DEEP SEA. Over the past decade, much has been learned about the. Adapting to the A FUN ACTIVITY WITH BIOLUMINESCENCE

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1 Adapting to the DEEP SEA A FUN ACTIVITY WITH BIOLUMINESCENCE by Gwynne Rife Over the past decade, much has been learned about the ocean s secrets and especially about the creatures of the deep sea. The deepest parts of the oceans are currently the focus of many new discoveries in both the physical and biological sciences. From the abyssal plains to the animal communities around the hydrothermal vents, our knowledge is rapidly increasing. Middle school students find the deep sea fascinating and especially seem to enjoy its mysterious and spooky side. Bringing the deep sea to a landlocked classroom has produced some of my most memorable moments, and this activity has never failed to motivate and interest middle level students. Launching the study Giving students a feel for the physical parts of the deep sea should include a brief explanation of why the hydrostatic (water) pressure can be as much as 16,000 pounds per square inch, how it is cold and stable, and especially an understanding that no visible light reaches to this depth. Additionally, background information should cover deep-sea smokers, also called hydrothermal vents, which may be familiar to some students. A hydrothermal vent is a geyser on the seafloor. It continuously spews super-hot, mineral-rich water that helps support a diverse community of organisms. Many middle school students can begin to understand the difference between black and white smokers, and get an idea of how chemistry and physics tie into biology from learning about these hot spots. The different minerals that occur determine the type of smoker. The white smokers are the rarest and hottest type of vents, with the black smokers being slightly cooler and more numerous. A short PowerPoint show that lasts about 10 minutes with pictures and an introduction to the Gwynne Rife (rife@findlay.edu) is an associate professor of biology at the University of Findlay in Findlay, Ohio. 16 s c i e n c e s c o p e Summer 2006

2 Deep-sea fishing deep-sea vent communities is a good way to begin this experience. After discussions of how life can survive in such a cold, dark, and high-pressure environment, students are ready for more details about some of the animals that are residents of this area. I recommended beginning this activity with a 30- minute multimedia presentation about the deep-sea environment and hydrothermal vent communities. The internet offers numerous sites some available long-term, some that change as the knowledge base grows where students can view images of monsters of the deep and read about the latest discoveries (see Resources). Specific images of denizens of the deep can be found by searching for their scientific names. There are unfortunately sites that contain misinformation (one that called a basket sea star a fish instead of an invertebrate resides in cyberspace at the writing of this manuscript). Deep-sea facts should be double-checked with more than one source whenever possible to avoid passing on misinformation. For each of the fish or invertebrates, students should learn about their adaptations to the deep-sea environment. Very little is known about the creatures that live in the ocean depths. Most of the information is available on the internet. A short webquest focusing on the specific adaptation of a chosen species would be a great way to encourage a deeper understanding of the animal s habits. The majority of the deep-sea fauna have feeding parts that are capable of consuming creatures nearly as large as themselves. Because most of this habitat is desertlike with little food, fish of the deep ocean zones do not want to pass on a meal because it is a little too big for them to eat. Deep-sea fish generally have large recurved teeth, dislocatable jaws (if they have jaws at all), and bioluminescence, or glow-in-thedark organs and patches. Other interesting deep-sea animals may not use photophores, or glowing patches, but use other means to maximize their ability to survive in the deep ocean. Figure 1 lists some common deep-sea animals students like to learn about and some of their adaptations to the deep sea (see Resources for additional information). Bioluminescence Bioluminescence, or living light, is produced by a biochemical pathway and is either generated directly by the animal or by a symbiotic relationship between the fish or invertebrate and bacteria. Of the marine animal phyla, 14 have members that produce light, more than half of all animal phyla capable of bioluminescence. There are different wavelengths of light emitted by bioluminescent reactions; the most common color is a light blue glow, but some fish can emit red light that works something like night vision. Almost all marine bioluminescence is blue in color, for two related reasons. First, bluegreen light (wavelength around 470 nm) transmits farthest in water. The reason that underwater photos usually look blue is because red light is quickly absorbed as you descend. The second reason for bioluminescence to be blue is that most organisms are sensitive only to blue light they lack the visual pigments that can absorb longer (yellow, red) or shorter (indigo, ultraviolet) wavelengths. Summer 2006 s c i e n c e s c o p e 17

3 FIGURE 1 Some deep-sea animals Common name Scientific name Description Fangtooth fish, or orgrefish Anoplogaster cornuta Short, deep body with a large head and mouth. Covered with small, prickly scales. Opens big mouth and sucks prey inside. Small, recurved teeth trap prey inside. Tripod fish Bathypterois grallator Outstretched pectoral fins that resemble antennae. Pectoral fins help feel water vibrations and sense prey. Large fin rays in tail to stand on seafloor like a tripod. Pompeii worm Alvinella pompejana Invertebrate. Thrives in 80 C (176 F) water. Deep-sea isopod Bathynomus giganteus Young stay in marsupium until they can survive on their own. Excellent chemical sensors to locate food. Calyptogena clam Vesicomya pacifica Large as footballs. Invertebrate clams with bacterial symbionts to feed. Sea pig Scotoplanes spp. A sea cucumber (invertebrate). Very numerous in deep-sea mud. Lives at 3.4 km deep. Long-nosed chimera, or rattail or ghost shark Harriotta raleighana Sharp nose resembling a supersonic jet. Dorsal fins with venomous spine that can kill a person. Lives at 2.4 km deep. Gulper Saccopharynx lavenbergi Up to 1.8 m long with rows of sharp teeth. Eat prey whole, hence the name gulper. Victims travel to sack-gullet and into the stomach for digestion. FIGURE 2 Some bioluminescent deep-sea animals Common name Scientific name Description Wolftrap angler, or Prince Axel s wonder-fish Thaumatichthys axeli Bioluminescent organ projecting from its toothy jaws serves to light the habitat for this bottom-dweller. Lives up to 540 m deep. Viperfish Chauliodus macouni Hinged skull, allowing it to rotate up for swallowing large prey. Large stomachs. Various light organs, including one on a long dorsal fin that serves as a lure. Uses sharp teeth to impale its prey by swimming at them fast. The first vertebra acts as a shock absorber. Photophores all along sides body to signal and attract other viperfishes. Lanternfish Myctophum spp. Photophores on head, underside, and tail for attracting prey. Each species has a distinct pattern of lights and seeks out mate with the same pattern. Hatchetfish Sternoptyx obscura Ventral (belly) light organs, possibly to provide illumination that blends with the weak light from above (counterillumination). Very narrow (laterally compressed), like a knife. Hard to see looking up into the light. Can regulate the intensity and color of light to match the light filtering down. Each species has its own pattern. Dragonfish, or loosejaw Football fish (deep-sea angler) 18 s c i e n c e s c o p e Summer 2006 Malacosteus, Aristostomias, and Pachystomias spp. Himantolophus groenlandicus No scales. Ventral, and sometimes near-eye, photophores that emit nearly infrared wavelengths barely visible to a human eye. Can produce typical blue-green light from a separate organ. First deep-sea angler ever found. The original specimen washed ashore in Greenland in 1833; at 55 cm long, it is still the largest one on record. Has an illicium and esca to lure prey. Bristlemouth Cyclothone spp. Uses counterillumination to hide from predators. By lighting two rows of photophores on underside, it avoids casting a shadow on predators below and can virtually disappear. Vampire squid Vampyroteuthis infernalis Squid (invertebrate) with astonishing series of photophores; lights all over its body except for inner surface of web. Appears to turn on and off at will. At back of neck are clusters of more complex photophores. Behind base of fins, two more light organs, equipped with an eyelid that can close to shut off light. This squid has the largest eyes of any animal relative to body size. Fifteen-centimeter squid has eyeballs the size of a large dog s. Lights help it find prey in depths of 915 m.

4 The biochemical pathway that produces bioluminescence is probably too advanced for most middle school students, but it is interesting to note that the light that is given off is actually a byproduct of a reaction that must happen in the presence of oxygen, and is mediated by a enzyme know as luciferin. In the reaction an electron is moved to an excited state, and when the reaction is finished it is the energy released by the electron falling back into its unexcited state that releases the energy as light. Most deep-sea fish do not produce their own light directly, but have small depressions or sacs that house symbiotic bacteria that do use the chemical pathway. Whether they produce the light directly, or house bacteria that do, at least two chemicals are required one that produces the light, called a luciferin and the one that drives or catalyzes the reaction, called a luciferase. Bioluminescence is not the same as fluorescence or phosphorescence. In fluorescence (what glow-in-the-dark paint does), energy from a source of light is absorbed and reemitted as another photon. In bioluminescence, or chemiluminescence, the excitation energy is supplied by a chemical reaction rather than from a source of light. Even if the students are not able to understand the biochemistry of living light, they could see the relationship to the deep-sea environment and the benefit to an animal for this kind of adaptation. FIGURE 3 Deep-sea fish. These drawings or similar ones could be duplicated and used for this activity. Prince Axel s wonder-fish (A) uses the light organ inside its upper jaw to illuminate its surroundings. Deep-sea viperfish (B) uses light organs to attract prey and to warn other fish. Lanternfish (C) uses its light organs to recognize other fish of its kind. Hatchetfish (D) uses light organs along the bottom if its body for counterillumination. Football fish (E) one of the deep-sea anglers that has a lighted fishing lure to attract prey. Vampire squid (F) uses its many photophores to shimmer or flash to scare off a predator. A B C D E F Summer 2006 s c i e n c e s c o p e 19

5 BY BECOMING A BIOLUMINESCENT DEEP-SEA ANIMAL, STUDENTS CAN EXPERIENCE THE NEED FOR ADAPTATIONS IN ANIMALS OF THE DEEP SEA. The wrap-up After researching animals and seeing pictures of deep-sea creatures, students are easily led into a lively discussion of why animals would benefit from the ability to produce living light. Students often suggest that bioluminescence allows creatures to: attract food (lures to catch prey), communicate (to find each other, especially a mate), avoid being eaten (to scare off a predator or warn others of a predator s approach), and blend in (camouflage, counterillumination). A chart of some major animals from the deep-sea and their bioluminescent adaptation is in Figure 2. Students get black-and-white line drawings (see Figure 3) on heavy card stock that are relatively detailed and accurate representations of a deep-sea animal species. Glow-in-the-dark fabric paint is applied to the animals according to where they have photophores. This paint can be purchased at any craft shop or online (see Resources). One tube per student is a good amount. They can also choose several hues and trade colors. Each student does his or her own painting. The animal can then be cut out and glued to a craft stick. There is very little mess, though the project needs a place to dry for about two hours. After the paint and glue dry, students can do a number of things to experience the deep-sea environment. To show what bioluminescence may look like in the deep sea, take students into a dark room and let them swim their fish around. Students who have carefully applied paint to the correct areas of the fish can find other members of their species in a dark room. If several students have the same fish species, it gives them a great feeling for what it must be like for an animal to be alone in the dark trying to find company or food, or to try to determine the size of the fish from the type of light patterns it emits. Other ideas teachers have used to extend this activity include coloring several animals (including jellyfish, worms, and other bioluminescent organisms) and making a mobile to hang around the classroom, or having students put their creatures on a bulletin board to make a deep-seascape. By becoming a bioluminescent deep-sea animal, students can experience the need for adaptations in animals of the deep sea, and extend that to more familiar and perhaps less obvious adaptations all animals need to survive. Acknowledgment I would like to thank Katherine Noblet of the University of Findlay for the line drawings of the deep-sea critters. Additional reading Denton, E.J., P.J. Herring, E.A. Widder, M.F. Latz, and J.F. Case The roles of filters in the photophores of oceanic animals and their relation to vision in the oceanic environment. Proceedings of the Royal Society B 225 (1238): Douglas, R.H., and J.C. Partridge On the visual pigments of deep-sea fish. Journal of Fish Biology 50: Douglas, R.H., J.C. Partridge, and N.J. Marshall The eyes of deep-sea fish. I: Lens pigmentation, tapeta and visual pigments. Progress in Retinal and Eye Research 17: Gage, J.D., and P.A. Taylor Deep-sea biology. New York: Cambridge University Press. O Day, W.T., and H.R. Fernandez Aristostomias scintillans (Malacosteidae): A deep-sea fish with visual pigments apparently adapted to its own bioluminescence. Vision Research 14 (7): Partridge, J.C., and R.H. Douglas Far-red sensitivity of dragon fish. Nature 375: Widder, E.A., M.I. Latz, P.J. Herring, and J.F. Case Far-red bioluminescence from two deep-sea fishes. Science 225 (4661): Online resources Deep-Sea Pages people.whitman.edu/~yancey/realindex.html The Blue Planet ( The Deep segment) programmes/tv/blueplanet Glow fabric paint Deep-Sea Bestiary bestiary.html Paul H. Yancey, Deep-Sea Expert people.whitman.edu/~yancey 20 s c i e n c e s c o p e Summer 2006