Marine biology

Question 1

What are the 3 modes of life in the sea?

Answer 1

1. Pelagic
2. Shifting & Ephermal
   - Plankton - drift
   - Nekton - swim
3. Benthic/demersal (bottom)

Question 2

How do pleagia maintain buoyancy?

Answer 2

Through spines/hairs, trailing threads, flattened body, inclusion of oils/fats and gas chambers

Question 3

Give 4 examples of plankton

Answer 3

• larvae
• cnidarians such as jellyfish
• zooplankton
• phytoplankton

Question 4

Give 4 examples of nekton

Answer 4

• bony fish
• elasmobranchs (sharks and rays)
• marine mammals
• cephalopods (octopi and squid)

Question 5

What is a characteristic of benthic dwellers?

Answer 5

Often have attachments to the surface

Question 6

What are interface animals?

Answer 6

Animals that exploit the interface between the sea and the air, often have sail appendages for dispersal

Question 7

What are porifera?

Answer 7

Parazoa (sponges) refers to ostia (pores)

Circulate water via special cells, and are the most primitive of marine multi-cellular organisms

Question 8

Describe the anatomy of the eumatazoa/cnidarians

Answer 8

• Radially symmetrical
• Diploblastic (2 types of tissue)
• Mesoglea is invaginated between endoderm (making the enteron/gut) and ectoderm
• Has an incomplete digestive tract
• stinging cells (nematocysts) on marginal tentacles

Question 9

What are the 3 main body parts of molluscs?

Answer 9

1. Muscular foot
2. Visceral mass
3. Mantle

Question 10

What are the 4 types of molluscs (with examples)?

Answer 10

1. Bivalves (2 shells) - clams, oysters
2. Gastropods (single shell) - sea snail
3. Polyplacophoran - chitons
4. Cephalopods - octopus, squid, cuttlefish

Question 11

What are 3 features of anthropods?

Answer 11

• segmented bodies
• jointed appendages
• exoskeleton

Question 12

Name 6 features of echinoderms

Answer 12

1. Spiny skin
2. Radial anatomy
3. Pentamorous (5 parts)
4. Water vascular system
5. Endoskeleton
6. Tube feet

Question 13

What are the features that must be present in chordates?

Answer 13

NOT NECESSARILY A SPINE

• Dorsal, hollow nerve chord
• Notochord
• Pharygeal slits
• Post anal tail

Question 14

What are the 2 types of cnidarians?

Answer 14

Polyps - sat on the ground with mouth up

Medusa - swimming with mouth down

Question 15

What are the 2 types of polyps?

Answer 15

Hard case - calcified skeleton provide protection and support, live individually
Soft case - proteinaceous case and live colonially

Question 16

How do adaptations for swimming differ with body size?

Answer 16

smaller - need to maintain buoyancy therefore high surface area
larger - inertia, torpedo shapes

Question 17

What are the advantages of burrowing?

Answer 17

Good for responding t osmotic/thermal/respiratory stress

Question 18

Describe the mechanism echinoderms use to move

Answer 18

• Central ring canal extends out into radial canal
• Water flows through radial canal, into lateral canal and ampullae which then contracts
• Causes extension in tube feet

Question 19

What are passive suspension feeders?

Answer 19

animals that expose a large surface area to currents to feed on suspended particles using cilia/filtration/sticky mucus

Question 20

How are sponges active suspension feeders?

Answer 20

• Actively generate currents using flagella to force water out of the osculum and in through the ostia
• Food trapped by the flagella flows down the collar into the cell body

Question 21

What are deposit feeders?

Answer 21

• Feed on sediment of microalgae and particulate organic matter
• Either at surface or under sediment

Question 22

What are the advantages and disadvantages of internal fertilisation?

Answer 22

• Higher chance of fertilisation

- Lower chance of finding a mate

Question 23

What are the advantages and disadvantages of external fertilisation?

Answer 23

• Do not have to find a mate

- Gametes at risk of predation and dilutiojn

Question 24

Which 5 ways can improve the odds of external fertilisation?

Answer 24

1. Ensuring sperm transfer
2. Volume of gametes
3. Reduce distance between sexes
4. Minimal water turbulance
5. Gamete behaviour (active swimming)
6. Timing

Question 25

Describe gonochoristic fertilisation

Answer 25

- Form aggreagations and take up spawning posture | - One individual releases spawning hormone triggering spawn of all other individuals

Question 26

Give an example of a simultaneous hermaphrodite

Answer 26

Aplysia (sea hare) forms mating chains either laying eggs or depositing sperm alternatively

Question 27

What are protandrous hermaphrodites?

Answer 27

Male first

Question 28

Explain the mating systems of a) Crepidula fornicata b) Amphiprion ocellaris

Answer 28

a) form a stack where bottom most male becomes female | b) oldest and largest male becomes the female

Question 29

What are the 3 different reproductive systems of crustanceans?

Answer 29

1. Simultaneous hemaphrodites 2. Androdioecy - hemaphrodites and dwarf males 3. Dioecy - females and dwarf males

Question 30

How do barnacles reproduce?

Answer 30

Female barnacle broods eggs which released as cyprid larvae which metamorphose head down on a suitable surface

Question 31

What are the 3 methods of asexual reproduction?

Answer 31

1. Fission - one idividual separates into 2 individuals 2. Budding - new organism growing off the original organism 3. Fragmentation (pedal laceration) - New organism forms off fragment of parent