous one.

These social animals display a fascinating behaviour when they are out to look for a new shell. At least 20 individual hermit crabs line up in size order – biggest to smallest – to see if a new shell turns up and who fits into it best. Their curled tail with a hook enables their bodies to fit inside these borrowed shells. Once a member fits into a new shell, it will eject itself from its former calcified castle and the next smallest will take this hand-me-down home, while leaving its older one for another and so on – the aim is that everyone walks away with a new shell that is a better fit than their old one! Scientists call this the vacancy chain.

 

Picture Credit : Google

What are homoeothermic animals?

Living organisms thrive in different kinds of habitats, including acquatic environments. An important factor that helps some creatures adapt to changes in the external environment is the regulation of their internal environment – physiological processes. And body temperature plays a crucial role in this adaptation. As you may be aware, warm-blooded animals – such as birds and mammals – are those that maintain a high body temperature, and this temperature does not change with any change in the environment. On the other hand, cold blooded animals – such as fish, amphibians, and reptiles – tend to have temperatures that change depending on their surroundings. While warm blooded animals are generally called homeotherms, cold-blooded animals are called poikilotherms. And then there are heterotherms. These are creatures – such as some species of birds and mammals – that generate their own body heat but whose temperatures are also regulated by their environment. They have variations in temperature within different regions of their body, and during different times of the year too. In such cases, the body temperature is usually warmest at the core and much lower in the extremities. For example, the feet of penguins are cold to match their surroundings so that their feet are not stuck to the ice they are on. But their core body temperature is conserved by warning the blood returning from the extremities. Also, during winters, penguins are said to have body temperatures lower than normal, and this helps them conserve energy. Though heterotherms are usually small creatures, a study has shown that the king penguin – a large bird weighing about 10 kg – too exhibits heterothermy.

 

Picture Credit : Google