1. SHARKS The shark, who plays an important role in maintaining ecosystems, is a fish that lives in the sea, particularly in the warm waters. Like all fish sharks breathe through their gills. There are about 375 species of sharks. The smallest shark is called the dwarf dogfish, less than 20 centimetres long. The huge whale shark can be more than 15 metres long. Sharks usually eat fish and shellfish, but great white sharks sometimes eat seals, dolphins, whales, and other marine mammals. Sharks are vertebrates, animals with a backbone. However, a shark’s teeth are set into its gums. While eating, a shark often loses teeth. But, there are always rows of new teeth growing behind the first set. As a shark loses teeth, new ones move forward to replace them. 2. MANGROVE MANGROVE A mangrove is a tropical marine tree. Mangroves have special aerial roots and salt-filtering tap roots which enable them to thrive in brackish water. Brackish water is salty but not as salty as sea water. Mangrove trees are commonly planted and found in coastal areas. Mangroves can serve as walls of protection for natural disaster in coastal area like tsunami. Healthy mangrove forests had helped save lives in the Asia disaster tsunami and people tended to respect these natural barriers even more, especially after the tsunami. There are several species of mangrove tree found all over the world. Some prefer more salinity, while others like to be very-close to a large fresh water source such as river. Some prefer areas that are sheltered from waves. Some species have their roots covered with sea water every day during high tide. Other species grow on dry land but are still part of the ecosystem. The times of India reported that rare species of mangrove had been found and was also known as the looking-grass tree, probably because the leaves are silver-coated. Mangroves need to keep their trunk and leave above the surface of the water. Yet they also need to be firmly attached to the ground so they are not moved by waves. Any part of root that appears above the water flows oxygen to the plant under water surface. As the soil begins to build up, these roots proceed to enlarge additional roots that become embedded in the soil. 3. Pygmy Hippopotamus Pygmy Hippopotamus(Choeropsis liberiensis or Hexa protodon liberiensis) is a small hippopotami which is native to the forests and swamps of West Afica, primarily in Liberia, with small populations in Sierra Leone, Guinea and Ivory Coast. The pygmy dense vegetation along streams and swamps and in the rainforests. It sometimes lives in cultivated areas, but the pygmy hippo is shy: it avoids people, as well as other hippos. Each hippo has its own territory. The male's territory is larger than the female's; both mark their territorial boundaries with their droppings. The pygmy hippo feeds mainly when its territory. It changes resting places once or twice a week. 4. TRAINS A train is made up of rail road cars, hooked together and pulled by a locomotive. Locomotives are sometimes called engines. The types of locomotive engines most used today are diesel-electrics. Engines that burn diesel fuel drive generators that make electricity. Powerful electric motors turn the wheels of a diesel-electrics locomotive. There are two types of train, freight and passenger trains. A freight train can have as many as 200 cars hooked together. There are special rail road cars for different kinds of freight. The boxcar has four sides, a floor and a roof. It carries radios, television sets, and boxes of cereal. Refrigerator cars work like your home refrigerator. They are boxcars that are cool inside. Refrigerator cars carry meat, fruit, frozen dinners, and other food that must be kept cold. The hopper car is open on the top or sides. It has a floor on wheels. Flat cars carry lumber, steel beams, huge pieces of machinery, and other big items. Lifting machines called cranes load cargo onto flat cars, Special flatcars carry cars, boats, and trucks. Passenger trains have seats in rows along each side. They are made for long trips. They have seats that can be made into beds at night. Trains that carry passengers over long distances have special baggage cars to carry suitcases. They have dining cars where people can sit down and eat.

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