Hard Corals, Marine Aquariums and Coral Reef Aquarium Tank, Stand, Canopy, and Aquarium Filter System

Hard Corals

Hard corals are most often referred to as corals that contain a 'hard' calcium skeleton. Their structure consists of a calcium framework, or base, of which a polyp or polyps extend off of. These polyps are generally large ( for the sake of this web page they are ), fleshy and consist of one or more individuals. The fleshy, or bulbous polyps are used for capturing sunlight, as well as, food particles.

A large number of 'hard' corals contain within the fleshy polyp's) a symbiotic algae know as Zooxanthellae. This algae lives within the fleshy tissue and utilizes sunlight via a process called photosynthesis to create a food source for the coral. One of the by-products of the photosynthetic process is that the polyp's) will secrete calcium at their base. It's this depositing of calcium that forms the 'hard' skeleton structure.

In addition to sunlight the coral will also feed on small particles of living matter, dissolved organics and debris's. Most of these 'hard' corals have tentacles that are used for capturing these particles. Some produce the tentacles when they sense food in the water, others only produce them at night. The tentacle is armed with a nematocyst, or stinging cell, that is used to sting its prey or to deture encroaching, competitive, corals.

Because of these corals light and food requirements one needs to provide lighting that is equal to the suns spectrum and intensity ( see the Lighting page ), taking into consideration the depth and turbidity at which the coral normally resides, water current parameters, and its proximity to its neighboring corals.

Purchases of these corals should be subject to inspection of the corals tissue and its even growth over the edges of the calcium skeleton. These corals are subject to considerable damage during shipment and handling. The resulting stress makes them highly subject to protozoan and bacteria infections.

Plerogyra species

Green Bubble Coral,
Plerogyra sinuosa
Bulbous tentacles for capturing sunlight, interspersed with smaller tentacles for capturing food particles. Most specimens sold in the hobby were part of a larger colony.

White Bubble Coral
Plerogyra sinuosa
Bulbous tentacles for capturing sunlight, interspersed with smaller tentacles for capturing food particles. Most specimens sold in the hobby were part of a larger colony.

Pearl Coral
Plerogyra sinuosa
Bulbous tentacles for capturing sunlight, interspersed with smaller tentacles for capturing food particles. Most specimens sold in the hobby were part of a larger colony.

Fine Bubble Coral
Plerogyra sinuosa
Bulbous tentacles for capturing sunlight, interspersed with smaller tentacles for capturing food particles. Most specimens sold in the hobby were part of a larger colony.

Catalaphyllia species

Elegance Coral
Catalaphyllia jardinei
Elongated meandering polyps fringed with tentacles. Most often found in nature partially buried in mud or soft substrates. In general this is a difficult coral to keep.

Euphyllia species

Octopus or Frogspawn Coral
Euphyllia divisa
Individual large polyps with elongated tentacles. Tentacles seem to branch towards their tips.

Hammer Coral
Euphyllia Ancora
Individual large polyps with elongated tentacles. Tentacles tips have a slight 'C' or anchor shape to them.

Torch Coral
Euphyllia glabrescens
Individual large polyps with elongated tentacles. Tentacles are generally straight with a bulbous tip.

Brain Corals

Closed Brain Coral
Favia sp.
Individual polyps forming colonies that are dome or flat shaped. Polyps consist of a central mouth surrounded by a fleshy ring. During feeding numerous tentacles appear around the central mouth.

Closed Brain Coral
Favia sp.
Individual polyps forming colonies that are dome or flat shaped. Polyps consist of a central mouth surrounded by a fleshy ring. During feeding numerous tentacles appear around the central mouth.

Closed Brain Coral
Favia sp.
Individual polyps forming colonies that are dome or flat shaped. Polyps consist of a central mouth surrounded by a fleshy ring. During feeding numerous tentacles appear around the central mouth.

Open Brain, or Meat Polyp
Trachyphyllia Geoffrey
Large, open, fleshy polyp with a wide border. Skeleton is cone shaped. Generally found growing on large gravel bottoms

Spiny Brain Coral
Symphyllia valenciennesi
Fleshy outer margin ( which covers a sharp coral skeleton )

Trumpet Coral
Caulastrea furcata
Individual branching polyps forming colonies. Central polyp is surrounded by a fleshy ring to capture sunlight

Trumpet Coral
Caulastrea furcata
Individual branching polyps forming colonies. Central polyp shown with tentacles extended

Blastomussa
Blastomussa wellsi
Appears as individual polyps but in fact they are all connected

Blastomussa
Blastomussa wellsi
Appears as individual polyps but in fact they are all connected

Tooth, Molar Coral
Cynarina lacymalis
Pillowy outer margins have a semi-clear tissue that shows the coral ridges inside

Cup Coral

Branching Cup, Pogoda Coral
Turbinaria peltata
Skeleton framework is thick and covered with polyps which elongate

Cup, Pogoda Coral
Turbinaria peltata
Skeleton framework is thick and takes on a 'bowl' formation Top, or disk, is covered with polyps.