Life in the Neighborhood

Image used with Permission, 2013. Image located at all other organisms on Earth, Pyrocystis fusiformis needs to eat. It does this through the process of photosynthesis (Miller 2010). Photosynthesis involves using energy from light photons to drive the production of sugars from CO2. This process takes place in the plastids (such as chloroplasts) within the cell. However, photosynthesis is not the only way P. fusiformis obtains its food. It can also feed on other planktonic species in its habitat. Because it can act as both an autotroph (making its own food) and heterotroph (eating other organisms for food), it is called a mixotroph (Miller 2010). An example of a heterotroph is the American Crocodile, and an example of an autotroph would be Pancake Prickly Pear Cactus.             

Image used with Permission, 2013. Image located at only does P. fusiformis eat, but it also gets eaten. It is an important food source for common marine organisms such as fish like the Atlantic Cod, baleen whales, and whale sharks, who obtain their food through filter-feeding (Miller 2010).            

The marine food web has an important place for P. fusiformis. As a phytoplankton, it is an essential producer in the world’s oceans by contributing to the total oxygen concentration. P. fusiformis also serves as a food source for other marine organisms, which helps maintain stability and diversity in the food web (Miller 2010).

An Oceanic Burglar Alarm

Pyrocystis fusiformis has an interesting way of deterring predators. It employs what is sometimes called the “Burglar Alarm Theory” (Fleisher and Case 1995). When in the presence of a predator, P. fusiformis becomes bioluminescent. The light it releases acts as a kind of burglar alarm, alerting other organisms of its location. These other organisms will then eat P. fusiformis’ predators. P. fusiformis does this in the hope that its predators will be attacked before it is attacked, much like a burglar alarm alerts authorities to the location of the burglar. This takes the pressure off of P. fusiformis and places it upon its predators instead (Fleisher and Case 1995). Because P. fusiformis tends to congregate in large groups, this strategy benefits the species overall (Miller 2010). Without this strategy, P. fusiformis’ predators would not be threatened and could potentially feed on the entire group of P. fusiformis. This strategy increases the chance that predators of P. fusiformis will be killed and eaten by other organisms, protecting the overall group of P. fusiformis at the expense of a few individuals. Overall, the luminescent genotype is favored (Miller 2010).            

Image used with Permission, 2013. light emitted from bioluminescent dinoflagellates such as Pyrocystis fusiformis not only serves to protect itself, but it also impacts the feeding efficiency of larger, predatory organisms that do not feed on P. fusiformis. The light produced by P. fusiformis acts as a kind of flashlight or searchlight by which predatory organisms such as fish and cephalopods can find and feed on other, non-bioluminescent organisms. Without this light, the predation success of the fish and cephalopods is greatly reduced. In contrast, as the amount of bioluminescent P. fusiformis organisms increases, predation on other non-luminescent prey increases (Fleisher and Case 1995). This makes sense because the more numbers of P. fusiformis present, the more light is produced, and the better predators can locate prey.

You may or may not have heard of what is called the Milky Seas Phenomenon. This understudied event that occurs in the oceans results in a milky white glow on the surface of the water, sometimes for days and over many miles. Originally, scientists thought P. fusiformis was the cause of this milky glow, since it congregates in groups and has the ability to bioluminesce. However, this idea was disputed when it was The Milky Seas Phenomenon. Image used with Permission, Nikos Pantazis (Flickr). Image located at that P. fusiformis emits flashes of light and not a steady glow. It is now believed that the bioluminescent bacteria Vibrio harveyi is at the root of this spectacle. V. harveyi is capable of producing an extended bioluminescent glow and lives on algal blooms on the water’s surface, so it is a likely candidate for causing Milky Seas. The broader implications and environmental impacts of Milky Seas have not yet been determined (Miller 2010).         

Pyrocystis fusiformis impacts other marine organisms as well as impacting humans. Humans find P. fusiformis useful in conducting bioassays. For example, it can be used in experiments to assess chemical contamination in certain areas. P. fusiformis is inexpensive and relatively easy to obtain and maintain compared to other, larger organisms, which makes it an ideal organism to use in such toxicity studies (Miller 2010). In addition, since P. fusiformis is a phytoplankton, it increases the oxygen concentration in the atmosphere. Humans and many other organisms require oxygen to live, and much of this oxygen is due to oceanic phytoplankton such as P. fusiformis. It also helps keep the marine food web stable by providing a food source to other organisms; humans in turn can use these organisms as a food source for themselves.            

While Pyrocystis fusiformis may be small and relatively unknown to the general human population, it has an important part to play in the world’s ecosystem.                

"Leave me alone, eat that other guy!"
        -Pyrocystis fusiformis

Want to know more interesting facts about Pyrocystis fusiformis? Go to Fun Facts.



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