Humpback whales near the Hawaiian Islands
Click on image for full size
Courtesy of NOAA
Life in the Open Ocean
The open ocean, called the pelagic zone, is the largest area of the marine ecosystem. It reaches from coasts to the middle of the ocean. The living things that survive in the open ocean need to have a way to float or swim in ocean water.
The area of the open ocean where sunlight shines through the water is called the photic zone. Most life in the open ocean is found in the photic zone.
Animals, protists, plants, and bacteria that float or drift in ocean water are called plankton. They are moved around the open ocean by surface currents and wind. Phytoplankton are types of plankton that do photosynthesis like diatoms and other algae. They are the beginning of food chains. Zooplankton are animals and one-celled protozoa that drift in the ocean water. Many zooplankton eat phytoplankton. Some zooplankton eat other types of zooplankton.
In the open ocean there are many types of swimmers including fish, whales, and sharks. Some fish, such as herring and tuna, swim in schools while others swim alone. Some animals have other ways of moving besides swimming. For example, squid propel themselves through the ocean with a jet of water and flying fish are able to glide just above the water surface using fins shaped like wings.
In the parts of the open ocean below where light can penetrate, there are fish and other animals like giant squid. Because there is no sunlight, there are no algae to start food chains. Instead many animals living in the deep ocean rely on the bodies of dead animals falling from the water above for food.
Last modified June 1, 2010 by Lisa Gardiner.
Shop Windows to the Universe Science Store!
The Summer 2010 issue of The Earth Scientist
, available in our online store
, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.
You might also be interested in:
Members of the Kingdom Protista are the simplest of the eukaryotes. Protists are an unusual group of organisms that were put together because they don't really seem to belong to any other group. Some protists...more
Photosynthesis is the name of the process by which autotrophs (self-feeders) convert water, carbon dioxide, and solar energy into sugars and oxygen. It is a complex chemical process by which plants and...more
The deep ocean is very cold, under high pressure, and always dark because sunlight can not get down that far. Less life can survive in the deep ocean than in other parts of the ocean because of these conditions. ...more
An aquifer is the name for a layer of rock which is capable of holding a large amount of water. Some layers are better at holding water than others, for example a layer of sandstone can hold a good deal...more
Carbonate is a name for rocks and minerals which contain a molecule made of both carbon and oxygen known as CO32-. (CO32- is also known as the molecule carbonate). Limestone is an example of a calcium...more
The deep ocean waters are under pressure and are much colder than layers of the ocean which are closer to the surface. Dissolved carbon dioxide seems to be absent from the deep ocean water and as a result...more
One process which transfers water from the ground back to the atmosphere is evaporation. Evaporation is when water passes from a liquid phase to a gas phase. Rates of evaporation of water depend on things...more