Adaptation
Every
animal has a body composition that is fit and adapted to the habitat
that they reside within. Photinus marginellus species live
within the terrain of the woods and underneath the cover of leafy underbrush.
To fit in with this environment that can change from hot/tropic
to cold the Photinus marginellus need to have a body that can adapt
to any type of environment they migrate to. Different things such as
their chitonous exoskeleton, appendages, and light organelles help
Photinus marginellus navigate within their environment.
These means of adaptation all play a role to help in their survival.
A distinct feature of being an
insect is having a exoskeleton. An exoskeleton is comprised of
chitin and is found on the outside of an insect, by means of
protection. (Click
here for another organism who has a chitonous exoskeleton). The exoskeleton is
an attachment site for muscles and provides support for the whole
organism. Most Insects with an exoskeleton require a process called
molting. For the Photinus marginellus molting occurs during each
stage of its life process or cycle by ridding of the exoskeleton
that is currently has to make room for the new skeleton that is
underneath it, which allows the firefly to grow bigger. The
only down side to this part of their life cycle is that after the
molting has occurred, the Photinus marginellus is then
vulnerable because of the
new exoskeleton it obtained due to the skeleton not yet strengthened or hardened
enough to protect the insect properly (Hadley, Debbie, 2013).
The Photinus marginellus has two different styles of exoskeleton
which has been caused by a mutation. The first style of exoskeleton
that the Photinus marginellus possesses is an exoskeleton with a
dark pattern on the top. The dark area on the top has a black area on the inside
surrounded by a yellow outline. The other style is a light pattern that is
the same as the other darker pattern except instead of a black color
on the top, the
color is more of a light brown to a tan. These differences in color
are due to an evolutionary mutation. Both insects seem to survive
equally well (Luk et al,
2011). The Photinus marginellus exoskeleton has many other purposes
than color.
Figure 1. Depicts the distinct body regions of the Photinus pyralis, which is closely
related to Photinus marginellus. This photograph shows the
sheath wings. The uppermost wing is hard for protection, while the
bottom wing remains flexible for flight.
*Exoskeleton advantages:
*Exoskeleton Disadvantages
-covers the muscles and other
- limits the possible size of the animal
soft tissues from harm.
-Surface area to volume ratio is limited
- Better protected against immediate attacks
- The outer layer is very strong and resists
compression.
Aside from providing
colors to the organism, The Photinus marginellus
exoskeleton has more beneficial purposes. The
exoskeleton for the Photinus marginellus is the attachment site for
six jointed or segmented legs, two antennae, and a divided body that
consists of three different parts that are called the head, thorax
and the abdomen.
The head houses
both the antennae, which are used to find food and notice enemies,
along with housing the eyes. Photinus marginellus has compound eyes
which have multiple light-sensitive sensors and each one has its one
refractive system that helps to form part of the entire image
(Farlex, 2013; Luk et al, 2011). The compound eye is very
beneficial to Photinus marginellus because the eyes are able to pick
up more light and movement faster than a simple eye. This gives the
Photinus marginellus a faster reaction time, which is good because
of its small size (Museum of Science Boston, 2013).
Photinus marginellus uses
its six segmented legs to crawl around the forest environment which
it inhabits. The six segmented legs are found on the thorax; the
middle section of the body, along with the wings and the light
organelles in the back of the abdomen to help with mating signals
and mimicry (McKenzie, J. 2001). The thorax is the main site
and adaptation for movement. The legs are all segmented which
allow for a full range of motion that help the firefly move
throughout its terrestrial environment by way of walking or
crawling. Next are the wings that are used for flying. The outermost
wing is called Elytra which is a hard front wings that serve as
protective covers for membranous hind wings. The back wing is the
more flexible
wing which is used for flight(Fig 1) (Kinsey, B., 2005; Museum of
Science, Boston, 2013).
The last
section of the organism is the abdomen. The abdomen is segmented and also
happens to be where the light organelles
are located. (See the
Reproduction page for more information on the benefits of the
light organelles). The light organs are the way to tell the difference between
the male and the female. The light organelles of a female
Photinus marginellus is located only
on the second to last section of the abdomen (Fig 2). The male light
organelle is located on the last two sections of the abdomen (Museum of
Science of Boston, 2013). To find out more information and for
a
better understanding on how to read a flash chart try going to the
Museum of Science, Boston website. The flash chart shows the different
ways that the Photinus marginellus use the light
organelles to
communicate. Another place to look for more
information about different body plans and see amazing pictures that
have both Photinus marginellus and others fireflies look
into the Canadian
Journal of Arthropod Identification,
"The Fireflies of Ontario (Coleptera: Lampyridae)" it will show
you more of the connections between different species of
Photinus based on different body parts and body plans.
Figure 2. Shows the Photinus marginellus and the light organelles located in the abdomen. This figure distinguishes this particular Photinus marginellus is a female due to the light organ only visible on the second to last section of the abdomen.
Without the protective exoskeleton, the Photinus marginellus would not be able to function physically. The exoskeleton allows for this locomotion, but the nutrients for growth are just as important for physical health of the organism. Check out the nutrition page to find out what the Photinus marginellus eats to obtain its essential nutrients!