Coral NutritionCoral Nutrition

Coral polyp eating marine worm

Heterotrophy Heterotrophy Versus Versus

AutotrophyAutotrophy

Heterotrophic NutritionHeterotrophic Nutrition

General feeding modes:1. predaceous carnivores capturing live

prey2. detritus feeding3. absorption of dissolved organic

matter from surrounding water

Heterotrophic NutritionHeterotrophic Nutrition

Heterotrophic Feeding Methods:1. Tentacles capturing prey2. Suspension feeding and trap

particles with mucus3. Feed by mesentery filaments

The majority of hermatypic and ahermatypic corals feed on plankton or DOM

Heterotrophic NutritionHeterotrophic NutritionActive predation:• Tentacles capture prey• Found mostly on those that rely on

heterotrophic food sources• Hermatypic corals have smaller

tentacles and small polyps• Tentacles usually extend at night and

retract during the day

Polyp Anatomy RevisitedPolyp Anatomy Revisited

Coral Coral Polyp Polyp AnatomyAnatomy

NematocystNematocyst1. True nematocysts2. Spirocysts3. Ptychocytes

Nematocyst Nematocyst DischargeDischarge

http://www.youtube.com/watch?v=-Tp38DUjUnM

Stimulus for Nematocyst Stimulus for Nematocyst DischargeDischarge

• Mechanical stimulus.• Chemical stimulus (e.g., amino

acids) lowers the threshold for mechanical stimulus.

Feeding in Feeding in HydraHydra

Feeding in Feeding in HydraHydra

Feeding in Feeding in HydraHydra

Feeding in Feeding in HydraHydra

Feeding Response in Feeding Response in FungiaFungia

http://reefkeeping.com/issues/2007-05/atj/index.php

Mesenterial Mesenterial FilamentsFilaments

Fungia scutariaFungia scutariaCiliary Mucoid FeedingCiliary Mucoid Feeding

Ciliary Mucoid FeedingCiliary Mucoid Feeding

Coral Slime- Mucoid Feeding• zooxanthellae produce lots of

carbs• excess is trapped in mucus

produced by coral and expelled (DOM)

• DOM feed on by other orgs• May be a food source for

symbionts or to clean sediment off coral

Sediment ClearingSediment Clearing

Sediment ClearingSediment Clearing

Sediment ClearingSediment Clearing

http://www.youtube.com/watch?v=19ytYeqvTBc

Autotrophic NutritionAutotrophic Nutrition

PhotosynthesisPhotosynthesis

6H2O + 6CO2 + light C6H12O6 + 6O26H2O + 6CO2 + light C6H12O6 + 6O2

Aerobic RespirationAerobic Respiration

C6H12O6 + 6O2 6H2O + 6CO2 + energyC6H12O6 + 6O2 6H2O + 6CO2 + energy

Zooxanthellae in Gastrodermal Cells of Corals

Zooxanthellae:Zooxanthellae:Symbiodinium microadriacticumSymbiodinium microadriacticum

Zooxanthellae in Zooxanthellae in PlanulaPlanula

Transmission of Transmission of Zooxanthellae into Host Zooxanthellae into Host

TissuesTissues

• Maternal (direct) transmission.

• Environmental (indirect) transmission.

Maternal TransmissionMaternal Transmission

Environmental Environmental TransmissionTransmission

Hermatypic Versus Hermatypic Versus Ahermatypic CoralsAhermatypic Corals

Hermatypic Hermatypic CoralCoral

J. P. Hoover, 1998J. P. Hoover, 1998

Ahermatypic Ahermatypic CoralCoral

Benefits to the Coral HostBenefits to the Coral Host

• Higher rates of calcification (skeleton deposition).

• Energy and materials for growth, repair, and reproduction.

• Removal of chemical wastes from animal metabolism (nutrient recycling).

• Receive chemicals that absorb damaging ultraviolet light.

Benefits to the Algal SymbiontBenefits to the Algal Symbiont

• Chemical wastes from animal metabolism are important inorganic nutrients for plants (nutrient recycling).

• Surrounding animal tissues can concentration substantial amounts of ultraviolet light absorbing compounds.

• Zooxanthellae, nonmotile single cells, get a place to live in the crowded reef environment.

Chemical Chemical Recycling Recycling Between Between

Zooxanthellae Zooxanthellae and Their and Their

Coral HostsCoral Hosts

Heterotrophy Heterotrophy Versus Versus

AutotrophyAutotrophy

Polyps Adapted for Capturing FoodPolyps Adapted for Capturing Food

Fungia scutariaFungia scutariaAn Exception?An Exception?