Have spiders got eight legs???

The Creature Constitution Independence Hall Philadelphia, 1786. None of the creatures in the hall were able to sleep. Every night, the mice would run through the spiders' webs. Then the spiders would chase the mice. The crickets would chirp all night. The pigeons in the clock tower would start singing early in the morning. Everyone was tired and unhappy. Maddy the Mouse had the biggest ears in the hall. She heard everything. She worried that no one would ever sleeр. Then the humans began meeting in the hall. Maddy sneaked into the room and listened as they talked. They needed something with rules that everyone would follow. They called it a constitution. Maddy thought a constitution was a great idea. She called a meeting. Every creature came. There were so many animals that they could barely move. "The humans have a great idea," Maddy said. "They are writing a constitution. We should have our own constitution." "What's a constitution?" asked a pigeon. "It's a list of rules for us to live by," Maddy said. "We need rules so we can all sleep." All the creatures agreed. "There are too many of us to talk about the rules right now," Maddy said. "Each group should pick five creatures to talk for them at a meeting tomorrow. They will decide what the new rules will be." The groups each went back to where they lived. They picked animals to speak for their group. The next day, the chosen creatures met. Everyone listened to each other's problems. When the groups started to argue, Maddy reminded them to work together. Each group then shared the rules that they thought would let everyone sleep better. They came up with rules that everyone could agree on. Maddy had found a way for them to all work together. The creatures asked Maddy to be their leader. They would bring new problems to Maddy and the other groups. The night they signed their constitution, the creatures in the building all had a good night's sleep.

Cohesion and Adhesion Water molecules stick to each other as a result of hydrogen bond- ing. An attractive force that holds molecules of a single substance together is known as cohesion. Cohesion due to hydrogen bonding between water molecules contributes to the upward movement of water from plant roots to their leaves. Related to cohesion is the surface tension of water. The cohe- sive forces in water resulting from hydrogen bonds cause the mol- ecules at the surface of water to be pulled downward into the liquid. As a result, water acts as if it has a thin “skin” on its sur- face. You can observe water’s surface tension by slightly overfill- ing a drinking glass with water. The water will appear to bulge above the rim of the glass. Surface tension also enables small crea- tures such as spiders and water-striders to run on water without breaking the surface. Adhesion is the attractive force between two particles of differ- ent substances, such as water molecules and glass molecules. A related property is capillarity (KAP-uh-LER-i-tee), which is the attrac- tion between molecules that results in the rise of the surface of a liquid when in contact with a solid. Together, the forces of adhe- sion, cohesion, and capillarity help water rise through narrow tubes against the force of gravity. Figure 2-11 shows cohesion and adhesion in the water-conducting tubes in the stem of a flower. Temperature Moderation Water has a high heat capacity, which means that water can absorb or release relatively large amounts of energy in the form of heat with only a slight change in temperature. This property of water is related to hydrogen bonding. Energy must be absorbed to break hydrogen bonds, and energy is released as heat when hydrogen bonds form. The energy that water initially absorbs breaks hydro- gen bonds between molecules. Only after these hydrogen bonds are broken does the energy begin to increase the motion of the water molecules, which raises the temperature of the water. When the temperature of water drops, hydrogen bonds reform, which releases a large amount of energy in the form of heat. Therefore, during a hot summer day, water can absorb a large quantity of energy from the sun and can cool the air without a large increase in the water’s temperature. At night, the gradually cooling water warms the air. In this way, the Earth’s oceans stabilize global temperatures enough to allow life to exist. Water’s high heat capac- ity also allows organisms to keep cells at an even temperature despite temperature changes in the environment. As a liquid evaporates, the surface of the liquid that remains behind cools down. A relatively large amount of energy is absorbed by water during evaporation, which significantly cools the surface of the remaining liquid. Evaporative cooling prevents organisms that live on land from overheating. For example, the evaporation of sweat from a person’s skin releases body heat and prevents over- heating on a hot day or during strenuous activity. Adhesion Cohesion Hydrogen bonds Cohesion, adhesion, and capillarity contribute to the upward movement of water from the roots of plants. FIGURE 2–11 www.scilinks.org Topic: Hydrogen Bonding Keyword: HM60777 mb06se_cols03.qxd 5/18/07 10:47 AM Page 41 42 CHAPTER 2 Density of Ice Unlike most solids, which are denser than their liquids, solid water is less dense than liquid water. This property is due to the shape of the water molecule and hydrogen bonding. The angle between the hydrogen atoms is quite wide. So, when water forms solid ice, the angles in the molecules cause ice crystals to have large amounts of open space, as shown in Figure 2-12. This open space lattice structure causes ice to have a low density. Because ice floats on water, bodies of water such as ponds and lakes freeze from the top down and not the bottom up. Ice insulates the water below from the cold air, which allows fish and other aquatic crea- tures to survive under the icy surface.

Hey, Dr. Binocs! Hey there. Hello, Dr. Binocs. Hello. Oh, hello! Friends, did you spot any kinda difference between these two? I'll give you 10 points if you do! No? Well, don't worry. I'll tell you how they are different from each other. But for that I need to tell you all about the Animal Kingdom! Come with me! Zoom in! The Animal Kingdom is divided into two groups. Invertebrates and Vertebrates. And today, we will talk about the invertebrates. Animals without a backbone are called Invertebrates. Which are further classified into.. Worms! Sea Jellies! Mollusks! Anthropods! And Sponges! Now, let us explore a little into their worlds! Worms! They have long, soft bodies with no legs. Oh, and two body openings. You've seen earthworms, right? If you haven't, rush to your nearest garden! Sea Jellies! Jellyfish is a good example here. They have soft and long stinging bodies. Stinging because they use their stingers to stun their prey.. ..before pulling them into their stomach. Mollusks! They have soft and warm bodies. Many of them have hard shells, like the snail. Other examples are Octopus and Squid. Anthropods! These animals form the largest group of the Invertebrates. They have their skeleton on the outside of their bodies. Creepy crawlies such as cockroaches, spiders are anthropods. Sponges! They generally live in saltwater and don't move from place to place. They filter nutrients and tiny organisms out of water, for food. TRIVIA TIME! The Invertebrates will eat almost anything that was or is alive. 97% of all animal species are invertebrates. Well, that keeps a very tiny space for the vertebrates. So do one thing, check this video out, to know more about them! So this is me zoooming out! Tune in next time, for more fun facts.

As long as the birth rate of a population exceeds the death rate, the population size will continue to increase. At a steady, positive per capita growth rate, the population will add a larger number of indi- viduals with each generation. So, a population can increase rapidly with even a small growth rate. A pattern of increase in number due to a steady growth rate is called exponential growth. The observa- tion that populations can grow in this pattern is called the exponential (EKS-poh-NEN-shuhl) model of population growth. One way to understand the exponential model is to study a graph of population size over time. A graph of exponential growth makes the characteristic J-shaped curve shown in Figure 19-6. With expo- nential growth, population size grows slowly when it is small, but growth speeds up as individuals join the population. The exponen- tial model leads us to predict that the population size will increase indefinitely and by a greater number with each time period. Applying the Exponential Model A scientific model is useful if it helps to predict or explain pat- terns that can be observed in reality. Indeed, the exponential model matches observed patterns of growth of real populations, but only under certain conditions and for limited periods of time. For example, a population of microorganisms can grow exponen- tially if provided with an abundance of food and space and if waste is removed. Figure 19-7 shows the growth of bacteria in a laboratory. However, the exponential model does not apply to most popu- lations. In natural environments, populations cannot grow indefi- nitely because the resources they depend on become scarce and harmful wastes accumulate. Any factor, such as space, that restrains the growth of a population is called a limiting factor. All populations are ultimately limited by their environment.SPECIES INTERACTIONS Just as populations contain interacting members of a single species, communities contain interacting populations of many species. Many species have specific types of interactions with other species. This chapter introduces the five major types of interactions among species: predation, competition, parasitism, mutualism, and commensalism. These categories are based on whether each species causes any benefit or harm to the other species in a given relationship. PREDATION In predation (pree-DAY-shuhn), an individual of one species, called the predator, eats all or part of an individual of another species, called the prey. Predation is a powerful force in a community. The relationship between predator and prey influences the size of each population and affects where and how each species lives. Examples of predators include carnivores—predators that eat ani- mals—and herbivores—predators that eat plants. Many types of organisms can act as predators or prey. All heterotrophs are either predators or parasites or both. Predator Adaptations Natural selection favors the evolution of predator adaptations for finding, capturing, and consuming prey. For example, rattlesnakes have an acute sense of smell and have heat-sensitive pits located below each nostril. These pits enable a rattlesnake to detect warm- bodied prey, even in the dark. Many snakes use venom to disable or kill their prey. A venomous rat- tlesnake is shown in Figure 20-1. Other predator adaptations include the sticky webs of spiders, the flesh-cutting teeth of wolves and coyotes, the speed of cheetahs, and the striped pat- tern of a tiger’s coat, which provides camouflage in a grassland habitat. Many herbivores have mouthparts suited to cutting and chewing tough vegetation. A predator’s survival depends on its ability to capture food, but a prey’s survival depends on its ability to avoid being captured. Therefore, natural selection also favors adaptations in prey that allow the prey to escape, avoid, or otherwise ward off

Brazil Where Is It? Brazil is the biggest country in South America. It covers almost half of the continent. Other countries border it to the north, south, and west. The Atlantic Ocean is to the east. The capital city of Brazil is Brasília. Brasília became the capital in 1960. The city was built to be the capital. It was built in only a few years. People. More than 200 million people live in Brazil. Most people in Brazil speak Portuguese. Most people in Brazil live in cities. Many of these cities are on the coast. Some people live in the country. Land. Brazil has many different kinds of land. It has beaches and tall mountains. It also has flat land covered with water. Brazil is home to the Amazon rainforest. It covers almost half of Brazil. It is the biggest rainforest in the world. The Amazon River runs through the rainforest. It is one of the longest rivers in the world. Celebrations. People in Brazil celebrate Carnaval. The holiday happens during Brazil's summer. It goes on for four days. People dress up and walk in big parades. People play many different kinds of music. The party is one of the biggest in the world. Animals. Many animals live in the Amazon rainforest. Parrots live there. They have colorful feathers. Colorful frogs live there, too. They live on the ground and in the trees. Many ants live in the rainforest. Fire ants and leaf-cutter ants live there. Many spiders live in the rainforest, too. The biggest spider in the world lives there. Conclusion. Brazil is an exciting country. It has big cities. It has forests filled with many animals. What do you like most about Brazil? Brazil. Population: 202,656,788. Land: 8,458,417 sq km (3,265,813 sq. mi.) Capital City: Brasília. Primary Language: Portuguese. Currency: Real.

Wonders of Nature Introduction. The world is full of interesting animals. Some animals look strange or have special skills. Let's look at some of these wonders of nature. Archerfish. Archerfish spit water at bugs. The bugs fall into the water, where the archerfish catch and eat them. Trap-Door Spider. The trap-door spider lives in a tunnel in the ground. Its home has a hidden door made of silk and dirt. The spider hides in its tunnel to hunt. Beaver. Beavers chew through tree trunks. They make dams out of trees, mud, and stones. Chameleon. Chameleons change color to hide themselves. They even change color to show how they feel. Flying Dragon. Flying dragons have skin on their sides that opens like wings. They jump and glide from tree to tree. Leaf Insect. The body parts of leaf insects look just like leaves. These animals blend in well with real leaves on trees. Leaf-Rolling Weevil. The female leaf-rolling weevil rolls a leaf into a cone. She lays her eggs inside the cone. The leaf hides and protects her eggs. Praying Mantis. The praying mantis holds its front legs in a praying position. A mantis has five eyes to help it hunt for food. Mole. Moles dig tunnels to find and eat worms. These animals have tiny eyes, but they are not blind. Sea Dragon. Sea dragons are small fish. They look like ocean plants. Their leafy parts help them catch food and hide from enemies. Conclusion. Interesting animals come in many shapes and sizes. They are all wonders of nature.

 A predator is an animal that hunts, catches, and eats other animals. For example, a spider eating a fly caught at its web is a predator, or a pack of lions eating a buffalo.  A predator attacks and eats its prey. Predators may or may not kill their prey before eating them.  Predators are usually carnivores (meat-eaters) or omnivores (eat plants and other animals).  Predators will hunt other animals for food, for examples of predators are lions, tigers, crocodiles, snakes, wolves, and sharks.  Predators are generally larger than their prey and more powerful; many have claws and paws to hold onto their prey. They usually have large canine teeth to pierce through skin and kill prey.  A prey is an animal hunted and killed for food by another animal.  Many prey animals live in large groups that give them more pairs of eyes to look out for danger.  Many prey animals have a means of protection. This may be a hard shell or spine. They may be poisonous.  Some of the bigger prey animals have horns for protection.  Other clever prey animals like the skunk have a foul smell to squirt at the enemy.

Hello, Spring! Wake up, Timmy! Put on your slippers and look outside. Spring is coming. Off we go! Don’t be slow. Let’s slip down the slide. The spring breeze is cool. What fell on your sleeve? It’s a spotted spider. Hey, spider. Please don’t slip away! Have a spoon of sugar.

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