Life In The Sea

[Music] this is the sea in which many millions of years ago all life on Earth is believed to have started at the surface of the sea which covers more than two-thirds of the Earth's area there is little life to be seen but beneath the surface there are great communities of living things a motion picture camera built for underwater photography makes it possible for us to see some of this life under the ocean the salt waters of the sea are the home of billions of tiny creatures both plants and animals here too are the largest of the animals quills as well as some of the biggest plants like this floating submarine grove of kelp found along the California coast life in the sea can be divided into three main groups the first of these consists of tiny forms of life so small that they cannot be seen with the naked eye through the microscope we can see the wealth of life that floats and drifts with the movement of the ocean waters this microscopic ocean life is called plankton it consists of both tiny plants and tiny animals members of the plankton group far outnumber other kinds of sea life a second group of sea life includes all those forms which live upon the bottom of the ocean usually they are found in the shallow portions of the ocean floor but some are found at the greatest depths the bottom-dwellers includes such animals as mussels barnacles sponges grab and lobsters these forms of life have little or no capacity for swimming they find their food on the ocean floor the third main group of sea life includes all those animals we usually think of as fish and all others which are free to roam wherever they will in the ocean in addition to fish these include sea turtles and mammals that live in the sea like sea lions and many others it is obvious that these forms of life that are able to move about freely on their own power searching for food and running from enemies have a distinct advantage over the bottom dwellers and the plankton just as life on land could not continue without the oxygen in the air so all forms of life under the sea depend on the oxygen that is contained in the ocean waters not as bubbles but dissolved in the water the fish is equipped with gills which serve it much the same way that lungs serve land animals the fish takes in water through its mouth closes its throat and passes the water through its gills the gills extract the oxygen from the water and pass it directly to the bloodstream of the fish life under the sea also depends on the heat and light from the Sun for its energy just as does life on the land in the sunlit upper layer of the sea is found the chief pasturage the basic food of the oceans this food billions of tiny plants and animals takes its life from the chemicals in the ocean water as well as from the heat and light of the Sun also included in plankton are the young of crabs lobsters worms and clams these in turn become the food of the fish like the mackerel herring or sardine the smaller fish become the food of the larger ones and so on up the scale of life in the oceans even the huge whale is sometimes attacked and eaten by other whales as on land the search for food is a primary occupation of the creatures of the sea and all forms of life serve other forms as food not only do the various species thus keep alive but the various populations are at the same time controlled this then is the economy of the sea for every large animal there are greater numbers of small ones the diatoms outnumber the copepods the copepods outnumber the small fish the small fish outnumber the larger ones this relationship is often called a pyramid of numbers because of this ever-present danger of being used as food the creatures of the sea have numerous ways of meeting the problem of survival this lobster hides in a rock fissure several animals may fight for possession of this crack in the rock this hermit crab tries to protect himself and stay alive by hiding in a seashell some escaped destruction if only temporarily by speed of retreat others are protected by camouflage like this angel shark which can cover itself with sand or like this abalone whose shell is covered with plant stems and other growth the octopus can change color to make itself less conspicuous and if ever in danger can emit an inky smokescreen other forms of protection are the spines of the puffer fish the sting of the jellyfish the armor of the lobster the camouflaged shell of the abalone and the poisonous stinger of the Ray some fish gain protection by attaching themselves to larger animals others depend on mere sight to protect them from enemies but no individual or species is free from the danger of being eaten by others the only sure method of survival is through reproduction the larger seat creatures such as the flail which are better able to protect themselves give birth to only one or a few young ones at a time while the lobster carries under its tail a cluster of eggs which numbers in the thousands some sea creatures release their eggs to float freely in the ocean and hatch where or when they can many of these eggs are destroyed before they have a chance to hatch with some species perhaps only one out of 1 million eggs will reach maturity the octopus like a mother hen sits on its egg most of the very smallest forms of ocean life reproduce very rapidly to make four and four make eight until soon the new generations may number in the billions at times reproduction is so abundant that the surface may become discolored with these microscopic forms such a plankton bloom as it is called may cover many square miles and become poisonous to fish and other animals this is known as a red tide the riches of the sea have served not only its own denizens since the beginning of time but also the dwellers on the land birds like the seagull and the Gila Mott find their food in the ocean and man himself benefits from the treasures of the sea his diet in all parts of the world has always included the products of the ocean tuna mackerel swordfish abalone crab lobster clam and many more the economy of man has also been enriched by other uses of the products of the sea pearls mother-of-pearl ambergris from the sperm whale for perfume leather from the shark skin for shoes and purses jewelry from shells as well as valuable medicines and agar from kelp thus the abundant life of the see carefully harvested adds to the abundance of man's life on the land [Music]