LEC 18 - CORAL REEFS I

Question 1

what is the difference between a bioherm and a biostrome?

Answer 1

a bioherm is lens shaped while a biostrome is flat. both give accounts of the geological record

Question 2

how do past corals compare to our present day corals?

Answer 2

past corals were the rugose corals (they’re dead); our present corals come from the tethys sea

Question 3

where do corals like to form? what conditions encourages this growth?

Answer 3

corals like to grow in shallow, tropical waters

remember, corals are allies to lesbians (like WLWS)
- warm: good
- low turbidity: good access to sunlight
- wind + currents: for mixing water to get max nutrient upwelling
- substrate to attach to

Question 4

how do scleractinian corals differ from soft corals?

Answer 4

scleractinian corals build calcified skeletons, while soft corals have an incompletely calcified skeleton (either some parts or not at all)

also scleractinan corals are hexacorals while soft corals are octacorals

Question 5

what are coral “builders” called?

Answer 5

scleractinian

Question 6

recall what phylum corals fall under. what implications does this have for their biology?

Answer 6

corals are cnidarians, so they have cnidocytes

Question 7

what are zooxanthellae? where do they chill?

Answer 7

zoox are photosynth algal symbionts that live in the coral endodermis

Question 8

aside from the typical plant/animal relationship, what else does zoox provide?

Answer 8

zoox gives the coral carbonate ions (CO3 2-) which it combines w calcium ions to form the calcium carbonate skeleton

Question 9

what is the relationship bw calcification and photosynthesis?

Answer 9

they augment one another, since they beget products the other needs

we observe this in corals growing significantly faster during clear days vs cloudy days and at night

Question 10

recall darwin’s atoll theory

Answer 10

1. corals grow around land - fringing reef
2. land begins to recede, leaving coral behind - barrier reef
3. land completely recedes, leaving coral behind - atoll

Question 11

what is a:
1. fringing reef
2. barrier reef
3. platform reef
4. atoll reef

Answer 11

1. corals that grow around land masses
2. coral separated from land by a lagoon
3. flat coral
4. reef encircling a lagoon

Question 12

how do corals grow? in what direction? what is the reef crest, flat, and front?

Answer 12

corals first found themselves on a substrate, and grow from windward (thats the way the nutrients come)

the reef crest is the advancing edge of the reef; the reef front (aka slope) is the part of the coral that takes the wave energy, and also some nutrient; the reef flat is the top of the reef that receives most of the sunlight

Question 13

how do corals adapt to wave energy?

Answer 13

• some just build dense to withstand the energy
• some adapt to disperse the energy (grooves)
• some just straight break for asex reprod