Read The Oceans text version

Spring 2nd Grade: Visit 1

The Oceans

Ask the class what they know about oceans. Use a map to point things out while they are talking. Main points to discuss: > What's the difference between an ocean and a sea? - You've heard of "one world?" Well, technically, all the world's oceans and seas are part of one continuous mass of seawater. But because the ocean is so big, humans have divided it up and named the different parts. There are five oceans and several dozen seas.* Seas are usually smaller than oceans and are partially enclosed by land. But otherwise, they're exactly the same thing. 1. The oceans occupy 2/3 of the earth's surface and make up 97.2% of all the water on earth (vs. lakes and rivers). Use a globe or other visual aide to demonstrate the amount of water this is. 2. Unlike lakes and rivers, the oceans are made up of saltwater. That means that many different kinds of animals live in the ocean than in freshwater. 3. Some parts of the ocean can be up to 2 miles deep. Because the oceans are so deep and big, there is still a lot that people don't know about the oceans and all the different life forms that live there. This is one reason not to pollute the ocean, because we don't know about everything that we are polluting. II. Diversity of Life in the Oceans A. Tell the class that the ocean contains a whole bunch of different habitats inside it, depending on how deep the water is. Briefly tell them what some of the habitats are and how they are different. Bring in a chart of the zones of the ocean to help them visualize what you are talking about. The Ocean Zones: We are going to talk about the top three layers of the ocean where most known animals and plants live. A. Sunlight Zone: The sunlight zone is also called the Euphotic Zone. This zone is the top zone, and it is also the smallest. The sunlight zone is only about 600 feet deep, but ninety percent of the ocean's sea life lives in the sunlight zone. This zone is home to a wide variety of marine life because plants can grow here. Plants can grow here because sunlight can get to the plants in this zone, so the plants can do photosynthesis and grow. Also, the water temperature is warmer than any other zone in the ocean. The sunlight can reach this zone and warm the ocean water, so it is warm enough for fish and other sea life. Sharks, tunas, mackerels, jellyfish, sea turtles, sea lions, seals, and stingrays are a few of the animals that live in the sunlight zone. Oil Pollution: Pollution is a major problem in the sunlight zone. The main kind of pollution that occurs in this zone is oil pollution. The two main causes of oil pollution in the ocean are big ships leaking oil or ships carrying oil crashing into things in the ocean.

B. Twilight Zone The twilight zone is also called the Disphotic Zone. In depth, the twilight zone is about 2,400 feet, making it the second largest zone. As the water becomes deeper, the water pressure becomes higher. Almost no sunlight can reach this zone. Therefore, very few plants can grow here. The only animals that can live here are those that can adapt to very little sunlight, really cold temperatures, and very high pressure. The few animals that can live in the twilight zone are lantern fish, rattalk fish, hatchet fish, viperfish, midwater jellyfish, octopus, and squid. -Many animals that live in the twilight zone have bodies that protect them from predators. The viperfish and the ratchet fish have fangs so they can easily protect themselves and help them eat their prey. Other fish are so thin that when a predator looks at them, they do not even see them! Some fish are colored red and black to blend in with their surroundings. -Some squid and fish can use their bodies to make light with special organs in their bodies called photophores. These photophores give off a greenish colored light, which helps them see. Most fish in this zone don't chase their prey. They wait for their pray to swim by. Then they snatch their prey and eat it. Toxic Pollution: Some of the pollution that causes problems for the amazing creatures of the twilight zone are metals and toxic chemicals. These toxic chemicals settle in the sea, and eventually some of the fish eat these chemicals. Other fish eat these fish that ate the chemicals, and these fish, too, will eventually die because they are putting toxic pollution into their bodies. C. Midnight Zone The midnight zone is also called the Aphhotic Zone. Ninety percent of the ocean is the midnight zone. This zone happens to be the bottom zone, so it is completely dark. Very few creatures in the ocean live in the midnight zone because the water pressure is extreme and it is near freezing down that far. Some of the very few creatures that live down in this zone are angler fish, tripod fish, sea cucumbers, snipe eels, opossum shrimp, black swallowers, and the vampire squids. Because of the lack of plants at this depth, all of the creatures in this zone are predators. They survive by consuming bacteria which grows from the mineral-rich materials and hydrogen sulfide that are given off by underwater cracks in the earth's crust. Since there is no light down in this zone, some fish do not even have eyes. B. Activity: Bring a set of four pictures of different types of marine life. Each picture should correspond to one of the habitats outlined above. (i.e.: a starfish, kelp, shark, and deep-sea fish) Divide the class into groups, each with a picture of their animal or plant. Have each group try to come up with what part of the ocean their animal would live in, what their animal would eat, what would eat it, etc. Have each group share their ideas with the rest of the class. III. Conservation of the Oceans A. For people, the greatest resource of the oceans is fish. People eat fish all around the world. For a long time now, over fishing has been a big problem. People like to eat certain types of fish and they take as many of that type of fish out of the ocean as they want. This can cause there to be so few of that kind of fish in the ocean that it has an effect on the food web. (Remind of what a food web is)

B. Activity: Over fishing. *Best done outside. Choose 3-5 kids to be fishermen; the rest of the kids will be fish. The fishermen stand on the "boat"(one area of room). Allow the fish to swim (walk) around the room. Round 1: 2 minute time limit. Tell each fisherman to go out and catch as many fish as s/he can and bring them back to the boat, they can keep collecting fish until the time is up. If they are done before 2 minutes, note how long it takes. Round 2: 2 minute time limit. Each fisherman is only allowed to take one fish at a time. (You may want to add extra restrictions such as only 2 fishermen out at a time.) Keep collecting fish until 2 minutes is up, but try to make it so there will still be some fish left. Recap: If everyone is able to catch an unlimited number of fish, then that population of fish will get smaller and may become threatened, endangered or extinct. By regulating the number of fish people catch, more fish are able to survive and reproduce. IV. Pollution-Now let's talk about pollution which is even more harmful than fishing. What are toxic wastes? -Toxic wastes are poisonous materials that are being dumped into the ocean. They harm many plants and animals in the ocean and have a huge impact on our health. Toxic waste is the most harmful form of pollution to sea life and humans. When toxic waste harms an organism, it can quickly be passed along the food chain and may eventually end up being our seafood. In the food chain, one toxic organism gets eaten by another, larger animal, which gets eaten by another animal, and can end up being our seafood. Toxic waste gets into seas and oceans by the leaking of landfills, dumps, mines, and farms. Farm chemicals and heavy metals from factories can have a very harmful effect on marine life and humans. Many fishermen believe that the toxic chemicals in the ocean are killing much of the fish population. One of the most harmful chemicals in the ocean is lead. Lead can cause many health problems. It can damage the brain, kidneys, and reproductive system. Lead can also cause birth defects for people. It has been shown to cause low IQ scores, slow growth, and hearing problems for small children. House and car paint and manufacturing lead batteries, fishing lures, certain parts of bullets, some ceramic ware, water pipes, and fixtures all give off lead. Frequently Asked Questions Why is the ocean blue? No one knows for sure. There are several theories as to why the ocean is usually blue. Some scientists believe that when sunlight hits seawater, part of the white light is absorbed and part is reflected. White light is composed of various shades (all the colors in the rainbow). Seawater does not absorb blue light, so the blue light is reflected outwards. Some scientists believe that suspended matter in the sea is responsible for its blue color. What causes waves? Wind is the most common cause of surface waves. The longer the distance a wind blows, the stronger it is, and the bigger the waves. As wind blows over the ocean, it tries to pick up some of the water. Because the surface of the water can not move, it rises. Gravity pulls the wave back down into the ocean. However, the water now has momentum. Water pressure from below pushes the water back up, and the cycle starts again. How far can sunlight penetrate into the ocean? Significant sunlight can only penetrate 100 meters freely. Because seawater is relatively transparent, about 5% of sunlight penetrates to a depth of 262 feet (80 meters). However, if the water contains significant amounts of silt, algae or other factors, the penetration depth can be reduced to 164 feet (50 meters) or less.

How many oceans are there in the world? There is really only one big ocean. One can sail in a boat in every known "ocean" and "sea", which means they are all connected. What are the main "oceans" called? It is generally recognized that there are five main areas in this one big ocean: · · · · · The Pacific Ocean The Atlantic Ocean The Arctic Ocean surrounds the North Pole. It is the smallest "ocean" with only 5.5 million square miles and 4% of the world's water. It is frozen all the time, except at its edges. The Indian Ocean is the third largest area. It covers about 28 million square miles and holds 20% of the world's water. About 90% of the Indian Ocean is south of the equator. The Southern Ocean is where you'll find Antarctica and the South Pole. Some say it is not an "ocean" at all, but the southern part of three "oceans": the Pacific, Atlantic, and Indian.

What are the world's largest seas? 1. The South China Sea 2. The Caribbean Sea 3. The Mediterranean Sea What are the world's largest islands? 1. Greenland, northern Atlantic 2. New Guinea, southwest Pacific 3. Borneo, southwest Pacific 4. Madagascar, western Indian 5. Baffin Island, northern Atlantic

Why is the ocean salty? It is salty because it has a lot of salt in it! Salt is a mineral that is found in soil and rocks, too. Flowing water picks up some salt and carries it to rivers. Rivers carry it to seas. Since this has been happening for millions of years, the oceans now have a lot of salt--about one cup per gallon! Where is the deepest part of the ocean? The deepest place is near the Mariana Islands in the Pacific. The water is over 36,000 feet deep in the Mariana Trench. That's over 7 miles deep. Mount Everest is only 6 miles high!


The Oceans

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