What is coral?

It’s a living organism! It is an invertebrate 2 different types:

Reef Building: Hermatypic Solitary: Ahermatypic

Coral is cousins to jellyfish and anemones (Cnidarians)

Today we will talk mainly about reef building coral

Sun Coral Polyps

Where Can You Find Coral Reefs?

Coral is found all over the world: Tropical Temperate Polar

Only tropical corals build reefs

Coral reefs around the world

Coral Builds Reefs?

The animal portion of the reef is called a polyp

The polyp absorbs calcium carbonate out of the water

The calcium carbonate is used to build the reef

Reefs Corals Build

Corals can build three types of reefs: Fringing: grows close to 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

http://www.nos.noaa.gov/education/kits/

corals/media/coral04a_240.jpg

Coral are Cnidarians

Soft bodied Carnivorous Stinging tentacles

arranged in a circle around their mouth

Body symmetry Specialized tissues

Cnidarians

Usually two life stages: Polyp Medusa

Gastrovascular cavity Food is broken down

here but digested intracellularly

Cnidarians

Respiration and waste removal takes place through body walls

Nerve net Some have a

hydrostatic skeleton Some move through

jet propulsion

Anatomy of Coral

The coral polyps build a calcium carbonate cup called a corallite to live in

Coral has stinging cells called nematocysts

Stinging Cells

Nematocysts help coral catch food

They also help protect the coral

When the cell is stimulated, it releases a sharp barb

The barb will fire and catch the food and bring it back towards the mouth

Coral and Zooxanthella Symbiotic relationship Zooxanthella is an algae that lives in the

skin of coral Coral provides protection Zooxanthella provides food and color!

Coral is Picky

Very specific habitats: Temperature: 73-75F Depth: Less than 80 ft to

230 feet Salinity: Normal salt levels

(35ppt) Light: Zooxanthellae need

light to survive Sedimentation: Being

covered with silt interferes with photosynthesis

Desiccation: being exposed to air. The corals will die if exposed too long

Coral likes areas with lots of waves: They are strong enough to

withstand the pressure Freshwater means more

food Waves remove silt New water brings more

oxygen

Asexual Reproduction

To reproduce coral can reproduce asexually or sexually

Asexual reproduction in corals is called budding

A baby polyp will begin growing off the adult

When it is ready it will detach and live on its own

This can not start new colonies, only help the old colony grow bigger

This is a hydra (cousin to coral) with two buds. One bud (on the right) is older than the other.

Coral Reproduction

Sexual reproduction is called spawning

External fertilization It can start new colonies Sperm and eggs are released

into the water column The fertilized egg is then called

a planula The planula swims until it finds a

good place to live

A New Home

Corals now have a choice of where to live

Corals are very sensitive and are rapidly dying

People are trying to help by creating artificial reefs

Arguments for Artificial Reefs

It can help build or rebuild a reef

It will increase fish populations by making new habitats

Arguments Against Artificial Reefs

Moveable Chemical leaking and

leaching into the ocean It does not increase fish

populations but rather moves them to one location away from their natural habitat which makes them easier to catch