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Home , Aquatic ecosystem

Bioluminescence in the aquatic environment

Saara Pörsti Academic writing 2018 Table of contents 1. Preface ...... 2 2. What is ? ...... 2 3. The chemistry behind bioluminescence ...... 2 4. The evolution of bioluminescence ...... 3 5. Functions ...... 3 5.1 Defending ...... 3 5.2 Lure ...... 4 6. Summary ...... 4 References ...... 5

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1. Preface

In the aquatic environment, light spectrum withdraws depending on wavelength, leaving most of the environment in darkness. When the surroundings are dark, purport of light modifies; life may not depend on sunlight, but bioluminescence. The studies of Haddock et.al submit that it is found globally, from terrestrial to littoral environment, deep ocean, salty to fresh waters (Haddock et.al, 2010) and tropical to cold areas (Widder, 2010). Bioluminescence is more prominent in the animal kingdom that is known, and it has also evolved to organisms approximately forty times; this declares the importance of light production in the animal kingdom (Haddock, et al. 2010). Widder and Johnsen clarify that limited amount of information is available about this biological phenomenon, and the most popular example are fire flies from terrestrial environment (Widder and Johnsen, 2000). Approximately 700 hundred species are known to obtain bioluminescence; 80% are marine animals (Widder, 2010). Haddock et al. notes that bioluminescence is found mainly from salty waters, but few larva and limpet species live in the Baikal that are bioluminescent; blooming plants and terrestrial vertebrates are not known to being able to light production (Haddock et.al, 2010). Haddock et al. state that it can only be speculated why bioluminescence is primarily found from marine environment. It is hypothesized that marine environment is more stable compared to terrestrial environment and they have longer -free evolution history. Sea water is also optically purer compared to fresh waters and (Haddock et.al, 2010).

2. What is bioluminescence? The studies of Navizet states that bioluminescence is the animal’s self-made light, which does not produce heat. The phenomenon is also called “cold light”, constituting it efficient to use as the light does not heat. Bioluminescence is chemical reaction that releases energy seen as light (Navizet, 2011) and it is found from vast spectrum of diverse colors and intensities (Widder, 2010). Widder points out that bioluminescence is produced in specific light organs whose place varies between species; the producer of the phenomenon varies. Some species produce the light by them self, but some have with organisms that provides bioluminescence (Widder, 2010). The reaction requires energy to act, so it inquires resources from the animal (Haddock, et.al., 2010)

3. The chemistry behind bioluminescence

The studies of Haddock et.al suggest although there are plural ways to produce bioluminescence; the main components are equivalent regardless of the animal. A photoprotein called luciferin, named after the fallen angel Lucifer, becomes oxidized by the impact of luciferase enzyme or photoprotein, depending of the animal. When luciferin is oxidized it becomes exited and produces light (Haddock et.al, 2010). Navizet reports that before functioning the luciferin molecule is prerequisite to react with ATP-molecule, adenosine triphosphate; the compound allows luciferase molecule to combine with ATP and luciferin. These 2+ reactions allow combination with oxygen and Mg , whose high energy reaction creates photon of light that is the byproduct of excitement. The color of light depends on the luciferase enzyme; function of the light depends on the color (Navizet, 2011). As said earlier, bioluminescence has evolved several times to organisms. Widder clears that it evolved in high seas most of the times hence marine environment has favorable conditions for light production for its stability. Sea water is blue colored since blue wavelength travels longest in water and as a corollary blue colored bioluminescence is the most common. Green is also common and found mainly from benthic environments

2 since increased turbidity of particles. Purple and red bioluminescence are rare, and their function and chemical reaction are still unknown (Widder, 2010). Haddock et.al suggest red light is used to see the pray; many are able too only blue wavelength, so some deep ocean predators obtain light organs near their eyes that produce red light. This gives them competitive advantage as they can spot pray without it been able to spot the predator (Haddock, 2010).

4. The evolution of bioluminescence Widder argues that when pursuing the evolution history of animals producing bioluminescence, it has not followed any phylogenetic line (Widder, 2010); and it has evolved over forty times for species (Haddockk, et.al., 2010). Haddock et.al correctly argues that bioluminescence is not only advantageous and paramount, but the reaction also effortless to evolve. The genuine origin is wearisome to extract, although it has been concluded that animals in the post-cambric era had bioluminescence by following the eating habits of animals (Haddockk, et.al., 2010).

5. Functions Haddockk et.al report that various species have bioluminescence, i.e. , , sponges and vertebrates. The light production is made by the animal itself in most cases; symbiotic bacteria living inside animal’s light organs are also known to produce bioluminescence. (Haddock, 2010). 5.1 Defending According to Widder some squid and fish species use counterillumination to confuse predators (Widder, 2010); when ocean is dark during night time bioluminescence illuminates the animal’s shadow from the surroundings when looking from deep to the surface. Squid species Eupryma scolopes have symbiotic Vibrio fisheri bacteria inside their light organs (Jones & Nishiguchi, 2004); symbiotic relations as these are species specific and Vibrio fisheri is a common example of well-studied bacteria that produces bioluminescence. (Miyashiro, 2012). The studies of Jones and Nishiguchi suggest that to match the intensity of produced light to environment’s’ light Eupryma scolopes species have specialized organs that are sensitive to light. Organs are connected to eyes so the intensity of produced light of the bacteria is controllable (Nishiguchi, 2004). Light organs’ have frequent tissue layers in addition to a lens that reflects and focuses the light in a right way; to adjust the intensity they have ink sacs. As oxygen is also needed to the chemical reaction, the animal can control its access to light organs (Jones & Nishiguchi, 2004). Vibrio fisheri produces bioluminescence if the concentration of the bacteria is solid enough in sea water according to Miyashiro. They communicate with autoinducer molecule that moves freely through cell membranes; when concentration is strong it triggers a chemical reaction inside the bacteria that enables bioluminescence production. When autoinducer molecule connects itself to LuxR-protein inside Vibrio fisheri, the protein reacts with DNA’s lux-operon molecule; when LuxR-protein is activated it starts the production of protein that permits bioluminescence; at the same time more autoinducer is produced. (Miyashiro, 2012)

Jones and Nishiguishi concludes that light production is well regulated for its need of energy; hypothesis say that Eupryma scolopes free the bacteria out during day and hid under sand, and for night they rise the bacteria- concentration inside the light organs and hunt during dark time. (Jones & Nishiguchi, 2004). Widder underlines that confusing predators is one of the most common ways to exploit bioluminescence; some animals use bioluminescence cloud to confuse predators by blinding them or marking them with bioluminescence “glue” for secondary predators (Widder, 2010). A glowing animal is easy to spot in the darkness. Robinson’s et.al studies’ about Vampyroteuthis infernalis, vampire squid, show an example of an animal using glowing glue to distract the predators. The squid spits out bioluminescent glue and marks the predator for

3 bigger ones. As the predator convalesces and realizes what happened, Vampyroteuthis infernalis escapes; its movements are slow and eyesight defective. Vampyroteuthis infernalis has also light organs in its tentacles; by severing one for predator it saves itself as the predator is confused and left with only one tentacle. (Roinson et.al 2003). Bioluminescence expresses also poisonousness; sea anemones avoid predators showing they are uneatable. (Haddockk, et.al, 2010). 5.2 Lure The studies of Nealson and Hastings shows that bioluminescence is effective for luring pray and partner; anglerfishes are fish of the teleost order Lophiiformes that lure partner and pray with a glow. Female anglerfish have symbiotic relationship with Photobacterium bacteria; they live inside the fish’s lure coming out from its forehead. The bacteria provide safe living conditions and nourishment whilst the anglerfish has a lure to tempt pray and partner (Nealson & Hastings,1979). The male is much smaller and doesn’t have bioluminescence; it searches a female and attaches itself to the female’s orifice; their blood systems combines, and the male is carried by the female where ever it swims (Haddock, et.al, 2010).

6. Summary Bioluminescence has evolved over forty times which underlines its importance for animals; resources are ready to be sacrificed for it. Humans are only beginning to understand the importance of bioluminescence and its role in the aquatic . Maybe it will be brought to our every-day-life in the future? It has already found its way to medical industry; doctors are able to spot metastatic tumors from patients with cancer by making tumors glow with bioluminescence. People have also manipulated the genes of a rabbit and a tobacco plant and made them glow in the dark. Where is the limit and could it be possible for humans to benefit from bioluminescence? Many ethical questions remain to be solved if humans’ interest towards bioluminescent grows. How much can we manipulate organisms for our own interest? If it is possible to diminish energy-waste by manipulating the genes of a tree, make them glow and plant them beside routes should it be allowed? Glowing trees will have an affect for the animals and the whole ecosystem the trees would be planted, but on the other hand, it would help with the energy problem we are facing.

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References Bassler; B. & Losick, R. 2006. Bacterially speaking. Cell 125: 237−246.

G. Gerrish & J. Morin. 2008. Life Cycle of a Bioluminescent Marine Ostracode, Vargula (Myodocopida: Cypridinidae). Journal of Crustacean Biology 28: 669−674. S. Haddock, M. Moline, J. Case. 2010. Bioluminescence in the Sea. Annual Review of Marine Science 2: 443-493. B. Jones & M. Nishiguchi. 2004. Counterillumination in the Hawaiian bobtail squid, Euprymna scolopes Berry (Mollusca: Cephalopoda). 144: 1151–115

T. Miyashiro & E. Ruby. 2012. Shedding light on bioluminescence regulation in Vibrio fischeri. Molecular Microbiology 84: 795−806.

Navizet, Y. Liu, N. Ferré, D. Roca-Sanjuán & R. Lindh. 2011. The Chemistry of Bioluminescence: An Analysis of Chemical Functionalities. Chemphyschem 12: 3064−3076.

K. Nealson & J. Hastings. 1979. Bacterial Bioluminescence: Its Control and Ecological Significance. Microbiological reviews 43: 496−518.

B. Robinson, J. Hunt, K. Reisenbichler & S. Haddock. 2003. Light Production by the Arm Tips of the Deep-Sea Vampyroteuthis infernalis. Biological Bulletin 205:102–109

E. Widder. 2010. Bioluminescence in the Ocean: Origins of Biological, Chemical, and Ecological Diversity. Science AAAS 328: 704−708.

E. Widder & S. Johnsen. 2000: 3D spatial point patterns of bioluminescent : a map of the ‘minefield’. Journal of Plankton Research 22: 409−420.

Cover picture by Chris Newbert

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