Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Mrs. Evans: Light at the Bottom of the Deep Dark Ocean FOCUS QUESTIONS What colors, if any, are visible down in the deep sea? What is bioluminescence? LEARNING OBJECTIVES Students will learn that white light (visible light) is comprised of all colors of the spectrum. Students will learn that the quantity of light decreases with increasing depth in the ocean. Students will learn that the quality of light changes with increasing depth. Students will earn that red light penetrates water the least and that blue light penetrates water the most. Students will learn that many ocean organisms are bioluminescent. Students will learn that bioluminescent light is usually blue. Students will learn why organisms bioluminesce. Students will learn about several bioluminescent animals through independent research. Part I (Reading) Bioluminescence is simply light produced by a chemical reaction which originates in an organism. It can be expected anytime and in any region or depth in the sea. Its most common occurrence to the sailor is in the often brilliantly luminescent bow wave or wake of a surface ship. In these instances the causal organisms are almost always dinoflagellates, single-cell algae, often numbering many hundreds per liter. They are mechanically excited to produce light by the ship's passage or even by the movement of porpoises and smaller fish. Label and color the dinoflagellate to the right, blue. Next, under “startle” for Bioluminescent Reasons, add the critter dinoflagellate. On land it is most commonly seen as glowing fungus on wood (called foxfire), or in the few families of luminous insects. XC if you can tell me one: ___________. Like the squids and euphausiids (color blue), some bony fishes have special light producing structures called photophores. These structures are usually cup shaped and may have elaborate focusing lenses and reflectors to concentrate and direct the light produced by the photogenic cells. These photophores are generally controlled by nerves, and are supplied with blood vessels that deliver oxygen and energy sources needed for the light producing chemical reaction. Use a light blue to color the photophores on the next page (A), and yellow for the eye lens (H). The bars (A2) represent the bioluminescent glow. Color each fish as it is discussed in the text. Note that the bright flash (A2) of the caudal photophores of the lanternfish is represented as a burst of light. When coloring the flashlight fish, note that one is “blinking” and has its photophore (A3) covered by the skin fold (L). Many mid-water fishes utilize bioluminescence for purposes that are often not fully understood, due to the difficulties in studying these animals alive. The lanternfishes have photophores along their ventral surface (bottom). At night these fishes migrate to the upper layers of water where they feed on zooplankton. Seen from below, an unlighted fish would be clearly silhouetted against the moonlit water surface and thus be vulnerable to attack from below by predators using visual cues. Write in the lanternfish below (Reasons for Bioluminescence) after the appropriate explanation. Lanternfishes use their ventral photophores to erase this silhouette and blend with the moonlit upper waters. This phenomenon is known as counterlighting and occurs in a number of fishes, squids and crustaceans. The photophores of most squids can be turned on or off and their intensity varied by direct nervous control. Some deep sea squids that form schools probably use their bioluminescence to maintain contact with members of their species (possibly mating clues/write this species in the appropriate area for Reasons for Biolum). Color the firefly squid grey and the photophores (E) blue. Mating behavior in a pair of Green Lanternsharks (Etmopterus virens). Before mating, the male (in foreground) ritualistically bites the trailing edge of the female's pectoral fins ('love nips') in a tender gesture only sharks would understand. The pattern of photophores is species- and gender-specific, allowing Green Laternsharks to recognize others of their kind and to co-ordinate schooling and mating behaviors in the blackness of the deep-sea. The caudal (rear) photophores of many lanternfishes are used in evading predators. Seeing a threat, the fish emits a bright flash of light from the caudal photophores and, at the same time, swims rapidly away. The predator is startled and confused, and focuses its attention on the spot where the flash occurred giving the lanternfish an opportunity to escape. The hatchetfish uses its ventral photophores for protective counterlighting (write him in the appropriate spot for Reasons for Biolum. It also possesses unique upward facing eyes equipped with yellow lenses. The lenses serve as filters that allow the fish to distinguish the narrow color range of normal background light. By looking up into moonlit water, the hatchetfish can discern potential prey animals that are using photophores in counter lighting behavior, thus capitalizing on the defense mechanism of its prey. From our adaptations lecture, write what his eyes are called when they are “upward facing” next to the picture of the hatchetfish. The deep water predatory stomiatid attracts potential prey with a lure equipped with a photophore located on the fish’s chin whiskers; what is another name for these? Label it on the fish. Males are smaller and have a photophore beneath their eyes; the female is the only one that possesses this “whisker”. This photophore probably aids recognition between male and females in their dark environment. Write this in under Reasons for Biolum. The small (7-8cm) shallow water flashlight fish bears photophores that are among the brightest and largest found in any bioluminescent organism. However, the blue-green light emitted from these photophores is not produced by the fish themselves, but rather by billions of luminescent bacteria harbored within the photophore by the host fish. The fish’s blood stream keeps the microscopic inhabitants of this bacterial photophore supplied with nutrients and oxygen. The bacteria glow in a special pouch that is lined with dark skin arranged in such a fashion as to prevent the light from blinding the fish. As a control mechanism, the fish posses a fold of skin that can be raised over the pouch to cover the photophore and essential “turn off” the light. Flashlight fish remain hidden in the coral reef by day and on moonlit nights. On darks nights groups of from a few to sixty fish congregate near the surface. The combined glow of their bacterial photophores attracts their small zooplanktonic prey. If a larger potential predator is attracted to the light, the flashlight fish executes a strategic defense response known as “blink and run.” The fish swims in one direction with its light “on,” then covers the light and swims in a different direction (up to 75 times a minute). This effect of “blinking and running” is to confuse the predator and permit the escape of the small fish. Key Points -Bioluminescence is light produced by a chemical reaction which originates in an organism. -Bioluminescence is a primarily marine phenomenon. In contrast, bioluminescence is essentially absent in fresh water. -Bioluminescence has evolved many times in the sea as evidenced by the several distinct chemical mechanisms by which light is emitted and the large number of only distantly related taxonomic groups that have many bioluminescent members. -Bioluminescence is not the same as "fluorescence" or "phosphorescence". In fluorescence, energy from a source of light is absorbed and re-emitted as another photon. In bioluminescence or chemoluminescence the excitation energy is supplied by a chemical reaction rather than from a source of light. -At least two chemicals are required. The one which produces the light is generically called a "luciferin" and the one that drives or catalyzes the reaction is called a "luciferase." -Almost all marine bioluminescence is blue in color, for two related reasons. A notable exception to this "rule" is Malacosteid family of fishes (known as Loosejaws), which produce red light and are able to see this light when other organisms can not. Because it is found in so many different types of organisms, bioluminescence must serve many functions in the ocean. However many of the functions are still unknown, because experimental evidence has been gathered for only a few of the many proposed roles. Luminescence can serve two or more purposes, both offensive and defensive, within a single organism. Here we summarize the range of functions that have been proposed for marine bioluminescence. Light in the bottom of the Deep Dark Ocean (M&M Lab) Background Information: If you were able to combine all of the world’s ocean basins and stir them together with a spoon, the average temperature of the water would be 4°C, the average depth would be about 14,000 feet, and the average light level would be zero. The bulk of our oceans are comprised of deep sea habitats that exist in very little to no light. With regard to light level, the ocean has been divided into three zones based on depth and light level. The specific depths of these zones will vary based on a number of physical parameters, but the following three divisions can be used when talking about light levels in ocean waters. The upper 200 meters of the ocean is termed the photic zone. This zone is penetrated by sunlight and plants thrive. The zone between 200 meters and 1000 meters is known as the “twilight” zone; in this zone the intensity of light dissipates as depth increases and at the lower depths, light penetration becomes minimal. The aphotic zone, or “midnight” zone, exists in depths below 1000 meters. Sunlight does not penetrate to these depths and the zone is bathed in darkness. Since a bulk of the ocean contains vast regions where light levels are low to nonexistent, numerous species that inhabit these deeper waters produce their own light. This biological process is termed what:______________________. As you travel from surface waters to deeper waters, the quantity of light changes; it decreases with depth. The quality of light also varies with depth. Sunlight contains all of the colors of the visible spectrum (red, orange, yellow, green, blue and violet). These colors combined together appear white. Red light has the longest wavelength and therefore the least amount of energy in the visible spectrum. Violet light has the shortest wavelength and therefore the highest amount of energy in the visible spectrum. The wavelength decreases and the energy increases as you move from red to violet light across the spectrum in the following order: red, orange, yellow, green, blue and violet. Red light is quickly filtered from water as depth increases. As the wavelength of light increases from red light to blue light, so does its ability to penetrate water; blue light penetrates best. Green light is second, yellow light is third followed by orange light and red light. The exception to the rule is violet light. Although it has the shortest wavelength and the highest energy, violet light is also quickly filtered from water; the small wavelength of light is easily scatted by particles in the water. All objects that are not transparent or translucent either absorb or reflect nearly all of the light that strikes them. When struck by white light (containing all colors), a red fish reflects red light and absorbs all other colors. Likewise, grass reflects green light and absorbs all other colors. White objects appear white because they reflect all colors of light in the visible spectrum. Black objects appear black because they absorb all colors of light. Now consider that red fish. If a red fish is swimming at the surface of the ocean, it appears red because it reflects red light. Can you see a red fish swimming at 100 meters? At this depth the red fish is difficult, if not impossible to see, and appears blackish because there is no red light to reflect at that depth and the fish absorbs all other wavelengths of color. In the twilight zone, there are numerous animals that are black or red. At depth, these organisms are not visible. The black animals absorb all colors of light available and the red animals appear black as well; there is no red light to reflect and their bodies absorb all other available wavelengths of light. Thus red and black animals predominate. Since the color blue penetrates best in water, there simply are not that many blue animals in the midwater regions of the ocean; their entire bodies would reflect the blue light and they would be highly visible to predators. Animals that seek to produce something visible to other organisms have taken advantage of the penetration of blue light in water. Many ocean animals, especially those living in the twilight and midnight zones, are bioluminescent and can produce their own light. Most bioluminescence, although not all, produces blue light. This now makes sense. An animal producing red light in deep water would produce light that is not visible. Blue light, in the form of bioluminescence, is visible at depth. Bioluminescence has evolved in many different species and this suggests its importance to survival in the deep sea. Prelab questions: 1. What is the average temperature of the ocean? 2. Describe the three ocean “zones.” 3. Why is red light quickly filtered from water as depth increases? 4. What two colors penetrate water best? 5. Why does a red fish “appear” red when struck by white light? 6. Why does a black fish “appear” black and a white fish “appear” 7. Why is it advantageous for deep sea fish to be black or red? 8. Why are there not that many blue animals in the “twilight zone” of the ocean? 9. Why would some deep sea creatures emit a red light? Light in the bottom of the Deep Dark Ocean 1. Get out one piece of black construction paper, one set of Deep Sea Diving Goggles, and one “M&M set” for each pair. (The black piece of paper represents the darkness of the deep sea.) 2. Spread your M&Ms out over the black piece of paper. 3. Place one of the 3 layers of blue report covers over your eyes and while looking through the blue layer, observe which colors of M&Ms are readily visible. ___________________________________________Each lab partner needs to observe this. 4. Add an additional report cover layer (total of two layers) and repeat your observations. __________________________________________________ 5. Add your last layer. _________________________________________ Note: Using the blue report covers allows you to see how colors appear in deeper water. The blue covers filter out other colors of the spectrum with increasing efficiency as additional layers are used. Water, likewise, with increasing depth selectively filters out all other colors of the spectrum with the exception of blue. Did you observe that the color black disappears first, followed by red, then orange, and yellow? _yes/no__ 6. Why again are there are so many red animals living in the twilight zone? __________________________________________________________________________ __________________________________________________________________________ 7. Why do you think most bioluminescence produces blue light and not some other color? __________________________________________________________________________ __________________________________________________________________________ Part III Chemiluminescence This reaction involves two basic ingredients, an oxidizing agent (hydrogen peroxide), and the reactant solution (luminol). When the hydrogen peroxide is mixed with the luminol solution, the electrons get excited, producing photons of light. Even heat, which is generally associated with the light of most kinds, is noticeably absent. Light sticks, which all of us are familiar with contain chemicals in two compartments separated by a divider. When the divider is broken and the chemicals mix, chemiluminescence results. The greater the rate of reaction, the greater the amount of light produced. Mrs. Garbiel (or her TA’s) has already done this procedure but FYI: 1. Empty one vial of reagent A (Luminol) in a beaker and thoroughly dissolve it in 500 mL of tap water. This should be prepared shorlty before use as Luminol begins to deteriorate when in solution. 2. In another beaker, measure 30 mL using a graduated cylinder of the stock Luminol Activator solution and dilute it with 470 mL of water to make 500 mL. This is where YOU begin. 3. Measure 5 or 10 mL (Please circle which one Mrs. Garbiel said to use) of each of the above two solutions into two clean flasks, graduated cylinders or test tubes. 4. Darken the room as much as possible. 5. Pour the two solutions simultaneously through a funnel into your tube. 6. As the two chemicals interact, light is released. What was the color of the solutions before the reaction? ______________ What was the color of the solutions after the reaction? _______________ Part IV Your own Glowsticks. Write down Mrs. Evans’s procedure: Part V OPTION 1: Research another bioluminescent organism and write a 1 page report or create a poster describing its habitat, behavior and mechanism of bioluminescence. Some examples: Anglerfish Bristlemouth Fangtooth Filetail catshark Snailfish Midwater shrimp Sixgill shark Giant ostracod Giant red mysid Gulper eel Hatchetfish Lanternfish Eelpout Blackdragon Hagfish Viperfish Shining tubeshoulder Snipe eel Ratfish Squat lobster Mrs. Garbiel: Marine Biology Spring 2010