Deck 14: The Benthos: Living on the Sea Floor

Question 1

Where benthic, burrowing detritus feeders are found in great numbers, the sediments are likely to have a high-organic content.

Answer 1

True

Question 2

Animals that burrow into the seafloor are members of the epifauna.

Answer 2

False

Question 3

There are more kinds of benthic animals than there are pelagic animals.

Answer 3

True

Question 4

The green seaweeds are the largest of the marine algae; they are also known as kelps.

Question 5

Species of epifauna are less abundant than species of infauna.

Question 6

Cold seeps and salt seeps have no associated animal communities.

Question 7

Bacteria are a valuable source of protein for other marine organisms.

Question 8

Human activities are among the greatest threats to the world's coral reefs.

Question 9

Epifauna live on the surface of the marine sediments.

Question 10

The stem is the part of seaweeds that connects the blade to the holdfast.

Question 11

Numbers of organisms and diversity of species decrease as depth increases.

Question 12

More than 75% of the benthic animals belong to the epifauna.

Question 13

Episodes of coral bleaching have become more frequent and more severe in the last twenty years.

Question 14

Sessile organisms live attached to the seafloor.

Question 15

Eel grass is a marine plant.

Question 16

Large benthic algae (seaweeds) have holdfasts that absorb nutrients in the same way roots absorb nutrients for land plants.

Question 17

Algae form the base of the trophic system for hydrothermal vent communities.

Question 18

Large algae (seaweeds) growing attached to the bottom create a specialized environment for other marine organisms.

Question 19

Coral bleaching is produced by the invasion of crown of thorns starfish (Acanthaster).

Question 20

Few algae are found growing on gravel and sand beaches.

Question 21

Coral bleaching results in

A) the expulsion of zooxanthellae from corals.
B) the weakening of corals and higher levels of disease.
C) the death of many corals.
D) All of these are correct.
E) None of these are correct.

Question 22

Animals and algae living attached to the bottom are members of the

A) phytoplankton.
B) zooplankton.
C) nekton.
D) benthos.
E) All of these are correct.

Question 23

Intertidal zonation on a rocky beach is primarily controlled by the

A) type of bottom.
B) prey-predator relationships.
C) salinity, temperature, and pressure.
D) amount of time an organism spends out of water.
E) organisms's metabolism.

Question 24

The first trophic level in a hydrothermal vent community is

A) seriously polluted.
B) dependent on bacteria and their ability to use hydrogen sulfide.
C) dependent on organic material drifting down from the surface.
D) provided by larvae drifting in deep-sea currents.
E) made up of clams and tube worms.

Question 25

Water must be warmer than ______ to support a reef of corals with zooxanthellae.

A) 15
B) 18
C) 23
D) 25
E) 30

Question 26

Which organisms burrow into the deep-ocean muds in a process called bioturbation?

A) Starfish
B) Sponges
C) Sea cucumbers
D) Clams
E) Sea urchins

Question 27

Coral reefs are formed by

A) coral polyps and calcareous algae.
B) shells and worm tubes.
C) volcanic action and subsidence.
D) coral polyps and calcareous algae and shells and worm tubes.
E) coral polyps and calcareous algae, shells and worm tubes, and volcanic action and subsidence.

Question 28

The benthic zone is considered the seafloor while the pelagic zone is the seawater.

Question 29

Blades are the photosynthetic organ of seaweed.

Question 30

An individual coral animal is known as a/an

A) zooxanthella.
B) sponge.
C) polyp.
D) alga.
E) zooxanthella or polyp.

Question 31

Zooxanthellae are

A) dinoflagellates living in tropical corals.
B) copepods feeding on diatoms and dinoflagellates.
C) bacteria associated with hydrothermal vents.
D) the same thing as krill.
E) members of the meroplankton.

Question 32

Chemosynthetic communities are found associated with

A) hydrothermal vents.
B) oil and gas seeps.
C) salt brine seeps.
D) All of these are correct.
E) None of these are correct.

Question 33

The symbiotic relationship between coral polyps and zooxanthellae is an example of

A) commensalism.
B) mutualism.
C) parasitism.
D) All of these are correct.
E) None of these are correct.

Question 34

Marine algae are found in which sequence from sea surface to deeper water?

A) green, brown, red
B) red, brown, green
C) green, red, brown
D) brown, green, red
E) red, green, brown

Question 35

Most animals that live within the sand and mud feed on detritus.

Question 36

The base of the food chain in hydrothermal vent communities is phytoplankton.

Question 37

Animals that live on bits and pieces of organic material washed in from the sea or off the land are called

A) filter feeders.
B) herbivores.
C) deposit feeders.
D) detritus feeders.
E) grazers.

Question 38

The holdfast that attaches seaweed to rocks or shells is a root.

Question 39

Intertidal communities have low productivity because of high wave activity.

Question 40

Seafloor organisms modify their habitat and create new habitats for other organisms.

Question 41

Benthic microalgae are best adapted to living

A) in the rocky intertidal zone
B) below the euphotic zone.
C) within shallow sandy or muddy environments.
D) in tidepools.

Question 42

A close relationship between unrelated organisms in which one organism benefits and the other is unaffected is known as

A) symbiosis.
B) commensalism.
C) parasitism.
D) mutualism.
E) symbiosis and commensalism.

Question 43

In Washington State, the ________________ acts as a keystone predator; when removed, biodiversity ________________ .

A) sea star; decreases
B) sea otter; decreases
C) mussel; increases
D) sea star; increases
E) mussel, decreases

Question 44

Bacteria are not a major source of protein for infaunal organisms.

Question 45

Common deep-sea vent communities include all of the following except

A) filter-feeding clams and mussels.
B) fish.
C) crabs.
D) deep-water corals.
E) tubeworms.

Question 46

The disruption of sediment by feeding and burrowing organisms is called

A) tilling.
B) bioturbation.
C) sediment exchange.
D) respiration.

Question 47

Macroalgae/seaweeds can be best differentiated from true plants because macroalgae/seaweeds

A) are photosynthetic.
B) are prokaryotic.
C) have no true roots, leaves, or stems.
D) have no chlorophyll.
E) are mostly unicellular.

Question 48

Marine vascular flowering plants include all of the following except

A) mangroves.
B) kelps.
C) seagrasses.
D) cord grass.
E) surf grass.

Question 49

Zooxanthellae are highly specialized cyanobacteria that form a symbiotic relationship with corals.

Question 50

One adaptation of many intertidal invertebrates is to develop a rounded profile to minimize resistance to breaking waves.

Question 51

The stable conditions of deep benthic environments seem to favor ________________ infaunal organisms.

A) carnivorous
B) surface-dwelling
C) deposit-feeding
D) symbiotic

Question 52

Symbiosis is defined as

A) the grouping of organisms according to their ability to cope with exposure and water loss.
B) a relationship between animals living on a mud flat and their environment.
C) the relationship between herbivores and the algae that they graze upon.
D) a close intimate relationship between two dissimilar organisms.
E) None of these are correct.

Question 53

CLOD or Coral Lethal Orange Disease

A) attacks and kills coral polyps.
B) kills zooxanthellae causing bleaching.
C) kills algae that cement sand debris to form a hard surface reef.
D) kills clams and crabs on coral reefs.
E) attacks and kills coral polyps, kills zooxanthellae causing bleaching, and kills algae that cement sand debris to form a hard surface reef.

Question 54

Macroalgae take advantage of surface/volume ratios by exposing wide, flattened blades to sunlight and nutrient-rich water.

Question 55

Brown algae include

A) Ulva,or sea lettuce.
B) dinoflagellates.
C) kelp.
D) Porphyra.

Question 56

Benthic organisms living in the bottoms of trenches live in the ________ zone.

A) bathyal
B) sublittoral
C) abyssal
D) hadal
E) supralittoral

Question 57

Vent communities have been discovered making use of many energy sources, including all of the following except

A) hydrothermal vents.
B) methane seeps.
C) salt seeps.
D) radioactive seeps.
E) cold seeps.

Question 58

The size and shape of sediment particles influences both the ______________, or amount of space between particles, and _______________ the flow of water and gases.

A) porosity; permeability
B) porosity; rugosity
C) permeability; inundation
D) exchange; permeability

Question 59

A typical kelp forest shows strong vertical zonation from the well-lit surface to the bottom, including (from surface to bottom) the following zones:

A) Understory, Canopy, Algae Turf
B) Canopy, Understory, Algae Turf
C) Canopy, Understory, Intertidal
D) Inshore, Kelp Canopy, Offshore

Question 60

Mangrove trees grow in swampy salt water along

A) temperate coasts.
B) crests of coral reefs.
C) coasts with heavy surf.
D) areas of extreme evaporation and high salinity.
E) tropical coasts.