Week 30 - Aquatic Organisms are Affected by Many Factors

Lesson 8

Lesson 8: Adaptations
Read pages 372 - 380

To this point in the unit, you have studied the distribution and importance of water on Earth. You have also been introduced to freshwater and saltwater ecosystems. In this lesson, you will learn more about the plants and animals that are adapted to survive in the freshwater and saltwater ecosystems. You will begin with an introduction to structural and behavioral adaptations of organisms. All organisms have certain adaptations that allow them to survive in some areas and not in others. For example, a whale stranded in shallow water or on a beach does not survive very long even though whales are air-breathing animals. An adaptation is any structure or behavior that helps an organism survive in its environment. Adaptations develop in a population over a long period of time.

Structural Adaptations

Some organisms have body structures that help them survive in their habitat or environment. The blubber in seals and whales helps protect these mammals from the cold temperatures in northern ocean waters.

Fish and many other aquatic animals use gills to extract oxygen from the water.
Many aquatic plants and algae have devices that allow them to float on the surface of water to make sure they get the light they need for photosynthesis.
Bull kelp with hollow ball that helps it to float on the surface.

Caddisfly larvae in nest
Insect larvae that live in fast moving streams are usually flat or form homes of rocks and twigs to prevent being washed away.

Behavioral Adaptations

Some organisms display behavioral adaptations that help them survive in their habitat.

For example, salmon spawn in freshwater streams and then migrate to the ocean to feed and grow.
Many types of fish gather together in large numbers to protect them from predators.
Intertidal organisms such as sea stars crawl under rocks and in crevices to keep out of the sun when the tide goes out.
The diagram in the text on pages 376-377 is misleading. It appears to be showing that the different zones are horizontal but the following pictrures show how the zones are related to the zones depth not a horizontal layer.
The pictures below show that depth is how the zones are selected. There are 4 titles for the zones used in the text. These ate the titles you need to remember.
Intertidal Zone
Continental Shelf Zone
Oceanic Zone

Exercise 3.1A: Adaptations

Exercise 3.1B: Aquatic Diversity

Enrichment Opportunities
1. For more information on saltwater ecosystems, go to the Nature Web Marine Communities web site. Here you will find information on the different marine ecosystems and the plants and animals that live in this area. 2. For more information on freshwater ecosystems, go to the Nature Web Freshwater Communities web site. Here you will find information on the different freshwater ecosystems and the plants and animals that live in this area.
( http://www.nhptv.org/natureworks/nwep7.htm )

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