WHAT IS A HABITAT ?

A habitat is a place where a plant or animal normally lives. Fish live in water. Perch are fish that live in freshwater habitats. Sharks are fish that live in saltwater habitats .
Other animals live on land. Cattle, antelopes, and buffaloes are animals that live on grasslands. Camels and kangaroo rats like the blazing hot temperature of deserts. Bats, gorillas, and elephants thrive in lush, moist rain forests.
Pine trees can live in cold, snowy habitats. Cactuses can live in hot, dry desert habitats. Water lilies live in freshwater habitats.
There are many kinds of habitats. Some habitats are along seashores. Some are high up in mountains or on flat prairies. Others are in dense forests, in sandy deserts, or in the deep sea. Different kinds of plants and animals live in different kinds of habitats.


HABITAT DESTRUCTION
Habitats are being destroyed around the world. As humans move into new areas, they clear the land to build on. They cut down trees for building materials and fuel. They dry out swamps for farmland. They dam rivers for electricity. The animals in the habitat must adapt to the changes or move elsewhere. If they cannot, they die. Many plants die, too.

WHAT IS A FOOD CHAIN?

A food chain is the way energy goes from one living thing to another through food. Plants are the first step in most food chains.
Plants use the energy in sunlight to make their own food. Plants store the energy in their leaves and stems. Plants are called primary producers in food chains.
Animals eat the plants that use the Sun’s energy to grow. Animals are called consumers. Animals that eat plants are primary consumers. Animals that eat other animals are secondary consumers. Animals store the energy in their bodies.
Energy flows from plants to bigger and bigger animals through the steps of eating and being eaten. Each part of the food chain is directly connected to the other, just like the links in a chain.

WHAT IS A FOOD WEB?
A food web is made of many food chains in a community of plants and animals. There are many tiny animals near the beginning of a food web. There are fewer but larger animals higher up in a food web. There are many more insects than fish in a food web. There are also more small fish than big fish. Human beings are at the very top of the food web. No animals are higher up to make us their steady diet.
Decomposers play important roles in some food webs. Bacteria and fungi are decomposers. Decomposers eat dead plants and animals and cause them to rot and decay. They also eat animal wastes. They break things down into chemical parts called nutrients. The nutrients go back into the soil. Plants take up water and nutrients to make food. Nutrients move through food webs over and over again.

HOW THE SUN’S ENERGY GETS INTO FOOD?
The Sun provides the energy that starts the whole process. A plant uses sunlight to make its own food. The energy is stored in the plant. An insect eats the plant. The insect stores the energy in its body. Then the energy is transferred to a fish that eats the insect. When you eat the fish, your body gets the energy stored in that fish.
When you eat salad, fruits, and potatoes, you take in the energy stored in these plants. When you eat fish, beef, or chicken, you take in the energy stored in these animals. When you eat your dinner, your body is getting energy that first came from the Sun. You use this energy to do your schoolwork. You use this energy to run and play.

Fluke :

Fluke (invertebrate), common name given to members of a class of parasitic flatworm . They vary in length from 0.2 to 165 mm (up to 6y in); most species have flat, elongated bodies, although some blood flukes are nearly cylindrical. The possession of a digestive tract, specialized sensory organs, and, in most species, free-living stages places them closer in their evolutionary history to the free-living flatworms than to the parasitic tapeworms. The mouth of the fluke is situated on the underside and, in most species, near the front. Muscular sucking discs at the rear of the body serve to attach the fluke to the host; in the species that are external parasites (ectoparasites), these suckers are often equipped with hooks. Most species are hermaphroditic—that is, male and female organs are present in the same individual. Flukes that are parasitic on the surface of other organisms have a simple development; species that are internal parasites (endoparasites) frequently undergo a complex development requiring two or more hosts to complete their life cycles.
One endoparasitic species, commonly called the sheep-liver fluke, produces a disease in sheep, goats, and cattle called liver rot. This disease has a high mortality rate and is frequently epidemic in Europe and Australia. The sheep-liver fluke is about 2.5 cm (1 in) in length and has a dark red pigment, much like the liver in which it lives. The eggs leave the body of the animal in its faeces and, if they are discharged in a body of water, hatch to liberate ciliated larvae, called miracidia. Each miracidium swims in the water until it finds a snail in which it can develop. The miracidium burrows its way to the liver tissue of the snail and changes into a spore form, or sporocyst. Within the sporocyst, bodies called rediae develop by budding. These rediae produce more rediae, which then produce new larval forms called cercariae. The cercaria escapes from the snail and usually attaches itself to aquatic vegetation, where it encysts. It remains encysted until a sheep or other mammal swallows it. The cyst wall then breaks down, and the larva migrates to the liver of the host, where it develops into an adult fluke. The life cycle of this fluke is typical of the developmental history of many members of the class.
Flukes occur in most parts of the world where the hosts can thrive. They are parasitic in their adult form in many species of vertebrate animals. Each species of fluke is host-specific (able to parasitize only a few related vertebrates). Flukes commonly known as blood flukes infest the blood vessels in humans, causing the widespread, serious disease schistosomiasis, also known as bilharzia or bilharziasis.
Scientific classification: Flukes make up the class Trematoda. The sheep-liver fluke is classified as Fasciola hepatica. The flukes commonly known as blood flukes are classified in the genus Schistosoma.