Interactions
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).
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!