Elements of The Oceans:

General Information About Ocean Marine Life:


Many animals live in and under the water, and many people believe life began in the ocean. Sea life thrives in water on the continental shelf. Fish swim in the water while other organisms creep around or burrow into the ocean floor. Coral attaches itself to the ocean floor.

Seaweed and other plants need sunlight for growth. Sunlight only reaches about 100 meters into the water; therefore most of the ocean's plants thrive on the continental shelf.

Sea organisms that are free swimming can live at all levels in the ocean. Various factors such as sunlight, salt variations, currents, and available nutrients affect their movements. Rivers carry sediment-containing nutrients into the oceans. Organisms also get nutrients from plants, other organisms (food chain), or remains of organisms.

Much of marine life is dependent upon microscopic plankton as a source of food. Phytoplankton is the plant form of plankton and zooplankton is the animal form. Both types require sunlight to live and are found in shallow surface waters of the ocean. Sea organisms of all sizes depend on plankton as a source of food, even whales.

The colder water near the ocean bottom is also rich in nutrients. When organisms die in shallow water, their remains sink slowly to the bottom. Fish eat the remains as they sink, and anything left over falls to the ocean floor. Experienced fishers search for rising, cold currents, knowing fish can be found as these nutrients are swept up from the ocean floor.

It has also been discovered that organisms do survive in the deepest parts of the ocean, where there is not sunlight. Some fish are luminous. By making their own light, they can communicate; attract mates, hunt, and scare away or fool predators.

Near hot water vents, giant tubeworms and albino shrimp thrive on microscopic bacteria. The bacterium gets its nutrients from the minerals released in the hot water vents.

Therefore, life can be found in all levels and areas of the ocean.

Habitat Adaptations:

Aquatic animals are the product of countless adaptations over long periods of time. These adaptations, for the most part, are features that increase the animals' likelihood of surviving in their habitat.

What do fish have that makes it easy for them to live underwater? Gills are necessary if the fish are to breathe oxygen through the water. Scales protect them and make water flow around their bodies. Many fish also have swim bladders. A swim bladder is basically a balloon that fish can inflate and deflate. It helps them to go down deeper in water (deflate) and come back up (inflated). It also helps them adjust to changes in water pressure.

Color is very important. Camouflage coloration helps animals blend in with their surrounds. The octopus changes color instantly from black to gray to red to match its background. Spots and strips, disruptive coloration, breaks up the body shape of some fishes and conceal them against their backgrounds. False eye spots or unusual color patterns may hide vulnerable parts of an animal's body. Coloration can also advertise a service or act as a warning against predators. Counter shading is when ocean animals have dark backs and light bellies. Viewed from above, dark backs blend with the dark backs blend with the darkness of the deep ocean. From below, it is difficult for predators to see light bellies against bright sunlight surface waters.

Body shape gives important clues about where fish live and how they move. Powerful tails help fish chase prey and avoid predators. The elongated, arrow-like fish are hunters and ambush their prey. They float motionless until a smaller fish swim near. Then lunge out with lighting speed to seize their victim. The flat fish use shape as camouflage instead of speed for survival. The puffers or balloon fish their bodies with air becoming too big to be swallowed. Snake-like fish are slow swimmers but move easily through cracks and crevices, under rocks and around aquatic plants. Fish flatted from side to side are able to make quick sharp turns and dart in and out of hiding places.

Many animals combine behavior and special body features to insure their survival. Bioluminescence fish are built in light systems used to signal other fish, confuse predators and locate food. Barbells are whiskers used for feeling and tasting, especially in murky water. The shape of the mouth plays a role. For example, the long slender snout of he long-nose butterfly fish allows it to feed on tiny invertebrates that hide in the cracks and crevices of the coral reef. Several fish have special body organs that produce electricity for protection. Other animals have sharp or poisonous spines for protection. All of the adaptations make survival easier.

Additional Resources On Ocean Marine Life:

Ocean Marine Life Movie:

Ocean Marine Life Movie Quiz:

Downloadable Student Activities:

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