f98u3le2 - Lesson II: Animal Adaptations and Distributions...

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Lesson II: Animal Adaptations and Distributions I Key words: Photosynthesis, topography, phytoplankton, nutrients, phytoplankton blooms, buoyant, cilia, fusiform, lunate, caudal peduncle, deep scattering layer, diel migrations, euphotic, metabolism, pupil, rods, cones, retina, photophores, ventral, microhabitat, food-poor, opportunistic, gill rakers During this program we will discuss organisms of the epipelagic and mesopelagic zones focusing on the adaptations that allow them to live in these environments. Included in this show will be the vertical migrators. Organisms of the Epipelagic Zone The Epipelagic zone is the uppermost layer of the ocean; it is located between the surface and 600 feet in depth. It is in this thin layer that all photosynthesis takes place. The epipelagic zone only represents 2-3% of the entire ocean, beyond this, light is too dim for photosynthesis to occur. In fact, in all the world’s oceans, 65% of the plankton are in the top 500 meters. Not all surface waters are productive and much is featureless. Therefore in the surface waters, temperature, light, topography, and distance from land tend to determine organism distribution. Phytoplankton need nutrients (fertilizer) in addition to lots of sunlight. Much of the open ocean is nutrient poor and there is little phytoplankton growth. Areas close to land tend to have higher nutrient content because of runoff from land. These areas with higher nutrients have phytoplankton blooms. Zooplankton , (small animals that float with the currents that we think of as fish food) feed on phytoplankton and are present in higher numbers where blooms occur. In the well-lit epipelagic-zone, most predators use vision to seek out prey. There are several adaptations that allow prey organisms to survive here. One adaptation is small size. The most numerous organisms of the sunlit zone, the zooplankton, are small. When you are small, not only are you hard to see, but it is easier it is to stay afloat. If an organism is small and light it can stay up in the water column longer. Larger gelatinous organisms, like jelly- fish are also very hard to see because they are transparent and they have a density close to that of water; this allows them to be both hard to see and neutrally buoyant.
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cilia, tiny hairs on their body, this increases their resistance to sinking, and can also be used for locomotion, touch, or to sense water movement. A diatom A comb jelly Most epipelagic fishes have streamlined or fusiform bodies (spindled-shaped like a submarine), that allow them to slide through the water more easily, which is important if you are swimming continuously. Many have adaptations that help them swim fast such as a lunate tail or a narrow caudal peduncle . They also have a lot of muscle mass, which enables them to be strong swimmers. Good examples of these adaptations can be seen in a tuna fish, shown below. This picture also shows water flow over the fusiform shape. terminal
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This note was uploaded on 07/31/2011 for the course OCB 6050 taught by Professor Staff during the Spring '11 term at University of South Florida - Tampa.

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f98u3le2 - Lesson II: Animal Adaptations and Distributions...

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