Photinus marginellus firefly produces a chemical reaction inside of their abdomen, where their light organs are located. This chemical reaction allows the Photinus marginellus to release their bioluminescent glow. The firefly controls the beginning and end of the chemical reaction, meaning, the species is able to start and stop its light emission on command, and when needed (Branham, 2005). The reasons for their bioluminescent glow would be for a source of survival, and a contributor to sexual selection (Branham, 2005). The presence and repetition of the glows can be stated as warning signs to communicate their bitter distastefulness to their predators (Lewis, et al., 2012). The flash patterns of the glows are also used for communication between similar species. The Photinus marginellus have flash patterns that are unique to their species, and the flash patterns are used to discriminate between sexes (Branham, 2005). Female Photinus fireflies choose their mate depending on the specific flash pattern of a male. The higher the flash rate and intensity, the more attractive the male will be to the female, and will therefore, aquire a higher chance of being chosen by the female for reproduction (Cratsley, 2004).
    The bioluminescence benefits the organisms by means of survival, but is also used more and more to benefit humans. Scientists are interested in studying the bioluminescence to: synthetically trace the ATP and calcium in the cell, to illustrate the progression of infection, and to assist in AIDS research (Klug, 2001). The bioluminescent genes can be injected into harmful bacteria, causing them to glow. Scientists are then able to watch the infection spread, and are able to detect where the antibiotics are most effective based on where the glowing occurs (Klug, 2001). The bioluminescence can further be used to inject into diseased cells as well. The diseased cells will glow with the bioluminescence which then makes it easier for scientists to detect changes in cells and then can further be used to study many diseases, from cancer to muscular dystrophy (Pfeiffer, 2009).
    The Photinus marginellus males are the only sex that emits light on a regular basis. The male firefly uses courtship to attract a female. If the female is interested, she will respond with short, rapid glows in response. The intensity of light the male can emit, correlates with the amount of nuptial gift the male can provide the female when reproducing (Cratsley, 2004). (Click here for more information on nuptial gifts in correlation with reproduction).

Permission granted: Tom MurrayCourtesy of Wikipedia: Bruce Marlin

Figure 1. Shows the two organisms involved in the predatory/prey relationship. The organism on the right is the female Photuris. On the left is the Photinus marginellus.

      The Photuris firefly, on the right side in Figure 1, will mimic the Photinus marginellus female flash signals, which then attract the male Photinus marginellus (left side Figure 1). The Photinus marginellus males are then attacked, paralyzed, and then eaten by the Photuris females (Eisner, et al., 1997). The Photuris females gain many nutrients from the male Photinus marginellus, that they would not be able to acquire on their own. The Photinus male also have a defensive steroid called lucibufagins that the Photuris fireflies do not have (Eisner, et al., 1997). Along with nutrients, the Photuris firefly will acquire the lucibufagins steroid for its own use of defense to predators. This is a predatory symbiosis, and works unfortunately for the Photinus marginellus. The Photinus marginellus males are in fact killed through this process of mimicry from a predator.
    Although the Photinus marginellus can be tricked through mimicry, it does however, have the ability to eject the steroid lucibufagins to an oncoming predator, which make them inedible to the predator (Branham, 2005), such as a bird or lizard for instance. When the Photinus marginellus are attacked, they release drops of blood into the predator. The blood contains the chemical lucibufagins, which is said to taste very bitter, and can even be poisonous to some animals (Pfeiffer, 2009). Many animals have adapted to stay away from these fireflies, and avoid eating them at all costs.
    Due to the chemical adaptations to deter predators, and the complex system of light production for interaction, the Photinus marginellus species have been able to achieve sexual selection, and most importantly, are able to adapt to survive in their environment. The interaction between species, and within species, is therefore, the most important adaptation for survival for the Photinus marginellus.

      The Photinus marginellus has adapted to many ways of survival from the unique flashes the organism signals to deter predators, to the ejection of a steriod called lucibufagins causing the Photinus marginellus to taste extremely bitter. To elaborate in more detail concerning the amazing lucibufagins steriod, or more cool facts in general, continue onto the facts page for more information!

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