The Ocean is Earth’s largest reservoir of fresh water and a vital part of the planet’s ecosystem. A healthy ocean regulates climate and reduces impacts of global warming. It also provides billions of people with food, including fish and other seafood.
The world’s oceans cover about 71% of the surface of our planet. They contain over one billion cubic kilometers (about 620 million square miles) of water, about half the total amount of water on the planet.
There are more than 71,000 species of living things on Earth, but most animals and plants that live in the ocean are small or invertebrates. Animals include eels, crabs and clams; plant-like creatures called sea anemones, corals and sponges; and the largest marine mammals on Earth: blue whales.
Animals are found on all levels of the ocean, from the deepest trenches to shallow waters. They have evolved to adapt to their environment.
Many different kinds of animals can be found in the ocean, from squid to dolphins to whales and sharks. The largest of these is the blue whale, which weighs more than 50 tons and can be more than 100 feet long.
Most of the creatures that live in the ocean have a backbone, but there are some that don’t. For example, jellyfish and shrimp don’t have a backbone and move using their tentacles.
Oceans are the world’s most important source of energy and nutrients. They provide at least a fifth of the animal protein that we eat. They play an important role in the world’s economy, generating nearly US $3 trillion annually.
The ocean regulates weather and temperature, absorbing heat and carbon dioxide from the atmosphere and preventing abrupt changes in climate. It absorbs about a quarter of the excess CO2 produced by burning coal, oil and gas.
A moderate temperature is an essential condition for life in the oceans and on land. Without oceans, temperatures would fluctuate dramatically over much of the world.
Warm water from the equator and cold water from the poles mix together, making the temperature moderate. This helps to prevent sudden temperature changes that can damage marine life and crops.
Some of the smallest organisms on Earth can be found in the ocean, such as tiny plants called phytoplankton that produce an estimated 50-80% of the oxygen on Earth. The smallest animals are also found in the ocean, such as zooplankton.
Scientists are discovering new and fascinating ways to explore the depths of the ocean. Marcello Calisti, an explorer in residence at National Geographic Society, is working on an underwater robotics project that uses legged locomotion inspired by the way an octopus moves under the water.
The world’s oceans contain some of the most nutrient-rich waters on Earth. They support an estimated 80% of the marine life on the planet, and they provide a major source of fish and crustacea for human consumption.
Most of the phosphorus, calcium and potassium that make up our bodies come from the oceans. We need these minerals to build proteins and enzymes in our cells, which help us stay healthy and active.