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Do-It-Yourself Summary
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Read each sentence and identify the word/phrase that you believe correctly completes the statement. Then, click on the arrow to see if your answer is correct.


1. The waters below the photic zone can be divided into the zone and the deep sea. The deep sea often is divided into the , , and (or ) zones. The distinction between the mesopelagic and deep sea is based on the penetration of , whereas the division of the deep sea into different zones is due mainly to and/or , and the availability of food.

2. As ocean depth increases, both the amount of food and the abundance of life .

3. Most midwater fishes have adapted to the lack of food by developing mouths and jaws equipped with formidable teeth. They also have very (or ) feeding habits.

4. Midwater fishes that make vertical migrations differ from non-migrators in the degree of development of their , bones, and .

5. Sensory adaptations in midwater animals include and, in fishes, a well-developed , which may explain the long bodies of many fishes.

6. The refers to the concentration of vertically migrating midwater animals that show up on sonar. It consists mainly of , , and .

7. refers to the use of bioluminescence to mask the silhouette. Other possible uses of bioluminescence include , , and .

8. The oxygen minimum layer results from in the mesopelagic.

9. Physical characteristics of the deep sea include a lack of light, constant salinity, low , and great .

10. The most common deep-sea pelagic fishes are and .

11. Common adaptations in the deep pelagic realm include size, mouths, stomachs, coloration, muscles, and the lack of a

12. Solutions to the problem of finding mates in the deep sea include the use of and as signals, , and , in which the male attaches to the female.

13. The two main factors that probably control the depth ranges of deep-sea organisms are and .

14. feeding is the main mode of feeding in the deep-sea benthos.

15. Deep-sea hydrothermal vents support rich biological communities. The primary producers in these communities are not plants but bacteria that use instead of light to produce organic matter.







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