Camels are the only animals with humps. A camel’s hump is a giant mound of fat, Which can weigh as much as 80 pounds (35 kilograms). The hump allows a camel to survive up to two weeks without food. Because camels typically live in the deserts of Africa and the Middle East, where food can be scarce for long stretches, their hump is key to their survival. When camels are born their humps are empty pockets of flexible skin. As a camel grows and begins to form its fatty tissue reserves, the humps begin to fill out and take shape.
The humps also come in handy for humans who have domesticated the camel. For thousands of years, people have used these strong, resilient creatures for transportation and for hauling goods. The two-hump, or Bactrian, camel was domesticated sometime before 2500 B.C.E., probably in northern Iran, northeastern Afghan – istan, and northern Pakistan. The one-hump, or Dromedary, camel was domesticated sometime between 4000 and 2000 B.C.E. in Arabia.
All living things need water to survive. Without water, the human body stops working properly. Water makes up more than 50 percent of your body weight and a person cannot survive for more than a few days without it. Water flushes toxins out of your organs, carries nutrients to your cells, and provides a moist environment for ear, nose, and throat tissues.
Water is also in lymph, a fluid that is part of your immune system, which helps you fight off illness. You need water to digest your food, to get rid of waste, and to sweat. Too little water in your body leads to dehydration, and it can make you tired and unable to function. Your body gets water from drinking it, but lots of foods, such as fruits and vegetables, contain water too.
Internet search engines are like computerized card catalogs at libraries. Viewed through a Web browser with an Internet connection, they provide a hyperlinked listing of locations on the World Wide Web according to the requested keyword or pattern of words submitted by the searcher. Search engines use computer software called “spiders” or “bots” to search out, inventory, and index Web pages automatically.
The spiders scan each Web page’s content for words and the frequency of words, then stores that information in a database. When the user submits words or terms, the search engine returns a list of sites from the database and ranks them according to the relevancy of the search terms.
Scientists often compare Earth to an onion because the planet is made up of many layers of rocks of different densities. On the outside, there is a think crust of hard, cold rock, which is about 4 miles (7 kilometers) thick under the oceans and 22 miles (35 kilometers) thick under the continents. The crust—the layer we live on—surrounds a hard, rocky surface that marks the top of the mantle, called the lithosphere. Most of Earth is made of its mantle, Which goes almost halfway down to Earth’s center.
At the very center is Earth’s core, which has a center of solid iron and nickel about the size of the Moon (called the inner core) and a molten exterior (called the outer core). The temperature of Earth increases about 36 degrees Fahrenheit (2.2 degrees Celsius) for every 0.62 miles (1 kilometer) down you go, reaching temperatures as high as 11,000 degrees Fahrenheit (6,093 degrees Celsius) at its center.
There is no way specific way to place an order for a baby brother or a baby sister. The gender (boy or girl) of a baby is determined by whether the father’s fertilizing sperm has an X or a Y chromosome. An X chromosome will lead to a girl, and a Y to a boy. (Mothers always contribute an X chromosome.) Although scientific methods are available to help parents organize their chromosomes and take advantage of the fact that the “boy” sperm has less DNA than “girl” sperm, they can be expensive and unreliable. One method, called the Shettles method, recommends that if parents want a girl, they should plan to make a baby right around the time of ovulation.
At this time, the egg is as far away as possible from the incoming sperm so the long-distance runners of the sperm world, the X sperm, have a better chance of making it to the egg. For a boy, the method suggests that parents plan to make a baby about two to four days after ovulation. That way, the short-distance sprinting Y sperm can make it to the egg first. Many doctors say that although this method is based in science, it is no guarantee that a couple will have a baby boy or a baby girl.
The Joshua tree is a desert tree that grows in southwestern North America, in California, Arizona, Utah, and Nevada. A native of the Mojave Desert, these droughttolerant trees thrive in the open grasslands of California’s Joshua Tree National Park. The Mormon pioneers named this tree after the prophet Joshua, because its extended branches resembled the outstretched arm of Joshua as he pointed with his spear to the ancient city of Ai. The trees are twisted and spiky, with tough leaves, and look a little bit like a tree from a Dr. Seuss book. Joshua trees can grow from seed or from an underground rhizome of another Joshua tree. They grow very slowly, sometimes 3.9 to 7.8 inches (10 to 20 centimeters) in their first few years.
The tallest trees reach about 49 feet (15 meters) tall. The trunk of a Joshua tree is made of thousands of small fibers and does not have yearly growth rings, Which makes it hard for scientists to tell the tree’s age. Although the fragile tree has shallow roots, if it survives the harsh desert environment, it can live hundreds— even thousands—of years.
Living species of sequoias are some of the biggest and widest trees in the world. The tallest trees are the coastal redwoods of California, while the widest ones are the giant sequoias, which have much larger trunks and branches. These trees grow in the Sierra Nevada mountains of Central California at elevations of about 6,500 feet (1,981 meters). The trees have survived for 2,000 or 3,000 years. Some of the largest sequoia trees measure 35 feet (10.6 meters) in diameter and up to 300 feet (91 meters) in height.
Their bark can be 4 feet (1.2 meters) thick! Many are found in California’s Sequoia National Park. The General Sherman, for example, is one of the tallest giant sequoias in the world, with a height of about 275 feet (85 meters).
Living creatures need oxygen to survive, and fish are no exception. Human beings 68 use their lungs to take in oxygen, and fish breathe using their gills. A fish’s gills are full of blood vessels that absorb the tiny particles of oxygen from the water.
The fish sucks the water in through its mouth and squirts it out through its gills; during this process, the gills take the oxygen from the water into the blood vessels. A fish’s gills are not constructed to take oxygen from the air, so they cannot breathe on dry land.
Most adult insects, including bees and dragonflies, have two large compound eyes, made up of separate, sometimes thousands, of lenses. They all point in different directions to give the insect a very wide field of vision.
The lenses also help the insect see movement, enabling it to react quickly to seize its prey or escape danger. You can witness this yourself as you try to swat a fly in your home it’s almost impossible to catch a flying insect!