Lecture 7

Question 1

Coral reefs (support)

Answer 1

Support 1/3 of all marine species, diversity and more than 500 million people’s livelihood

Question 2

Calcifying cnidaria - anthozoans and some hydrozoans (general anatomy)

Answer 2

• Coral polyps are often colonial
  
  • Coenosarc joins the polyps laterally
• The polyps produce and rest within their calyx
• The basal plate rests on the calyx

Question 3

Coenosarc

Answer 3

The living tissue overlying the stony skeletal material of the coral

Question 4

Calyx

Answer 4

Collective name for several cup-like structures in animal anatomy (CaCO3)

Question 5

Theca

Answer 5

Polyp walls surrounding the calyx

Question 6

Symbiotic relationships (zooxanthellae)

Answer 6

• Zooxanthellae (dinoflagellates)
• Nutrients, O2, acid-based balance, colours
• Loss of symbionts = loss of energy (about 60%)
• Loss of energy = loss of productivity
  
  • Productivity includes growth and reproduction

Question 7

Symbiote localization and functionality

Answer 7

• Zooxanthellae algae enter the GVC (also called coelenteron)
• Embedded in gastroderm (endoderm)
• Trapped in symbiosome space

Question 8

Symbiosome space

Answer 8

Intervening space between the symbiosome membrane and the bacteroid. All nutrients and signals must transverse the symbiosome space

Question 9

Breakdown of the coral-algae symbiotic relationship

Answer 9

1.) Coral’s metabolism produces CO2 and NH3 within the host cell
2.) Carbonic anhydrase (CA) converts CO2 into H+ and HCO3-
3.) H+ is actively pumped by the host into the symbiosome space
4.) HCO3- is transported from the host cell into the symbiosome space, reacts with H+ to form CO2 and H2O
5.) NH3 enters the symbiosome space, reacts with H+ to form NH4+
6.) Algae collect and metabolize CO2 and NH4+ to produce sugars and O2

Question 10

Warm water

Answer 10

= More algae activity

Question 11

High CO2 water

Answer 11

= More algae activity

Question 12

Loss of algae

Answer 12

= Starving corals

Question 13

Starving corals

Answer 13

= More sensitive to stress

Question 14

Calicoblasts

Answer 14

Calcifying cells

Question 15

Desmocytes

Answer 15

Anchoring cells

Question 16

Exocytosis

Answer 16

The fusion of secretory vesicles with the plasma membrane; results in the discharge of vesicles content into the extracellular space and the incorporation of new proteins and lipids into the plasma membrane

Question 17

Synchronized broadcast spawning

Answer 17

• Broadcast occurs once/year at specific months (temperature), days (lunar effect) and hour (sunset time)

Question 18

Reproductive cycle (corals)

Answer 18

1.) Gametes synchronously ‘broadcast’ into sea water
2.) Fertilisation occurs externally
3.) Planula larvae form (free-swimming; days-weeks)
4.) Settlement and formation of skeletal base on substrate
5.) Polyp forms and gains zooxanthellae
6.) Asexual fragmentation/budding

Question 19

Colonial cnidaria (hydrozoans)

Answer 19

• Often colonial
  
  • Monopodial: oldest at the top
  • Sympodial: oldest at the base

Question 20

Gastrozooids

Answer 20

• Specialized colony (zooid, kind of like an organ)
• Feeding/digestion

Question 21

Dactylozooids

Answer 21

• Specialized colony (zooid, kind of like an organ)
• Defensive

Question 22

Gonozooids

Answer 22

• Specialized colony (zooid, kind of like an organ)
• Reproduction

Question 23

Nectophores

Answer 23

• Specialized colony (zooid, kind of like an organ)
• Swimming bells

Question 24

Pneumatophore

Answer 24

• Specialized colony (zooid, kind of like an organ)
• Floatation