Module 12

Question 1

Benthos

Answer 1

Marine organisms that live on the sea bottom

Question 2

Nekton

Answer 2

Marine organisms that swim strongly enough to move against the ocean current

Question 3

Plankton

Answer 3

Marine organisms that cannot swim strongly enough to move against the ocean current

Question 4

Meiofauna

Answer 4

Microscopic invertebrates living within the interstitial

Question 5

Identify the following organisms as benthos, nekton, or plankton. a. sand dollar, b. larval fish, c. shark, d. jellyfish, and e. crab.

Answer 5

a. benthos
b. plankton
c. nekton
d.plankton
e. crab

Question 6

Why is the continental shelf also called “subtidal”?

Answer 6

It stays underwater regardless of the tides.

Question 7

How does wave action determine the types of substrate particles present in a shelf enviroment?

Answer 7

Heavy wave action washes away fine particles and leaves mainly sand. Areas without much wave action, or those protected from it, have fine sediments

Question 8

What are the three types of organisms that make up the benthos?

Answer 8

Infaunal organisms, epifaunal organisms, and meiofaunal organisms.

Question 9

Which type of soft substrate contains little oxygen and lots of organic matter?

Answer 9

A muddy bottom substrate.

Question 10

Which type of community has a large number of species living in it: a soft-bottom estuary or a soft-bottom shelf community?

Answer 10

Soft-bottom shelf community.

The physical conditions in estuaries are too unstable for most organisms

Question 10

Are the infauna evenly distributed throughout the substrate in a soft-bottom subtidal community?

Answer 10

The infauna are not evenly spaced in the substrate of soft-bottom shelf communities.

Question 11

What is the major food source of the unvegetated soft-bottom shelf communities?

Answer 11

Deitrus

Question 12

What does scuba stand for

Answer 12

self-contained underwater breathing apparatus

Question 13

You are studying a shelf community with a sandy-bottom substrate. What type of feeding mechanism would you expect most of the organisms living there to use?

Answer 13

Most of the organisms in a sandy-bottom shelf community will use suspension feeding.

Question 14

What makes meiofauna different from the infauna in a substrate?

Answer 14

Meiofauna are small enough to fit in between the individual particles of the substrate.

Question 15

A student tells you he observed a soft-bottom community in which suspension feeders and deposit feeders were roughly equal in number and lived in close proximity to one another. Why should you be skeptical of this student’s report?

Answer 15

Suspension feeders do not like living near deposit feeders because deposit feeders churn through sediments looking for food.(Which would clog their food-gathering systems) It is also rare to find them in equal numbers because they generally live in areas with different substrates.

Question 16

What kind of seagrass do you typically find in the tropics? what kind do you typically find in temperate regions?

Answer 16

In the tropics, turtle class is most commonly found, while in temperate areas eelgrass is more common.

Question 17

Seagrasses do not provide much live plant food to organisms living in the community. How does their tremendous primary productivity get into the food chain, and what other benefits do they provide for their community?

Answer 17

Many organisms feed on the decaying seagrass. Seagrass roots aid in keeping the soft substrate more stable, seagrass blades provide shelter for many creatures, and the blades are locations on which both algae and organisms directly dwell.

Question 18

Name at least two organisms that feed directly on live seagrasses.

Answer 18

Manatees and sea turtles

Question 19

What types of organisms dominate the hard-bottom shelf communities: infauna or epifauna? Why?

Answer 19

Epifauna, because there is little soft substrate into which infauna can bury.

Question 20

Why are seaweeds so common in hard-bottom shelf communities and not in soft-bottom shelf communities?

Answer 20

Seaweeds need a hard surface onto which they can hold because they do not have roots that can anchor them to a soft substrate.

Question 21

What factors keep most animals from grazing on seaweeds?

Answer 21

Some seaweeds have special chemicals that give them a bad flavor, some are leather-like, and others incorporate calcium carbonate into their tissues to give them a hard-shelled outer surface

Question 22

What are some of the environmental requirements necessary for kelp growth?

Answer 22

Sunlight, a hard substrate, and cold nutrient rich water

Question 23

What is the difference between a kelp bed and a kelp forest?

Answer 23

A kelp bed has kelp that are not tall enough to reach the surface of the water, while a kelp forest is composed of kelp that grow all the way up to the surface, forming a canopy.

Question 24

Which has more chromosomes, the cells of the gametophyte generation of kelp of the cells of the sporophyte generation of kelp?

Answer 24

The sporophyte generation of kelp.

Question 25

A professor tells you that you are looking at a full-grown giant kelp. However you are looking at it with a microscope, and you can see the entire organism. How can the professor be correct?

Answer 25

You are looking at an individual from the gametophyte generation of giant kelp.

Question 26

Where among the layers of kelp understory might the following inhabitants live: brittle starfish, octopuses, fishes, small sessile suspension feeders?

Answer 26

Brittle starfish: among the holdfasts of kelp Octopuses: substrate between kelps Fishes: in the water column among the blades of kelp small sessile suspension feeders: either directly on the stipes and blades of kelps or on the substrate between kelps

Question 27

Explain why, during a sea urchin population explosion, kelp plants are so easily killed off yet are rarely completely eaten.

Answer 27

During a sea urchin population explosion, there is not enough drift kelp on which to feed. So sea urchins crawl along the bottom and eat the holdfasts of the kelps.