Ms. Springstroh Source of information:

 Almost all corals are colonial organisms ◦ Composed of hundreds of thousands of individual polyps  Polyps are animals  Polyps in a colony are connected by a thin sheet of tissue (cells aggregated together) ◦ Polyps are sessile

 Reefs form when polyps secrete calcium carbonate skeletons ◦ Limestone ◦ CaCO 3

 Calcium carbonate skeleton secreted by the lower portion of the polyp ◦ Produces a cup-like structure called a calyx, which the polyp sits in ◦ Bottom of cup is called a basal plate  Every so often, a coral polyp will lift itself up off its basal plate and secrete a new calyx ◦ More CaCO 3 ◦ This is how a coral reef grows

 When corals are stressed, they retract into their calyx so that no part of the polyp is exposed above its skeleton  Polyps also may extend out of their calyx, especially when they feed

 Free-swimming coral larva, called a planula, attaches to rocks or other substrates near shallow areas, such as by islands or the edges of continents  Planula metamorphoses (transforms) into a polyp  Polyps divided over and over to form reefs

 Corals may utilize asexual or sexual reproduction ◦ Asexual reproduction: reproduction that does not require gametes (sex cells)  A new polyp– a clone of its parent– “buds” off from the parent and begins a new colony itself ◦ Sexual reproduction: some corals release gametes (sperm and egg cells) into the water  Egg and sperm combine to form planulae

 In some reefs, the all the coral species release their sperm and egg at the same time ◦ Called broadcast spawning  Influenced by temperature, length of day, lunar cues, time of sunset  Planulae swim toward the light ◦ Become part of the waters at the surface of the ocean  Current transports planulae  Planulae eventually swim back toward bottom of ocean ◦ Will settle there if conditions are favorable  metamorphose  build a colony

 Zooxanthellae are photosynthetic algae which live in corals’ tissues  Have a mutualistic symbiotic relationship with corals ◦ Symbiosis: close relationship between two organisms of different species ◦ Mutualism: a symbiotic relationship in which both species benefit (symbolized by + / + )

 Corals provide zooxanthellae with a protected environment in which to live, and with the materials needed for photosynthesis  Zooxanthellae help the coral eliminate waste, provide the coral with oxygen and glucose, & help the coral secrete its skeleton ◦ If the coral has enough glucose/ “energy”, it can secrete a calcium carbonate skeleton and grow! ◦ This energy comes from the ‘waste’ molecules produced by the zooxanthellae during photosynthesis.  Both of these contribute to the “recycling of nutrients”  This mutualistic symbiotic relationship is VERY VALUABLE because tropical waters are nutrient-poor!

 Lime (calcium and oxygen) is dissolved in sea water  Corals have carbon and oxygen in their cells ◦ Combines with calcium and oxygen from the water ◦ Produces CaCO 3

 Chalk = contains calcium  Clear liquid from chalk + vinegar (C 2 H 4 O 2 ) mixture = dissolved lime = “sea water”  Baking soda = sodium bicarbonate, NaHCO 3 = coral’s cells ◦ Adding baking soda + water to dissolved calcium (chalk + vinegar mixture)  CaCO 3

 Pour 250mL of vinegar into a beaker.  Break chalk into small pieces. Put into beaker.  Label beaker.  Let stand overnight.

 Pour off some clear liquid from chalk mixture into cup labeled “dissolved limestone”. Rinse your beaker.  Obtain 240mL of tap water in beaker. Add 3-4 tablespoons baking soda; stir, then let stand for 15 minutes.  Pour off some clear liquid from baking soda beaker into another cup labeled “dissolved baking soda”. Rinse your beaker.  Pour “dissolved baking soda” into “dissolved limestone” beaker. Observe what happens.

 Mixing of the “dissolved limestone” and the “dissolved baking soda” represents a coral polyp extracting calcium from sea water, combining it with carbon dioxide, and producing CaCO 3.  Chalk = contains calcium  Clear liquid from chalk + vinegar (C 2 H 4 O 2 ) mixture = dissolved lime = “sea water”  Baking soda = sodium bicarbonate, NaHCO 3 = coral’s cells ◦ Adding baking soda + water to dissolved calcium (chalk + vinegar mixture)  CaCO 3  Source:

 Write a paragraph (using at least four complete sentences) about how a coral builds its skeleton. Try to use as many examples from this lab as possible. ◦ Things to think about and include: ◦ What does the white precipitate represent? ◦ What does the “dissolved limestone” represent? ◦ What does the “dissolved baking soda” represent? ◦ What does mixing the “dissolved limestone” and “dissolved baking soda” represent?

 White precipitate= calcium carbonate ◦ How does it form?  Coral polyp extracts calcium from sea water (vinegar + chalk mixture, aka dissolved limestone) & combines it with carbon dioxide

 Corals can build 3 types of reefs: ◦ Fringing: grows very close to or on shore ◦ Barrier: also grows close to shore but has a lagoon separating it from the shore ◦ Atoll: a ring of coral that surrounds a lagoon, often grows on a submerged mountain or volcano

FRINGING BARRIER ATOLL

Midway Atoll

Coral Bleaching  Zooxanthellae provide coral with greenish-brown color  When under stress, corals expel their zooxanthellae ◦ Coral therefore loses its color and one of its foods sources  Result: coral polyps will die ◦ Leave behind white calcium carbonate skeleton

ELKHORN CORAL BRAIN CORAL TABLE CORAL

PILLAR CORAL STAGHORN CORAL

 Food chains show how living things get their nutrients, and how these nutrients are passed from one organism to another  Producers produce their own nutrients, via photosynthesis  Consumers eat other organisms to obtain nutrients ◦ 3 kinds of consumers:  Herbivores: eat only plants  Carnivores: eat only animals  Omnivores: eat both plants and animals

 A trophic level is the position in a food chain an organism occupies  The first trophic level is made up of producers. These producers are called primary producers. ◦ Use photosynthesis to create nutrients such as sugars ◦ Examples within a coral reef: seaweed, zooxanthellae

 The next trophic level is made of primary consumers– organisms which consume the primary producers, OR the ‘waste’ products given off by the primary consumers ◦ Examples within a coral reef: corals, sponges  Secondary consumers prey on primary consumers ◦ Examples within a coral reef: grouper, turtles, crown-of-thorns sea star

 Feeds on corals by pushing its stomach out through its mouth ◦ Covers coral colony with its stomach ◦ Digests coral tissue

 Tertiary consumers prey on secondary consumers ◦ Examples within a coral reef: gray reef shark (also considered a top predator: has no natural enemies)

 Only about 10% of the energy at one trophic level on a food chain is passed onto the next level. ◦ The remaining 90% of energy will be used by the organism at the lower trophic level to do its normal activities, such as movement & respiration, OR will be lost during the energy transfer.