From Wikipedia,
the free encyclopedia.
Bioluminescence is the
production and emission of
light by a living
organism as the result of a
chemical reaction during which
chemical energy is converted to
light energy. The name originates
from the
Greek bios for "living"
and the
Latin lumen "light".
Bioluminescence may be generated
by
symbiotic organisms carried
within a larger organism. It is
generated by an enzyme-catalyzed
chemoluminescence reaction,
wherein a
luciferin (a kind of
pigment) is
oxidised by a
luciferase (a kind of
enzyme).
Adenosine triphosphate (ATP)
is involved in most instances. The
chemical reaction can be either
external to cells, or an
intracellular process. The
expression of
genes related to
bioluminescence in
bacteria is controlled by an
operon called
lux operon.
Artistic rendering of
bioluminescent
Antarctic krill
(watercolor by Uwe Kils)
Characteristics of the
phenomenon
Bioluminescence is a form of
luminescence, or "cold light"
emission; less than 20% of the
light is generated by
thermal radiation. It should
not be confused with
fluorescence,
phosphorescence or
refraction of light.
90% of
deep sea marine life is
estimated to produce
bioluminescence in one form or
another. Most marine
light-emission belongs in the
blue and
green
light spectrum, the
wavelengths that have the most
powerful penetrating power in
water. However, certain
loose jawed fish emit
red and
infrared light.
Non-marine bioluminescence is
less widely distributed, but a
larger variety in colours is seen.
The two best known forms of
land–bioluminescence are
fireflies and
New Zealand
glow worms. Other
insects,
insect larvae,
annelids,
arachnids and even species of
fungi have been noted to
possess bioluminescent abilities.
Most forms of bioluminescence
are brighter (or only exist) at
night, following a
circadian rhythm.
Adaptations for
bioluminescence
There are four main accepted
theories for the
evolution of bioluminescent
traits:
-
Camouflage
- Attraction
- Repulsion
- Communication
Camouflage
Attraction
Bioluminescence is used as a
lure to attract
prey by several
deep sea fish such as the
anglerfish. A dangling
appendage that extends from
the head of the fish attracts
small animals to within striking
distance of the fish. Some fish,
however, utilize a
non-bioluminescent lure.
The
cookiecutter shark uses
bioluminescence for camouflage,
but a small patch on its
underbelly remains dark and
appears as a small fish to large
predatory fish like
tuna and
mackerel. When these fish try
to consume the "small fish", they
are bitten by the shark.
Dinoflagellates have an
interesting twist on this
mechanism. When a
predator of
plankton is sensed through
motion in the water, the
dinoflagellate luminesces. This in
turn attracts even larger
predators which will consume the
would-be predator of the
dinoflagellate.
The attraction of
mates is another proposed
mechanism of bioluminescent
action. This is seen actively in
fireflies who utilize periodic
flashing in their abdomens to
attract mates in the mating
season. In the marine environment
this has only been well-documented
in certain small
crustacean called
ostracod. It has been
suggested that
pheromones may be used for
long-distance communication, and
bioluminescent used at close range
to "home in" on the target.
The
honey mushroom attracts
insects using bioluminescence,
hoping the insects will help
disseminate the fungus'
spores into the environment.
Repulsion
Certain
squid and small
crustaceans utilize
bioluminescent chemical mixtures,
or bioluminescent
bacterial slurries in the same
way as many squid use
ink. A cloud of luminescence
is expulsed confusing, or
repelling a potential predator
while the squid or crustacean
escapes to safety.
Communication
Bioluminescence is thought to
play a direct role in
communication between bacteria
(see
quorum sensing). It promotes
the symbiotic induction of
bacteria into host species, and
may play a role in colony
aggregation.
Biotechnology
Bioluminescent organisms are a
target for many areas of research.
Luciferase systems are widely used
in the field of
genetic engineering as
reporter genes (see
green fluorescent protein, and
picture left).
Vibrio symbiosis with numerous
marine invertebrates and fish,
namely the
Hawaiian bobtail squid (Euprymna
scolopes) is a key
experimental model for
symbiosis,
quorum sensing, and
bioluminescence.
The structure of
photophores, the light
producing organs in bioluminescent
organisms, are being investigated
by
industrial designers.
Some proposed applications of
engineered bioluminescence
include:
-
Christmas trees that don't
need lights, reducing dangerous
electronics
- glowing trees to line
highways to save government
electricity bills
-
agricultural crops and
domestic plants that luminesce
when they need watering
- new methods for detecting
bacterial contamination of meats
and other foods
- bio-identifiers for escaped
convicts and mental patients
- detecting bacterial species
in suspicious corpses
- novelty pets that
bioluminesce (rabbits,
mice,fish
etc.)
Organisms that bioluminesce
All cells produce some form of
bioluminescence within the
electromagnetic spectrum, but most
is neither visible nor noticeable
to the naked eye. Every organism's
bioluminescence is unique in
wavelength, duration, timing and
regularity of flashes. Below
follows a list of organisms which
have been observed to have visible
bioluminescence.
Image of hundreds of
agar plates cultured
with a species of
bioluminescent marine
bacteria displayed in a
pattern as an art exhibit
called "Bioglyphs" at
Montana State
University–Bozeman.
Non-marine organisms
Fish
Marine invertebrates
Plankton and microbes
