BIOCHEMICAL ADAPTATIONS
Bioluminescence of marine
organisms
Clusterwink snail
Light in water
A light ray is composed of seven colours. These seven colours are
Violet, Indigo, Blue, Green, Yellow, Orange and Red (VIBGYOR).
The light ray undergoes refraction when it hits water.
The upper 10 to 15 metres of water absorb the red colour. At 25 metres under water the red colour is not
visible, because the red colour does not reach this depth.
Similarly orange rays are absorbed at 30 to 50 metres,
yellow at 50 to 100 metres,
green at 100 to 200 metres,
and finally, blue beyond 200 metres .
So the colour of seas and oceans seems blue because this colour is dispersed in the first 200 meters
Violet and indigo above 200 metres.
Due to successive disappearance of colour, one layer after another, the ocean progressively becomes darker,
i.e. darkness takes place in layers of light.
Several processes make the light in water to vanquish gradually ;
among these are light refraction , photolysis , absorption by the different water particles and minerals
dissolved in water and the hanging materials in water and the living creatures along with its organic
wastes
The darkness in the seas
Measurements made with today's technology have revealed that between 3 and 30 %
of the sunlight is reflected at the surface of the sea.
Then, almost all of the seven colours of the light spectrum are absorbed, one after
another, in the first 200 metres, except for blue light.
Below a depth of 1,000 metres, there is no light at all .
As the light energy travels through the water, the molecules in the water
scatter and absorb it.
At great depths, light is so scattered that there is nothing left to detect.
Only the very top layers of the ocean get enough light to support plants,
and most of the truly abundant animal life is crowded into the top 200
meters.
This upper region is called the photic zone. Almost all of the marine
plants and tiny microscopic marine organisms engaged in
photosynthesis can thrive only in the photic zone.
The aphotic zone (without light) is the portion of an ocean where there
no sunlight. It is formally defined as the depths beyond which less than
1% of sunlight penetrates.
The aphotic zone
From 1,000 meters below the surface, all the way to the sea floor, no sunlight penetrates
the darkness; and because photosynthesis can’t take place, there are no plants, either.
Most food in this zone comes from dead organisms sinking to the bottom of the ocean from
overlying waters.
Organisms who live at the deep sea vents can’t rely on the Sun; instead, many of them rely
on the chemicals that come out of the vents.
In the deep-sea vents, for example, chemosynthetic bacteria (rather than photosynthetic
species) form the basis of the food chain.
These bacteria obtain energy from chemical sources such as hydrogen sulfide instead of
from sunlight.
The depth of the aphotic zone can be greatly affected by turbidity and the season of the
year.
Bioluminescence is essentially the only light found in this zone.
Animals sometimes make their own light; certain species of deep sea fish and jellyfish have
special light-producing cells.
CHEMOSYNTHESIS
At the heart of these deep-sea communities is a process called chemosynthesis.
Chemosynthesis is the use of energy released by inorganic chemical reactions to produce
food.
It is analogous to the more familiar process of photosynthesis.
In chemosynthesis, bacteria grow in mineral-rich water, harnessing chemical energy to make
organic material.
Chemosynthesis can sustain life in absolute darkness.
The most extensive ecosystem based on chemosynthesis lives around undersea hot springs.
Boiling hot, saturated with toxic chemicals and heavy metals, and more acidic than vinegar,
vent waters are deadly to most marine animals.
This noxious brew is paradise to the bacteria that coats the rocks around the vent in thick
orange and white mats.
The bacteria absorb hydrogen sulfide streaming from the vents, and oxidize it to sulfur.
They use the chemical energy released during oxidation to combine carbon, hydrogen, and
oxygen into sugar molecules.
The largest and most abundant vent creatures are tube worms and giant white clams—animals that thrive because they
have developed a symbiotic, or mutually beneficial, relationship with the bacteria.
Bacteria live within the hard-shelled animals where they are protected from predators.
The tube worms and clams receive a built-in food supply because they absorb nutrients directly from the bacteria.
SUB-SURFACE WAVES
Scientists have only recently discovered that there are sub-surface waves, which "occur
on density interfaces between layers of different densities.“
These internal waves cover the deep waters of seas and oceans because deep water has
a higher density than the water above it.
Internal waves act like surface waves. They can break, just like surface waves.
Internal waves cannot be discerned by the human eye, but they can be detected by
studying temperature or salinity changes at a given location.
When light rays reach the surface of the ocean they are reflected by the wave surface
giving it a shiny appearance.
Therefore the waves reflect light and cause darkness.
Therefore the ocean has two parts:
-the surface characterized by light and warmth
- the depth characterized by darkness.
The surface is further separated from the deep part of
the ocean by waves.
The darkness begins below the internal waves.
Even the fish in the depths of the ocean cannot see;
their only source of light is from their own bodies.
Biological Light in the Ocean Darkness
As darkness descends, the water becomes alive with displays of bioluminescence -- living
light produced by a myriad of organisms -- that has a major impact on virtually all
biological communities.
In the ocean, bioluminescent organisms are everywhere, inhabiting all depths covering all
the world's oceans.
The twilight zone-The twilight, or mesopelagic, zone, and extends from 200m to 1,000m
down. This zone appears deep blue to black in color. Animals living here have various
adaptations for living in the dimly lit waters.
Some species have enormous eyes to find food. To avoid being eaten, many are
transparent, including squid and crustaceans. Some fish have silvery reflective scales to help
make them 'invisible‘.
Some examples of bioluminescencent organisms :
-The cells that produce bioluminescence highlight breaking waves with streaks of electric
blue light, and trace the paths of swimming fish.
-The red tide phytoplankton use their flashes as a burglar alarm so they won't get eaten;
in this case, the "burglar" is the animal trying to eat them. In doing so, it stimulates the
cells to make flashes of light, attracting still other predators which try to eat the burglar.
The dark depths
Almost no light penetrates below 1,000m. The water is cold, reaching 3ºC, and contains very
little oxygen. The pressure is enormous, up to 1,000 times that on the surface. These dark
waters include the bathypelagic (1,000-4,000m), abyssopelagic (4,000m to the ocean floor) and
hadopelagic (water in ocean trenches) zones.
The deep sea effects
The deep sea is much poorer in productivity than shallower regions.
The fish tend to be much smaller than on the surface, with minimal bone
structure and more jelly-like flesh.
They are therefore slower and less agile than fish living near the surface.
They also tend to grow much more slowly than surface fish.
Some take many years to reach sexual maturity.
What is Bioluminescence
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
the pigment luciferin is oxidised by the enzyme luciferase.
Adenosine triphosphate (ATP) is involved in most instances.
The chemical reaction can occur either within or outside of the cell.
In bacteria, the expression of genes related to bioluminescence is controlled by
an operon called the lux operon.
Bioluminescence is mainly a marine phenomenon. It is not found in freshwater.
On land, it is seen only in a few species of fungi and insects.
How organisms use bioluminescence
Bioluminescence serves different purposes.
-Angler fish grow luminescent bacteria in a special structure which dangles at the end of a
stalk projecting from their forehead. In the perpetual darkness of the deep sea these fish
attract prey by their glowing lures.
-Still other fish produce far-red beams of light from areas on their cheeks. Because most
deep-sea animals can only see blue colors, the red luminescence serves as an invisible
searchlight for finding prey or mates.
-Certain squid and fish utilise luminous bacteria as symbiotic sources of light , and the
symbionts have physiological features which are of potential advantage in the association.
-Jellyfish so delicate that they disintegrate when touched emit brilliant displays of light
when disturbed.
In summary, glowing helps attract mates, lure pray or confound predators
hunt prey, defend against predators.
Bioluminescent Light
Bioluminescenceis the emission of visible light by biological systems, which arises from
enzyme-catalyzed chemical reactions.
Most marine bioluminescence is expressed in the blue-green part of the visible light
spectrum. These colors are more easily visible in the deep ocean.
Most marine organisms are sensitive only to blue-green colors. They are physically unable to
process yellow, red, or violet colors.
Few organisms can glow in more than one color. The so-called railroad worm (actually the
larva of a beetle) may be the most familiar. The head of the railroad worm glows red, while its
body glows green. Different luciferases cause the bioluminescence to be expressed differently.
Most organisms use their light organs to flash for periods of less than a second to about 10
seconds. These flashes can occur in specific spots, such as the dots on a squid. Other flashes
can illuminate the organism's entire body.
Bioluminescence, Florescence and
Phosphorescence
• Bioluminescence is not the same thing as
fluorescence.
• Florescence does not involve a chemical reaction.
In fluorescence, a stimulating light is absorbed
and re-emitted.
• The fluorescing light is only visible in the
presence of the stimulating light.
• Phosphorescence is similar to florescence, except
the phosphorescent light is able to re-emit light
for much longer periods of time.
• Glow-in-the-dark stickers are phosphorescent.
Anatomic Distribution
The tissue distribution of the components of the bioluminescent system
within organisms, is quite varied.
The anatomic location of bioluminescence gives clues as to the source of
component synthesis, storage, transport, and the functional role of the
luminescence.
One key organ is the "photophore" or the light producing organ, quite
evidently seen in many luminous fish and very vividly in cephalopods.
Photophores are normally made up of complex photogenic (light
emitting) cells.
bioluminescence: photogenic organ of a
hatchetfish
What is needed for bioluminescence?
• In general, bioluminescence involves the combination of two types
of substances in a light-producing reaction.
• One is a luciferin, or a light-producing substance.
• The other is a luciferase, or an enzyme that catalyzes the reaction.
• In some cases, the luciferin is a protein known as a photoprotein,
and the light-making process requires a charged ion to activate the
reaction.
• Photoproteins do not display typical enzyme kinetics as seen in
luciferases. Instead, when mixed with luciferin, they display
luminescence proportional to the amount of the photoprotein.
• The luciferin-luciferase reaction can also create byproducts like
oxyluciferin and water.
Photoproteins
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Most bioluminescent reactions involve luciferin and luciferase. Some reactions,
however, do not involve an enzyme (luciferase). These reactions involve a chemical
called a photoprotein. Photoproteins combine with luciferins and oxygen, but need
another agent, often an ion of the element calcium, to produce light.
Photoproteins were only recently identified, and biologists and chemists are still
studying their unusual chemical properties. Photoproteins were first studied in
bioluminescent crystal jellies found off the west coast of North America. The
photoprotein in crystal jellies is called "green fluorescent protein" or GFP.
Photoproteins are named for the marine organisms from which they are isolated,
"aequorin" and "clytin" from the jellyfish, Aequorea and Clytia, and "obelin" from
the hydroid Obelia.
Many other bioluminescent marine organisms also employ photoproteins, but only
these three have had their spatial structures determined. As these structures are
highly similar, they are regarded as a sub-class of the also similar and far larger
class populated by the many calcium-binding proteins.
photoproteins
• The amino acid sequences of the photoproteins from six different
species of Hydrozoa within the phylum Cnidaria, have been
determined, and they are highly homologous, i.e., many of the
amino acid residues occur in identical positions in each sequence,
or the position is occupied by a similar residue, and this is usually
taken to mean that these photoproteins arose from a common
ancestor protein
• Also on the basis of their primary sequence homology, they all
would be expected to have the same three-dimensional structure.
The purified photoproteins have a yellow color due to the tightly
bound reactive molecule, a 2-hydroperoxy derivative of
"coelenterazine" (Figure).
Structure of the Ca2+-regulated photoprotein obelin from Obelia
geniculata (PDB code 1JF0). The N-terminal alpha-helices are green
and the C-terminal red. The hydroperoxycoelenterazine substrate is
the blue stick representation buried between green and red alphahelices.
What is needed for bioluminescence?
• In addition to luciferin, oxygen, and luciferase,
other molecules (called cofactors) must be
present for the bioluminescent reaction to
proceed.
• Cofactors are molecules required by an enzyme
(in this case luciferase) to perform its catalytic
function.
• Common cofactors required for bioluminescent
reactions are calcium and ATP, used to store and
release energy in all organisms.
Hydrolysis of ATP
LUCIFERINS
• Lots of different substances can act like luciferins and luciferases,
depending on the species of the bioluminescent life form.
• For example, the luciferin coelenterazine is common in marine
bioluminescence.
• Dinoflagellates that obtain food through photosynthesis use a
luciferin that resembles chlorophyll. Their luminescence is brighter
after very sunny days. Some shrimp and fish appear to manufacture
their luciferin from the food they eat.
• The luciferins of some marine fishes, squids, crustaceans and
coelenterates are of very similar chemical structure, though
differing markedly from the luciferins of non-marine forms.
Luciferases
• Luciferase is an enzyme. The interaction of the
luciferase with oxidized (oxygen-added) luciferin
creates a byproduct, called oxyluciferin. More
importantly, the chemical reaction creates light.
• Bioluminescent dinoflagellates produce light
using a luciferin-luciferase reaction. The luciferase
found in dinoflagellates is related to the green
chemical chlorophyll found in plants.
Dinoflagellate luciferase catalytic domain
Luciferases
• Luciferases belong to a class of redox enzymese with different affinities for
luciferins:
– EC 1.13.12.5
• Renilla-luciferine 2-monooxigenase; Renilla-type luciferase; Aequorine;
Obelina; Luciferase (Renilla luciferina)
– EC 1.13.12.6
• Cipridina-luciferina 2-monoossigenasi; Cipridina-type luciferasi;
Luciferasi (Cipridina luciferina); Cipridina luciferasi
– EC 1.13.12.7
• Fotinus-luciferina 4-monooxigenase (ATP-ase); Luciferasi delle lucciole;
Photinus pyralis luciferasi
– EC 1.13.12.8
• Watasenia-luciferina 2-monooxigenase; Watasenia-type luciferasi
– EC 1.13.12.13
• Oploforus-luciferin 2-monooxigenase; Oploforus luciferasi
– EC 1.14.99.21
• Latia-luciferina monooxigenase (demetilante); Luciferasi (Latia
luciferina)
A schematic ribbon diagram of the crystal structure of luciferase domain 3 (D3). The barrel
is composed of 10 anti-parallel beta strands (blue). The "lid" is composed of three
regulatory alpha helices (green and cyan). The active site is located on the inside of the
barrel, and is not accessible with the regulatory "lid" closed. Other features include a
small C-terminal domain (red), and proline-rich sequences flanking the barrel (purple).
A stereo view of the interior of the luciferase barrel showing the arrangement of the
amino acids that compose the active site. The amino acid side chains are shown as sticks
(black) on a background of the beta strands (green). In this view, the regulatory helical
bundle has been removed for clarity. Water molecules (red spheres) form hydrogen
bonds (dotted lines) with active site residues. The water molecules occupy space in the
active site that would be occupied by luciferin during the chemical reaction.
Structures of two coelenterate, a bacterial and a firefly luciferase.
The structures for the three phyla are very different, which reflects the different
substrates and chemical reactions for each enzyme.
LUCIFERASE REACTION
adenylation of luciferin
oxygenation of adenyl-luciferin
The reaction proceeds in two parts: the adenylation of luciferin, followed by the oxygenation of adenyl-luciferin.
The adenylation step activates luciferin as an enzyme-adenyl-luciferin complex, which is analogous to the activation of
fatty acids by acyl-CoA ligases (based on homology, beetle luciferases are thought to have evolved from acyl-CoA
ligases, retaining their catalytic mechanism for adenylation).
In the second step, luciferase acts as an oxygenase on adenyl-luciferin to produce oxyluciferin and carbon dioxide, the
decay of oxyluciferin producing a photon of light.
Beetles/Fireflies
Luciferases from click beetles, fireflies, and railway worms catalyze the ATPdependent decarboxylation of luciferin (Figure).
An AMP derivative of luciferin is formed, which subsequently reacts with O 2 .
Cleavage of this dioxy derivative results in the emission of light characterized by
wavelengths ranging from 550 nanometers (2.17 × 10 −5 inches; green) to 630
nanometers (2.48 × 10 −5 red, depending on the particular luciferase), and the
release of CO 2 .
Fireflies generally emit in the yellow to green range, as part of a courtship process;
click beetles emit green to orange light; whereas railway worms emit red light,
with green light being emitted on movement.
Dinoflagellates
Much of the brightness that is observed on the surface of the oceans is due to the
bioluminescence of certain species of dinoflagellates, or unicellular algae, and this
bioluminescence accounts for many of the recorded observations that have
described the apparent "phosphorescence" of the sea.
Dinoflagellates are very sensitive to motion induced by ships or fish, and respond
tetrapyrrole
with rapid and brilliant flashes, thus causing the glow that is sometimes seen in
the wake of a ship.
The luciferin in these instances is a tetrapyrrole containing four five-member rings
of one nitrogen and four carbons, and its oxidation , catalyzed by dinoflagellate
luciferase, results in blue-green light centered at about 470 nanometers (1.85 × 10
−5 inches; Figure 2).
Bacteria
Bacterial luciferase catalyzes the reaction of reduced flavin mononucleotide (FMNH 2 )
with O 2 to form a 4a-peroxyflavin derivative that reacts with a
long chain aldehyde leading to the emission of blue-green light (490 nanometers, or 1.93
× 10 −5 inches) and the formation of riboflavin phosphate (FMN; the phosphorylated form
of vitamin B 2 ), H 2 O, and the corresponding fatty acid (Figure).
Luminescent bacteria are found throughout the marine environment, living free, in
symbiosis, or in the gut of marine organisms (including many fish and squid), as well as in
the terrestrial environment as symbionts of nematodes.
fatty acid
Flavin mononucleotide, or riboflavin-5′-phosphate
FMN is a stronger oxidizing agent than NAD
and is particularly useful because it can take
part in both one- and two-electron transfers.
The luciferins believed to be the most
widespread among phyla living in the ocean
have structures based on imidazolopyrazine,
for example, coelenterazine, found in
luminescent coelenterates contains
imidazolopyrazine as its central bicyclic ring
(Figure).
The typical reaction involves the oxidation of
the imidazolopyrazine ring with the emission
of blue light (460–480 nanometers, or 1.81 ×
10 −5 –1.89 × 10 −5 inches), and proceeds
according to a mechanism that is very similar
to that of the oxidation of firefly luciferin.
Among the most commonly studied
imidazolopyrazine-utilizing organisms are
species of Renilla (sea pansy) and Aequorea
(jellyfish) both of which utilize coelenterazine.
The luciferin of a crustacean ( Cypridina or
Vargula ) also is an imidazolopyrazinebased compound related to
coelenterazine. The luciferases of the
luminescent species, however, vary
widely. Recent evidence suggests that
some, and possibly many, marine
luminescent organisms (including the
jellyfish) acquire luciferins via the
ingestion of other luminescent
organisms, which would account for the
widespread distribution of
imidazolopyrazine-based luciferins.
Many luminescent species also have a
binding protein that releases the luciferin
upon Ca ++ uptake, while some have a
fluorescence protein that absorbs and
then emits light at a higher wavelength.
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Many bioluminescent reactions in vitro require cofactors in addition to oxygen, e.g., ATP and Mg2+
for the firefly, Ca2+ for photoproteins (1, 2, 4). In the animal itself (in vivo), there are additional
proteins involved for production and regulation, some called "accessory proteins", examples being
the fatty acid reductase group of enzymes that produce the bacterial luciferin, a long-chain
aldehyde, and there are luciferin-binding proteins in the dinoflagellate and Sea Pansy
bioluminescence systems. Also, there are "antenna proteins" that act to modulate the color of
bioluminescence, the famous Green-fluorescent protein (GFP) in the jellyfish, and the Lumazine
Protein family in some types of bacteria (4). These are named "antenna proteins" by analogy to
proteins of similar function in photosynthesis, except that they act in a reverse sense.
Figure 5. Reaction Schemes for a luciferin/luciferase reaction (A), and for a typical photoprotein
reaction triggered by calcium (B). The reaction product is the light (hv) emitting species, the
protein-bound oxyluciferin or protein-bound coelenteramide.
To date, there are five known distinct chemical classes of luciferins, namely, aldehydes,
benzothiazoles, imidazolopyrazines, tetrapyrroles and flavins. An imidazolopyrazine derivative, aptly
named "coelenterazine", is the luciferin found in coelenterates and many other marine
bioluminescence systems (5, 6).
A membrane-bound luciferase
The small Japanese “firefly squid,” Watasenia scintillans, emits a
bluish luminescence from dermal photogenic organs distributed
along the ventral aspects of the head, mantle, funnel, arms and
eyes.
The brightest light is emitted by a cluster of three tiny organs
located at the tip of each of the fourth pair of arms.
Studies of extracts of the arm organs show that the light is due to
a luciferin–luciferase reaction in which the luciferase is
membrane-bound.
The other components of the reaction are coelenterazine
disulfate (luciferin), ATP, Mg2+, and molecular oxygen.
Based on the results, a reaction scheme is proposed
which involves a rapid base/luciferase-catalyzed
enolization of the keto group of the C-3 carbon of
luciferin, followed by an adenylation of the enol group by
ATP.
The AMP serves as a recognition moiety for docking the
substrate molecule to a luciferase bound to membrane,
after which AMP is cleaved and a four-membered
dioxetanone intermediate is formed by the addition of
molecular oxygen.
The intermediate then spontaneously decomposes to
yield CO2 and coelenteramide disulfate (oxyluciferin) in
the excited state, which serves as the light emitter in the
reaction.
Bioluminescence emission spectrum (uncorrected) of the
Watasenia reaction measured in 0.1 M Tris–HCl buffer, pH
8.26. Light intensity is expressed in RLU;
the wavelength is in nanometers; and the peak intensity is
at 470 nm. The initial concentration of ATP was 1.5 mM.
Dependence of the Watasenia reaction on molecular oxygen.
shows the result of allowing ATP and
homogenate to mix in the absence of
molecular oxygen, which was then followed by
the introduction of air into the mixture. It is
seen that the Watasenia reaction has an
absolute requirement for molecular oxygen.
The small rise in light intensity after the mixing
of ATP and homogenate is presumably due to a
trace amount of air remaining in the apparatus
Biolumnescent organisms
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Adaptations
Bioluminescence is used by living things to hunt prey, defend against predators, find mates, and execute other vital activities.
Defensive Adaptations
Some species luminesce to confuse attackers. Many species of squid, for instance, flash to startle predators, such as fish. With the startled fish caught
off guard, the squid tries to quickly escape.
The vampire squid exhibits a variation of this defensive behavior. Like many deep-sea squid, the vampire squid lacks ink sacs. (Squid that live near the
ocean surface eject dark ink to leave their predators in the dark.) Instead, the vampire squid ejects sticky bioluminescent mucus, which can startle,
confuse, and delay predators, allowing the squid to escape.
Many marine species use a technique called counterillumination to protect themselves. Many predators, such as sharks, hunt from below. They look
above, where sunlight creates shadows beneath prey. Counterillumination is a type of camouflage against this predatory behavior.
Hatchetfish use counterillumination. Hatchetfish have light-producing organs that point downward. They adjust the amount of light coming from
their undersides to match the light coming from above. By adjusting their bioluminescence, they disguise their shadows and become virtually
invisible to predators looking up. Some bioluminescent animals, such as brittle stars, can detach body parts to distract predators. The predator
follows the glowing arm of the brittle star, while the rest of the animal crawls away in the dark. (Brittle stars, like all sea stars, can re-grow their
arms.)
When some animals detach body parts, they detach them on other animals. When threatened, some species of sea cucumber can break off the
luminescent parts of their bodies onto nearby fish. The predator will follow the glow on the fish, while the sea cucumber crawls away.
Biologists think that some species of sharks and whales may take advantage of defensive bioluminescence, even though they are not bioluminescent
themselves. A sperm whale, for instance, may seek out a habitat with large communities of bioluminescent plankton, which are not part of the
whale's diet. As the plankton's predators (fish) approach the plankton, however, their glowing alerts the whale. The whale eats the fish. The plankton
then turn out their lights.
Some insect larvae (nicknamed "glow worms") light up to warn predators that they are toxic. Toads, birds, and other predators know that consuming
these larvae will result in illness and possible death.
Biolumnescent organisms
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Offensive Adaptations
Bioluminescence may be used to lure prey or search for prey.
The most famous predator to use bioluminescence may be the anglerfish, which uses
bioluminescence to lure prey. The anglerfish has a huge head, sharp teeth, and a long, thin, fleshy
growth (called a filament) on the top of its head. On the end of the filament is a ball (called the
esca) that the anglerfish can light up. Smaller fish, curious about the spot of light, swim in for a
closer look. By the time the prey sees the enormous, dark jaws of the anglerfish behind the bright
esca, it may be too late.
Other fish, such as a type of dragonfish called loosejaws, use bioluminescence to search for prey.
Loosejaws have adapted to emit red light; most fish can only see blue light, so loosejaws have an
enormous advantage when they light up a surrounding area. They can see their prey, but their prey
can't see them.
Attraction
Adult fireflies, also called lightning bugs, are bioluminescent. They light up to attract mates.
Although both male and female fireflies can luminesce, in North America most flashing fireflies are
male. The pattern of their flashes tells nearby females what species of firefly they are and that
they're interested in mating.
Biolumnescent organisms
• Other Bioluminescence
• Organisms can luminesce when they are disturbed. Changes in the
environment, such as a drop in salinity, can force bioluminescent algae to
glow, for instance. These living lanterns can be seen as spots of pink or
green in the dark ocean.
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• "Milky seas" are another example of bioluminescence. Unlike
bioluminescent algae, which flash when their environment is disturbed,
milky seas are continuous glows, sometimes bright and large enough to be
visible from satellites in orbit above the Earth.
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• Scientists think milky seas are produced by bioluminescent bacteria on the
surface of the ocean. Millions of bacteria must be present for milky seas to
form, and conditions must be right for the bacteria to have enough
chemicals to light up. Satellite imagery of milky seas have been captured
in tropical waters such as the Indian Ocean.
Biolumnescent organisms
Bioluminescent dinoflagellate ecosystems are rare, mostly forming in
warm-water lagoons with narrow openings to the open sea.
Bioluminescent dinoflagellates gather in these lagoons or bays, and the
narrow opening prevents them from escaping. The whole lagoon can be
illuminated at night. Biologists identified a new bioluminescent
dinoflagellate ecosystem in the Humacao Natural Reserve, Puerto Rico, in
2010.