Corals and Coral Reefs

what are coral reefs often called

forests of the sea

Corals Phylum

Cnidaria

what are hard coral polyps external skeletons made of

calcium carbonate

what is the key to survival for coral growth

warm shallow spot

calyx

(calix: cup) part of skeleton directly under polyp, cup-shaped depression

what can a polyp do for protection

retract to hide

what colors

yellow, green, orange, purple

How coral grows

New coral begins as tiny planktonic (drifting) larva that settles on hard object in a warm, shallow spot and grows into a coral polyp. Then, a layer of polyp's cells touching surface secretes an exoskeleton that grows outward at the base. A few species can spend their lives as a single polyp (solitary corals) while most are colonial corals or "coral heads"

how do colonial corals grow

by budding, would become branching or encrusting corals

what is the meaning of the word zooxanthellae

zoo=animal, Xanth=yellow, Ella=small

what are zooxanthellae

single celled algae living in cells in their tissues

mutualism

both species benefit: zooxanthella (algal) and coral (animal)

how does mutualism happen among corals

zooxanthella (plant) cell exposed to sunlight begins photosynthesis (process of taking in co2 to produce o2). Then, coral (animal) cell uses oxygen for respiration and produces co2 and other waste (ammonia). zooxanthella uses co2 from coral cell for photosynthesis and other waste for nutrients. They also stimulate skeletal secretion.

types of calyx (calces)

separated, unseparated, missing side walls

septa (septum=fence)

partitions radiating inward (septae)

coral reef

a massive deposit of coral skeletons, hundreds, thousands, or millions of years of coral colonies growing together on a rocky bottom

coral reef evolution

subsidence: gradual sinking of the island, fringing reef: early stages when reef is small/close to shore, barrier reef: GU, two lovers point; the reef grows in extent, lagoon: region of shallow sea water, coral atoll: circle of coral islands, motus: small islets formed by mounds of coral piled up, guyot: submerged atoll

2 parts of a reef

(dead) reef flat: upper surface of reef, (alive) reef face: outer seaward surface

why is Guam unaffected by tsunamis

coral reef