Locomotion and Feeding on the Seabed

Question 1

a) Intertidal (littoral) zone

b) sublittoral zone
- Kelp forests hold on to rocks via (c)

Answer 1

a) 0-200m, transition between marine and terrestrial environments or ecotone
b) receive enough light for photosynthesis, see thriving kelp forests etc
c) holdfasts

Question 2

Ecotone

Answer 2

Transitional environment

Question 3

Benthic

Answer 3

ecological region at the very bottom of the sea

Question 4

Dysphotic zone is located on the ____ slope

Answer 4

Continental

Question 5

Where is benthic productivity at its highest?

Answer 5

underneath areas of high surface productivity

• Mainly on continental shelves
• Affected by surface ocean currents

Question 6

What is the abyssal plain like? (4000m and deeper)

Answer 6

• Little known habitat – only accessible via dredge and some submersibles and ROVs
  • Little to no sunlight
  • Stable abiotic conditions (temperature, salinity, Oxygen
  relatively high, very high pressure
  • Bottom currents usually slow
  • Suit low energy lifestyles (think
  echinoderms!)

Question 7

How do abyssal zones receive nutrients?

Answer 7

• Marine snow
• bonanzas (whale death and sinking)
• dead nekton sinking to the bottom
• vertical migrations

Question 8

Form of energy production dominates in deep sea hydrothermal vents

Answer 8

Chemosynthesis

Question 9

How are species distribution influenced by substrate choice?

Answer 9

• burrowing lifestyle can only exist in soft substrates
• oxygen availability reduced in tightly packed substrates
• particle size increases with increasing current size
• living in substrates limited to soft substrates

Question 10

Describe the lifestyle of a sessile benthic animal? Given an example?

Answer 10

• Don’t move as adults, disperse as larvae

eg. acorn barnacles (semibalamus with naupilus larvae)

Question 11

Describe the lifestyle of a slow moving species

Answer 11

• Ciliary gliding flatworms

- Echinoderms, in Echinodomea

Question 12

Describe locomotion of Nereis, the errant Ragworm

What about when just walking?

Answer 12

Preparatory stroke:
• Anterior parapodial muscle contracts
• Longitudinal muscles on opposite side contract
• Chaetae retracted

Power stroke:
• Posterior parapodial muscle contracts
• Longitudinal muscles on same side contract
• Chaetae protracted

WALKING

• body straight, only uses parapodial muscles

Question 13

Which species burrow ?

Answer 13

Bivalves
Polychaete lugworm
Crustaceans

Question 14

Describe how a mollusc burrows

a) function of abductor muscles
b) function of protractor muscles
c) function of retractor muscles

Answer 14

1) EXCAVATION (shell gapes and foot pushed down)
2) MOVEMENT IN (tip of foot swells by blood inflow)
3) BODY DRAWN DOWN

a) contract to free the shell
b) contract to trap blood in tip of foot like an anchor
c) contract to shorten foot to draw body down

Question 15

How do hard substrate browsers feed?

Answer 15

by grazing using radula eg. limpets

Question 16

Give an example of a direct filter feeder

Answer 16

Arenicola (Polychaete worm)

Question 17

Give an example of an indirect filter feeder

Answer 17

Terebella (Polychaete worm) using ciliated tentacle palps

Question 18

Describe the 5 different methods of suspension feeding

Answer 18

1) true sieving (RARE)
2) SPONGE flagella suspension
3) mucus sheet feeding eg. sea squirt
4) ciliary mucous feeding, eg. peacock worm
5) non-ciliary suspension feeding
6) sit and wait predators eg. bobbit worm

Question 19

give an example of a species that lives on a living substrate

Answer 19

ghost shrimp on a hydroid

Question 20

Give an example of an active forager

Answer 20

Ragworm, Nereis