Types of CoralsTypes of Reefs

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Pillar (Digitate) Coral

• Upward cylinders

• Look like fingers or

cigars

• No secondary branching

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Table Corals

• Plate like with polyps extending upward

• Increased surface area for photosynthesis

• Easier for tentacles to capture zooplankton

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Branching Coral

• Primary and secondary branches

• Resemble bushes

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Elkhorn Coral

• Thick, sturdy, flat, antler-like branches

• Fast growing

• Survive in heavy

wave action

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Foliase Coral

• Whorl-like pattern

• Look like flower petals

• Increased surface area

• Provide shelter for animals between “petals”

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Massive Corals

• Ball/boulder shape

• Very sturdy

• Very slow growing

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Encrusting Coral

• Grow flat instead of up

• Adhere to rock

• Protected from wave action

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Mushroom Coral

• Mushroom shape

• Flat or dome oval

• Solitary

• Unattached

• Indo-Pacific waters

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Types of Reefs10/18

Fringing Reefs

• Most common

• Project seaward from the shore

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Barrier Reefs

• Border shorelines

• Separated from land by lagoon of open, often deep water

fringeland

barrier

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Atoll

• Fringe reef forms

• Volcanic island subsides

• Usually circular with central lagoon

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Parts of the ReefDetermining Factors

• Bottom topography

• Depth

• Wave action

• Current

• Temperature

• LightLight

• Sediment

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Reef Flat Zone

Sheltered side of reefVariable depth: exposed at low tide

Seagrass bedsSubstrate: loose sand and coral

Encrusting and filament algae common

Variable temp and salinity

Protected from waves

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Reef Crest

Highest point on reef Exposed at low tide

Severe wave action: little live coral Stout branching coral

Small animals live protected among nooks and crannies

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Fore Reef

Low tide mark to deep water

Deep channels between buttresses

Butresses: stabilize reef and dissipate wave action

Channels: drain reef debris & sediment to deeper water

Abundant O2 + hiding spaces = small fish

Small fish bring big fish! Yummy!Deep dark water = sponges, & non-reef building coral

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