Ocean Habitats 5-2 Notes

Ocean Habitats: Ocean Zones and Conditions Ocean zones include the intertidal zone, the neritic zone, and the open-ocean zone. ● At the highest high-tide line on land, the intertidal zone begins. ● The neritic zone extends from the low-tide line out to the edge of the continental shelf. ● Beyond the edge of the continental shelf lies the open-ocean zone. This zone includes the deepest, darkest part of the ocean Life in the Ocean ● The ocean is inhabited by organisms at every depth. ● Scientists classify marine organisms according to where they live and how they move. ● Plankton is tiny algae and animals that float in the water and are carried by waves and currents. Algae plankton include geometrically shaped diatoms. Animal plankton include microscopic crustaceans and some tiny young fish. ● Nekton are free-swimming animals that can move throughout the water column. Squid, most fishes, and marine mammals such as whales and seals are nekton. ● Benthos are organisms that inhabit the ocean floor. Some benthos, like crabs, sea stars, octopus, and lobsters, move from place to place. Others, like sponges and sea anemones, stay in one location. Relationships Among Organisms: ● Plankton, nekton, and benthos are all found in most marine habitats. ● Many plankton and benthos are algae. ● Like plants, algae use sunlight to produce their own food through photosynthesis. Photosynthetic plankton are called producers. ● Other plankton and benthos, as well as all nekton, eat either algae or other organisms. They are called consumers. ● Finally, some organisms, including many benthos, break down wastes and the remains of other organisms. They are called decomposers. Ocean Food Webs: ● All of the feeding relationships that exist in a habitat make up a food web. ● Each organism in this Arctic food web depends either directly or indirectly on the algae plankton. ● Throughout the ocean, plankton are a source of food for other organisms of all sizes. Review Questions: 1. Identify the three ocean zones. - Intertidal zone, neritic zone, open-ocean zone. 2. What characteristics do scientists use to classify ocean organisms? - According to where they live and how they move. 3. Identify the three categories of ocean organisms and describe their characteristics. - Plankton: algae plankton and animal plankton, many are microscopic organisms - Nekton: free-swimming animals such as fish and marine animals - Benthos: bottom-dwellers that slowly move from place to place or stay in one place 4. Sea cucumbers are small animals that crawl along the ocean floor. To which category of ocean organisms do they belong and why? - They are benthos because they inhabit the ocean floor.