Deck 15: Benthic Life Habits

Question 1

Meiobenthos

A) Are greater than 1 mm in size
B) Are always epifaunal
C) Are smaller than 0.5 mm
D) Are smaller than microbenthos

Answer 1

C

Question 2

As the silt-clay content of sediment increases

A) We can tell that the variability of current strength increases
B) The current strength decreases
C) The current strength increases
D) The water depth must increase

Answer 2

B

Question 3

Demersal species

A) Spend most of their time in the water column
B) Are mobile but associated with the seabed
C) Move along the bottom with muscular tube feet
D) Burrow into soft sediments

Answer 3

B

Question 4

An example of a hydrostatic skeleton would be

A) The chitin of an arthropod
B) Bones in a fish
C) Axial skeleton of a whale
D) A bivalve foot

Question 5

Interstitial animals all

A) Are usually worm-like in shape
B) Can swim away from the sediment
C) Have high fecundity
D) All of the above

Question 6

The RPD

A) Is a border between the presence and absence of bacteria
B) Is only found in estuarine sediments
C) May only be a horizontal surface
D) Is a border between oxidative and reducing processes in sediments

Question 7

The most energetically profitable means of breaking down organic matter is obtained by

A) Sulfide-oxidizing bacteria
B) Aerobic bacteria
C) Fermenting bacteria
D) Sulfate-reducing bacteria

Question 8

Hydrogen sulfide is associated with

A) The absence of oxygen in sediment pore waters
B) The presence of strongly burrowing animals in sediments
C) The presence of oxygen in sediment pore waters
D) Strong bottom currents

Question 9

Deposit feeders

A) Routinely digest cellulose and other refractory compounds in sediments
B) Can digest diatoms but poorly digest bacteria
C) Can usually digest diatoms and many bacteria
D) Digest bacteria only

Question 10

Some large benthic invertebrates lack a gut because

A) They feed on dissolved organic matter
B) No large benthic invertebrates lack a gut
C) They have very low metabolic needs
D) They have symbiotic bacteria, which provide nutrients

Question 11

If you are a deposit feeder, it may be bad to process sediment through your gut too quickly because

A) You may suffer osmotic problems
B) You will not have an opportunity to expose the food to digestive enzymes
C) The sediment will become too watery
D) You will be exposed inevitably to sulfide

Question 12

Passive suspension feeders may change their overall body form as they grow larger because

A) They develop reproductive structures
B) They always grow into turbulent flow
C) They may grow in complex flow near the bottom, but unidirectional flow off of the bottom
D) They must be able to bend over in flow off of the bottom in all cases

Question 13

Growing erect into the current may be a problem owing to

A) A low Reynolds number
B) Oxygen overload
C) Oversupply of particles
D) Drag

Question 14

In most cases, suspension feeders capture particles by means of

A) Direct interception
B) Sieving
C) Gravitational impaction
D) Inertial impaction

Question 15

A means of treating food unique to deposit feeders is

A) The lack of digestive enzymes in the midgut
B) The use of surfactants in the gut
C) Precipitation of soluble amino acids in the gut
D) Swimming from the bottom into the water to get food particles

Question 16

Wood boring

A) Is found only in the bivalves
B) Involves chemical action only in bivalves
C) Is found only in isopods
D) Is found in bivalves and isopods

Question 17

Biogenic graded bedding

A) Usually involves transport of coarse particles to the surface
B) Is generated by strong wave action in the intertidal zone
C) Is commonly caused by head-down deposit feeders
D) None of the above

Question 18

Deposit feeders affect sediments by

A) Altering grain size
B) Increasing the sediment water content
C) Accelerating decomposition of organic matter
D) All of the above

Question 19

Most suspension feeders capture particles by

A) A sieving process
B) Direct inertial impact on feeding structures
C) Using cilia to stop current flow
D) Gravitational deposition of particles

Question 20

Suspension feeders

A) May actively sort and retain higher food quality particles
B) Collect particles only by passively inserting a feeding structure into a current
C) Cannot sort among particle types, once they impact a feeding structure
D) Do much better when particle density is extremely high

Question 21

Marine herbivores

A) Are quite variable in the ability to feed on sea grasses
B) Cannot feed on macroalgae with secondary compounds
C) Can digest and assimilate all marine photosynthesizers
D) Can never feed on wood

Question 22

Many crabs and lobsters have cutter and crusher claws

A) To use crusher claws for feeding and the cutter claws for combat with other males
B) With the cutter claws in the juvenile stage and the crusher stage in mature adults
C) To manipulate prey with the cutter claws and break open prey with the crusher claws
D) All of the above