effect on other species. This may cause the entire ecosystem to collapse. Coral reefs are
particularly sensitive to certain threats like temperature change and oil spills.
The open ocean refers to the large open expanses of ocean water. This vast area is the
primary habitat for relatively few animals. Most of the food in the ocean is found nearer to
shore, so most of these animals are just passing through. Some larger animals like whales
and giant groupers may live their entire lives in the open water.
As you know, scientists were surprised to find life in ocean trenches, the deepest parts of
the ocean. How can animals survive at that depth? They have adapted to the resources
available there, and some bacteria can even use inorganic compounds as energy sources
instead of relying on the sun as a source of energy. This is calledchemosynthesis. Shrimp,
clams, fish, and giant tube worms have been found in these extreme places.
Still other animals can live on floating rafts of algae or in frozen places, like the North
and South Poles. No matter where you might look in the grand ocean, some creature has
found a way to live there. Almost all of these creatures depend on each other. Certainly all
creatures depend on producers that convert sunlight into biomass. Our oceans are currently
threatened by global warming, overuse and pollution. These imbalances in the ecosystems
may someday devastate the delicate web of life on which humans depend.
Lesson Summaries
- Our oceans are home to a tremendous diversity of life including the very smallest
bacteria to the very largest baleen whale. - Some marine organisms float at the surface using the sun’s energy, some exist at great
ocean depths transforming chemicals in the water into food. - Plankton are freely floating organisms that include the photosynthetic phytoplankton
as well as the animals that eat them, the zooplankton. - Virtually every phyla on Earth is represented in the ocean including invertebrate and
vertebrate organisms, fish, reptiles, seabirds and even air breathing mammals. - Manycreaturesintheoceanliveincooperationwithotherorganisms, likecoralanimals
that live symbiotically with dinoflagellates in their tissues.
Review Questions
- What are seven categories of life in the ocean?
- What does “invertebrate” mean?
- What is the group of organisms are the primary producers in the ocean, on which all
other life depends? - If fish require oxygen to live, why can’t they survive on land?
- Some people argue that polar bears are not really marine mammals because they don’t
live in the ocean itself. They would say polar bears are land animals like all other