The Mesopelagic Zone Refers To The Ocean Depths In Which There Is


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The mesopelagic zone refers to the ocean depths in which there is

enough light to support plant growth.

no light at all.

dim light, but not enough for plant growth.

enough light for primary production by bacteria.

dim light, but enough to support only some hardy plants.


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Where is the main thermocline located?

In the mesopelagic.

Above the mesopelagic.

Below the mesopelagic.

It varies since the thermocline disappears in the tropics.

It varies since the thermocline moves up and down in the water column depending on the amount of oxygen.


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Photophores are

specialized eyes.

buoyancy-regulating organs.

specialized jaws.

light-sensitive organs that lack the lens of true eyes.

light-producing organs.


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Which of the following is not true regarding the deep-scattering layer (DSL)?

Its position rises at night and moves down during the day.

It is comprised of fish, shrimp, squids and jellyfish.

It is found at depths of 300-500 meters.

It was discovered by sonar.

Its position is deeper on nights with a new moon.


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The tubular eyes of some mid-water animals are adapted for

increasing the field of vision.

producing light.

seeing in the complete absence of light.

sensing changes in depth.

sensing changes in salinity.


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The presence of bioluminescent organs on the underside of mid-water fishes is involved in


enlargement of silhouette.

creating a transparency effect.

cryptic coloration.



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Deep-sea pelagic fishes are characterized by all of the following except

small eyes.

absent or reduced swim bladder.

red color.

flabby muscles.

large mouth and teeth.


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Which of the following is an important feeding adaptation among deep-sea fishes?

Migration to shallower water to feed

Feeding on males, hence the term “male parasitism”

Ability to eat prey bigger than themselves

Strong muscles that allow them to move fast to catch any available prey

Absence of a stomach


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Pheromones are special chemicals that are used to

digest food.

attract mates.

catch prey.

transport oxygen.

produce bioluminescence.


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The energy source for the bacteria that thrive around deep-sea hydrothermal vents is

hydrogen sulfide.


heat from the hydrothermal vents.


tube-worm tissues.


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The major advantage that deep-sea benthic animals have over pelagic ones is that their food

is easier to digest.

falls to the bottom and stays in one place, thus being available for a longer time.

gets to be eaten before it gets to pelagic animals.

gets less decayed by bacteria

produces less detritus.


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A shrimp that occurs in large numbers around deep-sea hydrothermal vents does not have eyes. Light-sensitive cells on the top of the body, however, appear to be used to detect faint light from

bioluminescent predators.

the surface.

faint glow around vents.

bioluminescent prey.



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An unknown fish has been brought to the student to examine. This fish is black, relatively small with small eyes and weak, flabby muscles. This fish is most likely from which zone?

Mesopelagic (vertical migratory)

Mesopelagic (vertical non-migrator)


Deep pelagic

Deep-sea benthic


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Traditional fisheries are those that

have their catches routinely recorded.

catch shellfish, not finfish.

do not use boats.

use relatively simple gear and methods.

do not sell their catches to the general public.


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Most marine food resources are taken from

coral reefs.

the continental shelf.

open waters off the continental shelf.


mariculture ponds.


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By definition, pelagic catches are those that are harvested from

the open water.

the bottom.


waters where primary production is increased by upwelling.

the continental shelf.


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Trawls are nets that

surround and trap fish.

float on the surface.

are allowed to drift along the surface.

are placed along the bottom to trap passing fishes.

are dragged along the bottom or through the water column.


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The maximum sustainable yield is best defined as the

highest catch that can be taken without overfishing.

maximum fishing effort allowed after overfishing is reached.

highest catch that will pay the minimum cost of the fishing effort.

minimum catch that will still allow the population to grow.

the annual size of the catch that will balance natural death and predation.


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Continued catches above the maximum sustainable yield

can be increased to prevent overfishing.

will result in underutilization.

will result in a decrease of fishing effort.

must be decreased in order to decrease population size.

will result in overfishing.


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Which of the following best describes commercial fisheries around the world?

Most have been affected by overfishing.

About 20% have been affected by overfishing.

All have been affected by overfishing.

All have been affected by overfishing but none have been exhausted.

None in the Southern Hemisphere have been affected by overfishing.


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The farming of salmon includes all the following problems except

higher levels of contaminants in farmed fish tissue.

pollution released into environment.

it is more expensive.

it threatens genetic identity of wild salmon.

it increases parasites


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“By-catch” is the name given to

unwanted species that are caught while fishing.

species caught for industrial purposes.

krill and other shellfish.

species raised in fish farms.

species caught as part of traditional fisheries.


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Releasing farmed salmon fry to grow at sea and harvesting them when they return to the river where they were released is called

open mariculture.

closed mariculture.

salmon ranching.

traditional salmon runs.

intensive mariculture.


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Desalination plants

extract minerals for industrial use from seawater.

convert seawater into fresh water.

extract table salt from seawater.

convert seawater into brackish water for industrial uses.

extract oil from seawater.


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Successful pharmaceutical uses for marine organisms include all of the following except

red seaweed extract used for weight gain.

sponge extract used as anti-inflammatory.

squalamine from sharks used to treat cancer.

bryostating from bryozoans used to treat cancer.

horseshoe crab blood used to test vaccines from contamination.