Download Mrs. Evans: Light at the Bottom of the Deep Dark Ocean

Mrs. Evans: Light at the Bottom of the Deep Dark Ocean
FOCUS QUESTIONS
What colors, if any, are visible down in the deep sea? What is bioluminescence?
LEARNING OBJECTIVES
Students will learn that white light (visible light) is comprised of all colors of the spectrum.
Students will learn that the quantity of light decreases with increasing depth in the ocean.
Students will learn that the quality of light changes with increasing depth.
Students will earn that red light penetrates water the least and that blue light penetrates water the
most.
Students will learn that many ocean organisms are bioluminescent.
Students will learn that bioluminescent light is usually blue.
Students will learn why organisms bioluminesce.
Students will learn about several bioluminescent animals through independent research.
Part I (Reading)
Bioluminescence is simply light produced by a chemical reaction which originates in an organism. It
can be expected anytime and in any region or depth in the sea. Its most common occurrence to the
sailor is in the often brilliantly luminescent bow wave or wake of a surface ship. In these instances
the causal organisms are almost always dinoflagellates, single-cell algae, often numbering many
hundreds per liter. They are mechanically excited to produce light by the ship's passage or even by
the movement of porpoises and smaller fish. Label and color the dinoflagellate to the right, blue.
Next, under “startle” for Bioluminescent Reasons, add the critter dinoflagellate.
On land it is most commonly seen as glowing fungus on wood (called foxfire), or in the few families of
luminous insects. XC if you can tell me one: ___________.
Like the squids and euphausiids (color blue), some bony fishes have
special light producing structures called photophores. These
structures are usually cup shaped and may have elaborate focusing
lenses and reflectors to concentrate and direct the light produced
by the photogenic cells. These photophores are generally controlled
by nerves, and are supplied with blood vessels that deliver oxygen and energy sources needed for
the light producing chemical reaction.
Use a light blue to color the photophores on the next page (A), and yellow for the eye lens (H). The
bars (A2) represent the bioluminescent glow. Color each fish as it is discussed in the text. Note
that the bright flash (A2) of the caudal photophores of the lanternfish is represented as a burst of
light. When coloring the flashlight fish, note that one is “blinking” and has its photophore (A3)
covered by the skin fold (L).
Many mid-water fishes utilize
bioluminescence for purposes
that are often not fully
understood, due to the difficulties in studying
these animals alive. The lanternfishes have
photophores along their ventral surface
(bottom). At night these fishes migrate to the
upper layers of water where they feed on
zooplankton. Seen from below, an unlighted fish
would be clearly silhouetted against the moonlit
water surface and thus be vulnerable to attack
from below by predators using visual cues.
Write in the lanternfish below (Reasons for
Bioluminescence) after the appropriate
explanation. Lanternfishes use their ventral photophores to erase
this silhouette and blend with the moonlit upper waters. This
phenomenon is known as counterlighting and occurs in a number of
fishes, squids and crustaceans.
The photophores of most squids can be turned on or off and their
intensity varied by direct nervous control. Some deep sea squids that
form schools probably use their bioluminescence to maintain contact
with members of their species (possibly mating clues/write this
species in the appropriate area for Reasons for Biolum). Color the
firefly squid grey and the photophores (E) blue.
Mating behavior in a pair of
Green Lanternsharks
(Etmopterus virens). Before
mating, the male (in
foreground) ritualistically
bites the trailing edge of the
female's pectoral fins ('love
nips') in a tender gesture
only sharks would
understand. The pattern of
photophores is species- and
gender-specific, allowing
Green Laternsharks to
recognize others of their
kind and to co-ordinate
schooling and mating
behaviors in the blackness
of the deep-sea.
The caudal (rear) photophores of many lanternfishes are used in
evading predators. Seeing a threat, the fish emits a bright flash of
light from the caudal photophores and, at the same time, swims
rapidly away. The predator is startled and confused, and focuses its
attention on the spot where the flash occurred giving the lanternfish an opportunity to escape.
The hatchetfish uses its ventral photophores for protective counterlighting (write him in the
appropriate spot for Reasons for Biolum. It also possesses unique upward facing eyes equipped with
yellow lenses. The lenses serve as filters that allow the fish to distinguish the narrow color range
of normal background light. By looking up into moonlit water, the hatchetfish can discern potential
prey animals that are using photophores in counter lighting behavior, thus capitalizing on the
defense mechanism of its prey. From our adaptations lecture, write what his eyes are called when
they are “upward facing” next to the picture of the hatchetfish.
The deep water predatory stomiatid attracts potential prey with a lure equipped with a photophore
located on the fish’s chin whiskers; what is another name for these? Label it on the fish. Males are
smaller and have a photophore beneath their eyes; the female is the only one that possesses this
“whisker”. This photophore probably aids recognition between male and females in their dark
environment. Write this in under Reasons for Biolum.
The small (7-8cm) shallow water flashlight fish bears photophores that are among the brightest and
largest found in any bioluminescent organism. However, the blue-green light emitted from these
photophores is not produced by the fish themselves, but rather by billions of luminescent bacteria
harbored within the photophore by the host fish. The fish’s blood stream keeps the microscopic
inhabitants of this bacterial photophore supplied with nutrients and
oxygen. The bacteria glow in a special pouch that is lined
with dark skin arranged in such a fashion as to prevent
the light from blinding the fish. As a control mechanism,
the fish posses a fold of skin that can be raised over the
pouch to cover the photophore and essential “turn off”
the light. Flashlight fish remain hidden in the coral reef
by day and on moonlit nights. On darks nights groups of
from a few to sixty fish congregate near the surface. The combined glow
of their bacterial photophores attracts their small zooplanktonic prey. If
a larger potential predator is attracted to the light, the flashlight fish executes a strategic
defense response known as “blink and run.” The fish swims in one direction with its light “on,” then
covers the light and swims in a different direction (up to 75 times a minute). This effect of
“blinking and running” is to confuse the predator and permit the escape of the small fish.
Key Points
-Bioluminescence is light produced by a chemical reaction which originates in an organism.
-Bioluminescence is a primarily marine phenomenon. In contrast, bioluminescence is essentially absent in fresh
water.
-Bioluminescence has evolved many times in the sea as evidenced by the several distinct chemical mechanisms
by which light is emitted and the large number of only distantly related taxonomic groups that have many
bioluminescent members.
-Bioluminescence is not the same as "fluorescence" or "phosphorescence". In fluorescence, energy from a
source of light is absorbed and re-emitted as another photon. In bioluminescence or chemoluminescence the
excitation energy is supplied by a chemical reaction rather than from a source of light.
-At least two chemicals are required. The one which produces the light is generically called a "luciferin" and
the one that drives or catalyzes the reaction is called a "luciferase."
-Almost all marine bioluminescence is blue in color, for two related reasons. A notable exception to this "rule"
is Malacosteid family of fishes (known as Loosejaws), which produce red light and are able to see this light
when other organisms can not.
Because it is found in so many different types of
organisms, bioluminescence must serve many
functions in the ocean. However many of the
functions are still unknown, because experimental
evidence has been gathered for only a few of the
many proposed roles. Luminescence can serve two
or more purposes, both offensive and defensive,
within a single organism. Here we summarize the
range of functions that have been proposed for
marine bioluminescence.
Light in the bottom of the Deep Dark Ocean
(M&M Lab) Background Information:
If you were able to combine all of the world’s
ocean basins and stir them together with a spoon,
the average temperature of the water would be 4°C, the average depth would be about 14,000 feet,
and the average light level would be zero. The bulk of our oceans are comprised of deep sea habitats
that exist in very little to no light.
With regard to light level, the ocean has been divided into three zones based on depth and light
level. The specific depths of these zones will vary based on a number of physical parameters, but
the following three divisions can be used when talking about light levels in ocean waters. The upper
200 meters of the ocean is termed the photic zone. This zone is penetrated by sunlight and plants
thrive. The zone between 200 meters and 1000 meters is known as the “twilight” zone; in this zone
the intensity of light dissipates as depth increases and at the lower depths, light penetration
becomes minimal. The aphotic zone, or “midnight” zone, exists in depths below 1000 meters. Sunlight
does not penetrate to these depths and the zone is bathed in darkness.
Since a bulk of the ocean contains vast regions where light levels are low to nonexistent, numerous
species that inhabit these deeper waters produce their own light. This biological process is termed
what:______________________.
As you travel from surface waters to deeper waters, the quantity of light changes; it decreases
with depth. The quality of light also varies with depth. Sunlight contains all
of the colors of the visible spectrum (red, orange, yellow, green, blue and
violet). These colors combined together appear white. Red light has the
longest wavelength and therefore the least amount of energy in the visible
spectrum. Violet light has the shortest wavelength and therefore the
highest amount of energy in the visible spectrum. The wavelength decreases
and the energy increases as you move from red to violet light across the
spectrum in the following order: red, orange, yellow, green, blue and violet.
Red light is quickly filtered from water as depth increases. As the
wavelength of light increases from red light to blue light, so does its ability
to penetrate water; blue light penetrates best. Green light is second, yellow
light is third followed by orange light and red light. The exception to the
rule is violet light. Although it has the shortest wavelength and the highest
energy, violet light is also quickly filtered from water; the small wavelength
of light is easily scatted by particles in the water.
All objects that are not transparent or translucent either absorb or reflect nearly all of the light
that strikes them. When struck by white light (containing all colors), a red fish reflects red light
and absorbs all other colors. Likewise, grass reflects green light and absorbs all other colors. White
objects appear white because they reflect all colors of light in the visible spectrum. Black objects
appear black because they absorb all colors of light. Now consider that red fish. If a red fish is
swimming at the surface of the ocean, it appears red because it reflects red light. Can you see a red
fish swimming at 100 meters? At this depth the red fish is difficult, if not impossible to see, and
appears blackish because there is no red light to reflect at that depth and the fish absorbs all
other wavelengths of color.
In the twilight zone, there are numerous animals that are black or red. At depth, these organisms
are not visible. The black animals absorb all colors of light available and the red animals appear black
as well; there is no red light to reflect and their bodies absorb all other available wavelengths of
light. Thus red and black animals predominate. Since the color blue penetrates best in water, there
simply are not that many blue animals in the midwater regions of the ocean; their entire bodies
would reflect the blue light and they would be highly visible to predators.
Animals that seek to produce something visible to other organisms have taken advantage of the
penetration of blue light in water. Many ocean animals, especially those living in the twilight and midnight zones, are bioluminescent and can produce their own light. Most bioluminescence, although not
all, produces blue light. This now makes sense. An animal producing red light in deep water would produce light that is not visible. Blue light, in the form of bioluminescence, is visible at depth.
Bioluminescence has evolved in many different species and this suggests its importance to survival in
the deep sea.
Prelab questions:
1. What is the average temperature of the ocean?
2. Describe the three ocean “zones.”
3. Why is red light quickly filtered from water as depth increases?
4. What two colors penetrate water best?
5. Why does a red fish “appear” red when struck by white light?
6. Why does a black fish “appear” black and a white fish “appear”
7. Why is it advantageous for deep sea fish to be black or red?
8. Why are there not that many blue animals in the “twilight zone” of the ocean?
9. Why would some deep sea creatures emit a red light?
Light in the bottom of the Deep Dark Ocean
1. Get out one piece of black construction paper, one set of Deep Sea Diving Goggles, and one “M&M
set” for each pair. (The black piece of paper represents the darkness of the deep sea.)
2. Spread your M&Ms out over the black piece of paper.
3. Place one of the 3 layers of blue report covers over your eyes and while looking through the blue
layer, observe which colors of M&Ms are readily visible.
___________________________________________Each lab partner needs to observe this.
4. Add an additional report cover layer (total of two layers) and repeat your observations.
__________________________________________________
5. Add your last layer. _________________________________________ Note: Using the blue
report covers allows you to see how colors appear in deeper water. The blue covers filter out other
colors of the spectrum with increasing efficiency as additional layers are used. Water, likewise, with
increasing depth selectively filters out all other colors of the spectrum with the exception of blue.
Did you observe that the color black disappears first, followed by red, then orange, and yellow?
_yes/no__
6. Why again are there are so many red animals living in the twilight zone?
__________________________________________________________________________
__________________________________________________________________________
7. Why do you think most bioluminescence produces blue light and not some other color?
__________________________________________________________________________
__________________________________________________________________________
Part III Chemiluminescence
This reaction involves two basic ingredients, an oxidizing agent (hydrogen peroxide), and the
reactant solution (luminol). When the hydrogen peroxide is mixed with the luminol solution, the
electrons get excited, producing photons of light. Even heat, which is generally associated with the
light of most kinds, is noticeably absent. Light sticks, which all of us are familiar with contain
chemicals in two compartments separated by a divider. When the divider is broken and the
chemicals mix, chemiluminescence results. The greater the rate of reaction, the greater the
amount of light produced.
Mrs. Garbiel (or her TA’s) has already done this procedure but FYI:
1. Empty one vial of reagent A (Luminol) in a beaker and thoroughly dissolve it in 500 mL of tap
water. This should be prepared shorlty before use as Luminol begins to deteriorate when in solution.
2. In another beaker, measure 30 mL using a graduated cylinder of the stock Luminol Activator
solution and dilute it with 470 mL of water to make 500 mL.
This is where YOU begin.
3. Measure 5 or 10 mL (Please circle which one Mrs. Garbiel said to use) of each of the above
two solutions into two clean flasks, graduated cylinders or test tubes.
4. Darken the room as much as possible.
5. Pour the two solutions simultaneously through a funnel into your tube.
6. As the two chemicals interact, light is released.
What was the color of the solutions before the reaction? ______________
What was the color of the solutions after the reaction? _______________
Part IV Your own Glowsticks. Write down Mrs. Evans’s procedure:
Part V
OPTION 1: Research another bioluminescent organism and write a 1 page report or create a poster
describing its habitat, behavior and mechanism of bioluminescence. Some examples:
Anglerfish
Bristlemouth
Fangtooth
Filetail catshark
Snailfish
Midwater shrimp
Sixgill shark
Giant ostracod
Giant red mysid
Gulper eel
Hatchetfish
Lanternfish
Eelpout
Blackdragon
Hagfish
Viperfish
Shining
tubeshoulder
Snipe eel
Ratfish
Squat lobster
Mrs. Garbiel: Marine Biology Spring 2010