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Sea Resources
Home Up Reusable Renewable NonRenewable Minerals Sea Resources


Minerals in the Ocean

            One of the minerals in the ocean is the same salt we use on food. This salt is a compound of two elements, sodium and chloride. Chemists call table salt sodium chloride. About 3/4 of the salt in the ocean is this "table salt." The chart lists some of the mineral elements in the ocean and how we use them.

Chemical Uses
Sodium Combined with chlorine for table salt
Magnesium Airplane parts, printing inks, insulating materials, medicines
Potassium Medicines, dyes, fertilizers, paints
Bromine High-test gasoline, medicines, photographic films
Chlorine Bleach, disinfectant

            Gold and silver make up a small part of the minerals of the sea. Yet in a stretch of water one mile long, one mile wide, and one mile deep, there are ninety-three million dollars worth of gold and eight and a half million dollars worth of silver. So far no one has found a profitable way to get these precious elements out of sea water. If all the minerals in the ocean were spread over the earth, they would make a blanket 150 feet deep. The amount of minerals in the ocean keeps increasing. There is about one tablespoon of salt and other minerals in a pint of sea water. This means there are now about 3 1/2 pounds of minerals in each hundred pounds of sea water.

Life in the Ocean

            The number of plants and animals on land is small compared to the number in the ocean. Some of the animals in the ocean are so small you cannot see them without a microscope. Some are the biggest on earth. They all must have food. Their food, just as for land animals, depends on green plants.
            The green plants of the ocean need light to make food, but, in other way, they are quite different from the plants that grow on land. Most of the plants of the ocean are very small. They are like those that sometimes get into a fish tank and make the surface of the water turn green.


            The small green plants of the ocean, together with small animals that feed on them, are called plankton. Plankton plants are the basic food of the sea. Each plant is very small. Thousands of them could fit on the head of a pin. Some plankton can move about in the water. All of them, however, are carried around by the movement of the water.
            Most of the plankton plants are diatoms. A diatom is a one-celled green plant without roots, stems, or flowers. Under a microscope the diatom cell looks like a little glass box made of two parts. These two parts fit neatly into one another. In between is the living part of the cell, which contains chlorophyll. There is a tiny slit in the glass-like box. Through this slit, the living part of the cell gets sea water. Sea water contains the carbon dioxide and minerals the cell needs to make food. It also contains the oxygen that all living things need. These plants do not need roots. They get materials directly from the water in which they float. These little plants usually grow above the ocean shelves because the water there contains more of the minerals they need. They can grow only as far down as light can reach about 400 feet. Diatoms do not reproduce by bearing seeds but more simply. Each diatom divides to form two. All one-celled plants and animals reproduce in this way. Diatoms can reproduce very rapidly. Under favorable conditions, diatoms may divide as often as 8 times in 24 hours. At this rate, you could begin with one diatom and have 256 the next day if they were all still alive. What happens to plant plankton affects the whole ocean. Without it, no life could exist in the sea. There are sea animals that eat other sea animals, that eat other sea animals. But always at the beginning of the food chain there is the green plant, the diatom of the sea. Even the microscopic animal plankton must get their food from these tiny, one-celled green plants.
Bread from the Sea
Plankton can be made into food for people. It can be pressed together and dried. The result is a paste that is very high in food values. It is 50% protein. It also contains fats, starches, minerals, and vitamins in fact, every nutrient people need. Its taste is mild, gritty, a little oily, and to some people it tastes like broccoli. Other people say it tastes like pumpkin. Noodles, soup, ice cream, and cookies can be made from plankton. And they taste good, too.
            Plankton plants grow not only in the ocean, but also in fresh-water lakes. They can be grown in tanks, too. All you need for a start is some of the plants, water, sunlight, and minerals.
            These plants could also be used for fuel. When dried, they burn with a slow, hot flame like coal. It was from living things like these that petroleum was formed millions of years ago. We also get oil for paints, and chemicals for medicines, from plankton.


            Seaweeds are many-celled plants that grow in the sea. Some of them grow to be very big. These plants are quite different from large land plants. Land plants need roots and stems to get water and minerals. Sea plants live in water. They absorb this water along with minerals through all their parts. Food can be made by all parts. Most seaweeds live at a depth of about ten to twenty feet. They are supported by the water so they do not need strong stems to hold them up. If seaweeds are out of the water, they sprawl all over the ground. They have nothing to support them. Seaweeds do not have roots, but they do have "holdfasts." These fasten to rocks or shells on the bottom of the sea. Seaweeds vary in color. Those which grow nearer the surface of the water are green. Farther down, seaweeds are brown and red. They have chlorophyll, but its color is hidden by the brown and red. This brown and red coloring helps them to use the smaller amount of light that reaches farther down into the water.
            The Japanese use a kind of seaweed called kelp to make into relishes, drinks, and even cake. In California, some kelps are sold as candy.
            If you ever felt seaweed just out of the water, you know it is slippery. A gelatin-like substance can be taken from it which is used by scientists for growing bacteria. It is also used in making jelly. Seaweeds are also rich in iodine.

Fish of the Sea

            Fish contain proteins, minerals, and vitamins. In all food values fish are equal to, and sometimes better than, other meat. Some fish and sea food taste very "fishy" and some can hardly be recognized by taste as fish or sea food. There are recipes for cooking fish to please almost every taste. When chefs prepare big banquets, one course in the dinner is usually a fish course. Carefully prepared fish can be delicious.
            Fish, with their rich mineral content, are one of the best fertilizers there is. Ground-up fish heads, scales, and bones are used as fertilizers today. Livestock and pets are sometimes fed ground-up fish. This provides valuable minerals and proteins which help animals grow. Cod-liver oil is rich in vitamin D. In the winter, when there is not much sunshine, cod-liver oil can provide this vitamin for your body.


            One way to increase our food supply from the ocean is to "farm" the ocean. There are underwater farms for oysters. Oysters live in the shallower, warmer waters of all oceans. They are often harvested wild by fishermen, but more and more they are grown in carefully prepared oyster beds. By special care, the oyster farmer can produce more and better oysters. Not all waters can be used for oyster farms. Some bays have become polluted. Oysters that grow in polluted water are not safe to eat.
            Oysters eat plankton, which is rich in iron and iodine. Therefore oysters are an excellent food for man. They are high in vitamins and in proteins.

The Great Mammal of the Sea

            In the nineteenth century, great sailing fleets roamed the Arctic and Antarctic oceans looking for whales. Men traveled far away from home, sometimes for three years, to hunt for whales for the oil as much as 15 tons of it from a single whale.
            Scientists say that whales were originally land animals. They have found fossils which show that whales once lived on land. Judging by the tremendous teeth and jaws of these fossils, scientists believe that land whales must have been powerful beasts. No one knows how whales became sea mammals. Perhaps generation by generation they moved farther and farther out into the sea to get food. Their bodies gradually became more suited to life in the water. Their hind legs became smaller and smaller. Today hind legs cannot be seen outside the whale at all. Their front legs changed into flippers for steering and balance. All these changes took place slowly over thousands and thousands of years.
            The whale is the largest animal on earth. One kind of whale, called the whalebone whale, eats plankton and shrimp. Since whales are mammals, they are not able to use oxygen from the water as fish do. Whales usually swim just beneath the surface of the water. Every few minutes the whales come to the surface to breathe. As a whale comes to the surface, it blows a tremendous spout of vapor from its nostrils, which are on the top of its head. In the air, the vapor condenses so that it can be seen. The spout is followed by a whistling rush of air into the nostrils. Then the whale disappears under the surface of the water again.
            The whale develops a layer of stringy white fat, called blubber, under its skin to protect it from cold water. In very cold water, this layer may be as much as 9 inches deep. Whales that live in warmer waters need less blubber. When the whale travels through warm water, some of its blubber may be used for energy because it is hard for it to find food in warm water. Whale oil is made mainly from the blubber.