Deck 14: The Benthos: Living on the Sea Floor

Question 1

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

Answer 1

False

Question 2

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

Answer 2

True

Question 3

Epifauna live on the surface of the marine sediments.

Answer 3

True

Question 4

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

Question 5

Cold seeps and salt seeps have no associated animal communities.

Question 6

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

Question 7

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

Question 8

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

Question 9

Sessile organisms live attached to the seafloor.

Question 10

Eel grass is a marine plant.

Question 11

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

Question 12

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

Question 13

Species of epifauna are less abundant than species of infauna.

Question 14

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

Question 15

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

Question 16

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

Question 17

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

Question 18

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

Question 19

Episodes of coral bleaching have become more frequent and more severe in the last 20 years.

Question 20

Few algae are found growing on gravel and sand beaches.

Question 21

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

Question 22

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 23

An individual coral animal is known as a(n) ________.

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

Question 24

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 25

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

Question 26

Water must be warmer than ________ degrees Centigrade to support a reef of corals with zooxanthellae.

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

Question 27

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 28

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 is correct.

Question 29

Intertidal communities have low productivity because of high wave activity.

Question 30

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 31

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 as well as shells and worm tubes
E) coral polyps and calcareous algae, shells and worm tubes, and volcanic action and subsidence

Question 32

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 33

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

Question 34

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 is correct.

Question 35

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

Question 36

Blades are the photosynthetic organ of seaweed.

Question 37

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) organism's metabolism

Question 38

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 is correct.

Question 39

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 40

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

Question 41

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

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

Question 42

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 43

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

Question 44

Marine vascular flowering plants include all of the following except ________.

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

Question 45

The disruption of sediment by feeding and burrowing organisms is called ________.

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

Question 46

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 47

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 is correct.

Question 48

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 49

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 50

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

Question 51

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

Question 52

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

Question 53

Brown algae include ________.

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

Question 54

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 55

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

A) understory, canopy, algae turf
B) canopy, understory, algae turf
C) canopy, understory, intertidal
D) inshore, kelp canopy, offshore

Question 56

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

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

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 59

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

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

Question 60

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 61

In the Riftia-symbiont relationship, the benefit to the host during mutualism includes ________.

A) organic matter, that is, food
B) protection from predation
C) protection from competition for space
D) protection from parasites
E) a predation advantage

Question 62

The key special chemical used by chemosynthetic communities at hot vents is ________.

A) nitrate
B) phosphate
C) silicate
D) hydrogen sulfide
E) methane

Question 63

Dessication is the biggest issue for rocky shore benthos living in the ________.

A) pelagic zone
B) neritic zone
C) supralittoral
D) littoral
E) sublittoral

Question 64

A common mode of feeding for benthos is ________.

A) filter-feeding
B) predation
C) grazing
D) scavenging
E) All of these are common.

Question 65

In the Riftia-symbiont relationship, the benefit to the symbiont during mutualism includes ________.

A) chemicals for chemosynthesis
B) a habitat
C) protection from predators/consumers
D) All of these are correct.
E) None of these is correct.

Question 66

Which of the following is not true about deep-sea coral and tropical reef coral?

A) They are both animals.
B) They are both cnidarians.
C) They both have polyps.
D) They both have symbionts.
E) All of these are correct.

Question 67

Which of the following properties is likely to decrease in a small, shallow tide pool at low tide?

A) oxygen
B) carbon dioxide
C) temperature
D) acidity
E) salinity

Question 68

The predominant source of food in abyssal plains is ________.

A) photosynthetic biomass produced on the seafloor
B) photosynthetic biomass produced at the surface
C) chemosynthetic biomass produced at hot vents
D) chemosynthetic biomass produced at cold seeps
E) None of these is correct.

Question 69

Benthos can be all of the following except ________.

A) sessile
B) motile
C) autotrophic
D) heterotrophic
E) holoplanktonic

Question 70

The key special chemical used by chemosynthetic communities at salt seeps is ________.

A) nitrate
B) phosphate
C) silicate
D) hydrogen sulfide
E) methane