Question
Read the passage below. Then, answer the questions by choosing the BEST responses.
Passage 3 of 3
Bioluminescent Organisms: Meet the living nightlights of our world
Marcia Amidon Lusted
2022
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Medium
In this article, the author explores bioluminescent organisms.
Fireflies dot the twilight sky like sparks above a verdant meadow, languid jellyfish glow softly as they glide slowly through the ocean’s depths, and tiny algae shimmer like handfuls of glitter on the surface of inky black water on a dark night. What gives these creatures the ability to diffuse their own light, and what purpose does it serve?
The scientific answer to that question is found in a chemical reaction called bioluminescence. This reaction creates a light within the body of certain organisms, and its purpose can be one of several: to see or attract prey, to entice a mate, or to communicate. These functions contribute to one essential concern for all living things: survival.
Bioluminescent organisms are largely found in the ocean; from the deepest seabed floor to the water’s surface, they are present throughout the entire water column. The near-total darkness of the deep ocean makes bioluminescence necessary for hunting and communicating. Luminescent organisms in the ocean include squid, jellyfish, bacteria, algae, worms, crustaceans, sea stars, fish, and even sharks. While there are fewer bioluminescent organisms on land, there are several insects that possess the capability to illuminate, including fireflies, worms, millipedes, larvae, and spiders. Interestingly, there are few bioluminescent plants; although, some species of mushrooms and fungi have the ability to emit light.
Bioluminescence requires specific elements to interact and form the necessary chemical reaction, which takes place within the organism’s cells. In order to generate bioluminescence, an organism must possess the pigment luciferin, a molecule that produces light by reacting with oxygen. Some organisms also have the enzyme luciferase, which speeds up the luciferin-oxygen reaction. Other organisms are able to emit light with the assistance of light-producing bacteria occupying a special organ called the “light organ.”
The Hawaiian bobtail squid has a symbiotic relationship with the bacteria that they host. This nocturnal squid lives primarily in shallow water, so it needs bioluminescence to camouflage itself against the starlit night sky. Seen from below, a solid black shadow is much more obvious than a shape that mimics a starry sky. The bobtail squid relies on specific, bioluminescent bacteria that inhabit the squid’s light organ and begin to glow when it gets dark. When morning comes, the squid expels 95% of the bacteria from its light organ; the squid keeps and nourishes the other 5% so their number will increase throughout the day. By the time darkness descends again, there are enough bacteria present in the squid’s light organ to camouflage it once more.
Bioluminescence manifests in a variety of colors, but the majority of the bioluminescence produced in the ocean appears blue-green in color. Light waves move differently in water, and blue-green light waves are shorter than other colors; they can travel and be seen more easily in deep water. It is almost impossible to perceive the color red in the ocean, thus many fish are red in color because it makes them nearly invisible to other fish. One exception is the dragonfish, which emits red bioluminescence and detects red light waves; they use this ability to discern fish with red markings or coloration upon which they can prey. It also proves to be an effective way to communicate with other dragonfish.
In addition to using bioluminescence for camouflage — like the bobtail squid — some organisms utilize bioluminescence as a defense. For instance, jellyfish’s light is activated by touch. A potential predator may be startled by the sudden glow after grazing a jellyfish and leave it alone. The light can also attract other animals that prey on jellyfish’s predators. Jellyfish utilize their light to warn fellow jellyfish about predators in the vicinity. Dinoflagellates, which are a type of algae called “fire algae,” brandish their light to scare off predators. When this occurs, they create a beautiful blue glow on the water’s surface.
Beyond defending themselves, organisms also utilize bioluminescence to attract prey. One of the most startling examples of this is the angler fish, which lives deep in the ocean. The females possess a fleshy bulb that protrudes out of the dorsal fin, resembling a lantern on the end of a pole. The bulb contains light-emitting bacteria that trade their light for a safe habitat. The glowing bulb acts as a lure to attract prey into the sharp teeth of the angler fish.
For some organisms, bioluminescence can attract a mate. Fireflies flicker to attract mates as well as prey, and males and females have different flashing patterns to distinguish them. Some fireflies can even synchronize their flashes, which is known as simultaneous bioluminescence. This usually occurs in groups of male fireflies, called leks, that flash their lights at the same time to attract females.
Humans have a history of adapting bioluminescence for their own purposes. Indigenous peoples in Indonesia once used bioluminescent fungi to find their way in the dark. Before the invention of electrical lights, miners in need of safety lamps captured fireflies in jars to help navigate in the pitch black of underground tunnels.
For scientists, the most exciting applications for bioluminescence are still being developed. Certain bioluminescent bacteria can be utilized to monitor water quality. When these bacteria encounter a form of pollution, their glow dims, signaling potential water contamination. With the genes responsible for certain fungi’s glow, scientists are researching ways to engineer trees that glow at night, eliminating the need for electric street lamps. Glowing house plants could also reduce the need for electric lighting in homes and businesses.
Bioluminescence is one of the wonders of the natural world that benefits both the organisms that create it and the humans who can harness it. Even with all of the exciting potential that bioluminescence holds, one of its greatest aspects remains the simple beauty of a sparkling firefly-lit night, the surface of a bay glowing with blue algae, or a jellyfish floating ethereally through the blue ocean.
Text: "Bioluminescent Organisms: Meet the living nightlights of our world" by Marcia Amidon Lusted. Copyright © 2022 by CommonLit, Inc. This text is licensed under CC BY-NC-SA 4.0.
Image: "Untitled" by Marat Gilyadzinov is licensed under CC0.
Assessment Questions
1
…
23
24
25
26
27
…
35
24 out of 35 Answered
Question 25
Which quotation indicates the meaning of "languid" in paragraph 1?
A. "glow softly"
B. "glide slowly"
C. "ocean's depths"
D. "handfuls of glitter"
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Next
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Passage 3 of 3
Bioluminescent Organisms: Meet the living nightlights of our world
Marcia Amidon Lusted
2022
Font Size
Medium
In this article, the author explores bioluminescent organisms.
Fireflies dot the twilight sky like sparks above a verdant meadow, languid jellyfish glow softly as they glide slowly through the ocean’s depths, and tiny algae shimmer like handfuls of glitter on the surface of inky black water on a dark night. What gives these creatures the ability to diffuse their own light, and what purpose does it serve?
The scientific answer to that question is found in a chemical reaction called bioluminescence. This reaction creates a light within the body of certain organisms, and its purpose can be one of several: to see or attract prey, to entice a mate, or to communicate. These functions contribute to one essential concern for all living things: survival.
Bioluminescent organisms are largely found in the ocean; from the deepest seabed floor to the water’s surface, they are present throughout the entire water column. The near-total darkness of the deep ocean makes bioluminescence necessary for hunting and communicating. Luminescent organisms in the ocean include squid, jellyfish, bacteria, algae, worms, crustaceans, sea stars, fish, and even sharks. While there are fewer bioluminescent organisms on land, there are several insects that possess the capability to illuminate, including fireflies, worms, millipedes, larvae, and spiders. Interestingly, there are few bioluminescent plants; although, some species of mushrooms and fungi have the ability to emit light.
Bioluminescence requires specific elements to interact and form the necessary chemical reaction, which takes place within the organism’s cells. In order to generate bioluminescence, an organism must possess the pigment luciferin, a molecule that produces light by reacting with oxygen. Some organisms also have the enzyme luciferase, which speeds up the luciferin-oxygen reaction. Other organisms are able to emit light with the assistance of light-producing bacteria occupying a special organ called the “light organ.”
The Hawaiian bobtail squid has a symbiotic relationship with the bacteria that they host. This nocturnal squid lives primarily in shallow water, so it needs bioluminescence to camouflage itself against the starlit night sky. Seen from below, a solid black shadow is much more obvious than a shape that mimics a starry sky. The bobtail squid relies on specific, bioluminescent bacteria that inhabit the squid’s light organ and begin to glow when it gets dark. When morning comes, the squid expels 95% of the bacteria from its light organ; the squid keeps and nourishes the other 5% so their number will increase throughout the day. By the time darkness descends again, there are enough bacteria present in the squid’s light organ to camouflage it once more.
Bioluminescence manifests in a variety of colors, but the majority of the bioluminescence produced in the ocean appears blue-green in color. Light waves move differently in water, and blue-green light waves are shorter than other colors; they can travel and be seen more easily in deep water. It is almost impossible to perceive the color red in the ocean, thus many fish are red in color because it makes them nearly invisible to other fish. One exception is the dragonfish, which emits red bioluminescence and detects red light waves; they use this ability to discern fish with red markings or coloration upon which they can prey. It also proves to be an effective way to communicate with other dragonfish.
In addition to using bioluminescence for camouflage — like the bobtail squid — some organisms utilize bioluminescence as a defense. For instance, jellyfish’s light is activated by touch. A potential predator may be startled by the sudden glow after grazing a jellyfish and leave it alone. The light can also attract other animals that prey on jellyfish’s predators. Jellyfish utilize their light to warn fellow jellyfish about predators in the vicinity. Dinoflagellates, which are a type of algae called “fire algae,” brandish their light to scare off predators. When this occurs, they create a beautiful blue glow on the water’s surface.
Beyond defending themselves, organisms also utilize bioluminescence to attract prey. One of the most startling examples of this is the angler fish, which lives deep in the ocean. The females possess a fleshy bulb that protrudes out of the dorsal fin, resembling a lantern on the end of a pole. The bulb contains light-emitting bacteria that trade their light for a safe habitat. The glowing bulb acts as a lure to attract prey into the sharp teeth of the angler fish.
For some organisms, bioluminescence can attract a mate. Fireflies flicker to attract mates as well as prey, and males and females have different flashing patterns to distinguish them. Some fireflies can even synchronize their flashes, which is known as simultaneous bioluminescence. This usually occurs in groups of male fireflies, called leks, that flash their lights at the same time to attract females.
Humans have a history of adapting bioluminescence for their own purposes. Indigenous peoples in Indonesia once used bioluminescent fungi to find their way in the dark. Before the invention of electrical lights, miners in need of safety lamps captured fireflies in jars to help navigate in the pitch black of underground tunnels.
For scientists, the most exciting applications for bioluminescence are still being developed. Certain bioluminescent bacteria can be utilized to monitor water quality. When these bacteria encounter a form of pollution, their glow dims, signaling potential water contamination. With the genes responsible for certain fungi’s glow, scientists are researching ways to engineer trees that glow at night, eliminating the need for electric street lamps. Glowing house plants could also reduce the need for electric lighting in homes and businesses.
Bioluminescence is one of the wonders of the natural world that benefits both the organisms that create it and the humans who can harness it. Even with all of the exciting potential that bioluminescence holds, one of its greatest aspects remains the simple beauty of a sparkling firefly-lit night, the surface of a bay glowing with blue algae, or a jellyfish floating ethereally through the blue ocean.
Text: "Bioluminescent Organisms: Meet the living nightlights of our world" by Marcia Amidon Lusted. Copyright © 2022 by CommonLit, Inc. This text is licensed under CC BY-NC-SA 4.0.
Image: "Untitled" by Marat Gilyadzinov is licensed under CC0.
Assessment Questions
1
…
23
24
25
26
27
…
35
24 out of 35 Answered
Question 25
Which quotation indicates the meaning of "languid" in paragraph 1?
A. "glow softly"
B. "glide slowly"
C. "ocean's depths"
D. "handfuls of glitter"
Back
Next
Terms of Use
Answers
GPT-4o mini
The quotation that indicates the meaning of "languid" in paragraph 1 is:
**B. "glide slowly"**
The term "languid" suggests a state of weakness or fatigue, often associated with a slow, relaxed movement, which aligns with "glide slowly."
**B. "glide slowly"**
The term "languid" suggests a state of weakness or fatigue, often associated with a slow, relaxed movement, which aligns with "glide slowly."