Species Live in the Ocean

 

How Many Species Live in the Ocean?

The number of species that live in the ocean is unknown.

Given the vast size of the ocean, it is impossible to know the exact number of species that live there. Research suggests, however, that the number of species in the ocean is decreasing. The continued decline in the health of many ecosystems, coupled with rising extinction rates, are likely outpacing species’ ability to evolve to tolerate the conditions of our rapidly changing planet. It is not all bad news, though. Researchers around the world continue to study marine life and habitats to help develop new strategies to preserve vital ocean ecosystems.

Scientists estimate that 91 percent of ocean species have yet to be classified, and that more than eighty percent of our ocean is unmapped, unobserved, and unexplored.. While these statistics may sound daunting, they have not stopped the global scientific community from striving to amass as much knowledge as possible about ocean life.One recent effort—the Census of Marine Life—was an international project spanning 10 years that recorded the diversity, distribution, and abundance of life in the ocean. More than 2,700 scientists from 80 nations contributed to the Census. The results of their research, which included 540 marine expeditions, were reported at The Royal Society of London in October 2010. The Ocean Biogeographic Information System contains the Census data. NOAA Fisheries is responsible for the protection, conservation, and recovery of endangered and threatened marine and estuarine species in the United States under the Endangered Species Act.

Ocean Habitat

From outer space Earth looks like an awesome blue marble. That’s because most of Earth’s surface—more than 70 percent—is covered by oceans.

Oceans are areas of salty water that fill enormous basins on the Earth’s surface. Even though Earth has one continuous body of saltwater, scientists and geographers divide it into five different sections. From biggest to smallest, they are the Pacific, the Atlantic, the Indian, the Antarctic (sometimes called the Southern), and the Arctic Oceans.

Oceans are deep as well as wide. On average an ocean is a little over two miles deep. But about 200 miles southwest of Guam in the Pacific Ocean, the water in the Mariana Trench is almost seven miles deep. That’s the deepest part of the ocean.

Ocean Life

Scientists estimate that about one million species of animals live in the ocean. But most of them—95 percent—are invertebrates, animals that don’t have a backbone, such as jellyfish and shrimp. The most common vertebrate (an animal with a backbone) on Earth is the bristlemouth, a tiny ocean fish that glows in the dark and has needle like fangs.

Some of the smallest animals on Earth can be found in the ocean. Sea animals like zooplankton are so small you can see them only with a microscope. Big fish swim through these waters too, such as great white sharks, manta rays, and ocean sunfish.

The largest animal ever to live on Earth is an ocean mammal called the blue whale. It’s as long as two school buses! Dolphins, porpoises, and sea lions are also ocean-dwelling mammals.

The ocean teems with plant life. Most are tiny algae called phytoplankton—and these microscopic plants have a big job. Through photosynthesis, they produce about half of the oxygen that humans and other land-dwelling creatures breathe. Bigger algae like seaweed and kelp also grow in the ocean and provide food and shelter for marine animals.

Watery Habitats

Temperature, ocean depth, and distance from the shore determine the types of plants and animals living in an area of the ocean. These regions are called habitats.

Coral reefs are one type of habitat. When tiny animals called polyps die, their skeletons harden so other polyps can live on top of them. Then those polyps die, and more move in. After thousands of years, this becomes a complex structure called a coral reef that provides food and shelter for many kinds of ocean animals. In fact, corals reefs have been called the rainforests of the sea because of the wide variety of animals found there. Animals such as seahorses, clownfish, and sea turtles all live on coral reefs. And corals themselves are animals! They grab food from the water using tiny tentacle-like arms.

Kelp forests found along the coastlines of the Pacific and Antarctic Oceans also provide food and shelter for marine life. These large, brown, rubbery plants have hollow, globe-shaped growths on the leaves called pneumatocysts that help the plants rise to the surface. Sea lions, whales, shore birds, and other ocean animals make meals of the smaller critters that hide in the leaves.

Other ocean habitats aren’t actually in the ocean, such as estuaries. Estuaries are areas where rivers and oceans meet and have a mix of saltwater and freshwater. Oysters, crabs, and many birds like great herons and egrets live in estuaries.

Scientists estimate that we’ve only explored 5 percent of the ocean. Maybe you’ll be the next person to discover a new species of fish or a deeper underwater trench!