The Corals of the Coral Reefs
Corals of the Coral Reefs
Brian Daniel Eisenberg (Flickr)
Acanthastrea is a genus of stony corals found in the Indo-Pacific. They have large polyps that form huge colonies. These corals are often described as plating corals because of the colonies rounded, flat appearance. The polyps of this coral will only fully extend themselves at night.
Jan Messersmith (Flickr)
Acropora is a large genus of stony corals with over 150 species described. They include staghorn branching, smaller branching, huge table-top, and plating forms. Acropora coloring is dependent on the species and includes various hues of blue, purple, yellow, orange, and red. These corals are important in building the hard substrate that supports and gives structure to reefs.
Blastomussa is a small genus of stony corals with only two species. These corals are not at all aggressive. They rely almost exclusively on the sustenance they receive from the zooxanthellae that inhabit their tissues. They have been observed to filter feed water but will often not need additional food to what they get from their symbiotic partners.
Luke Fritz (Flickr)
(Echinophyllia sp., Echinopora sp.)
These are slow growing encrusting stony corals that develop some incredible colors under good aquarium conditions. They are much coveted by aquarium hobbyists who refer to them as “chalice corals.” Many coral farmers specialize in just these species. They can produce sweeper tentacles to sting their neighbors at night. This is a common feature of many large polyp stony corals as they compete for space on the reef.
This is a genus of stony corals that is highly coveted in aquariums because of their unique structure and shape. Some species of this genus have very long tentacles that are tipped with rounded nubs that look like hammer heads. The color is usually some kind of green although some have striking white or tan accents on the polyps. Euphyllian corals can grow very large.
Luke Fritz (Flickr)
This stony coral genus is also commonly referred to as the brain corals. They are a large polyp stony coral. Corals of this genus are known to be very aggressive especially at night when they will fully extend their tentacles so they need to be kept away from other coral species.
This is an aggressive coral that frequently uses sweeper tentacles loaded with strong stinging nematocysts. It can grow into a very large colony stinging and killing the neighbors that surround it. Sometimes known as the tooth or star coral we will carefully manage this coral and its size as it grows.
Top: Charlie Veron / Bottom: Ed Lovell
This is another very important group of small polyp stony corals. Along with the Acropora corals, they make up the majority of the Indo-Pacific coral species. They come in plating (top photo) and branching (bottom photo) forms, as well as encrusting species that grow over the substrate, rock and even other corals. Montipora colors include pastel browns and greys all the way to bright red, purple and blues with some incredibly intricate patterns and combinations.
This is a genus of stony corals that are commonly referred to as cauliflower or brush corals. They can be either dome shaped or branching and have a wide color variety but the most common colors are brown and pink. It is another coral that will only fully extend tentacles at night. This is a fast growing coral that can have aggressive tendencies towards corals of other species.
Seriatopora corals are sometimes called bird’s nest corals because they are so thin and delicate. They will form large colonies that can look like bushes. The most common colors are yellow, pink, brown, and tan. Seriatopora usually only extend their tentacles fully to feed at night.
This is another small polyp stony coral that has a distinctive pink or light purple coloring. This coral has a very strong skeletal structure that is resistant to fracturing.
Black Candelabra Gorgonian
Black Candelabra Gorgonians are a photosynthetic type of coral that is characterized by its striking black coloring. It is long, thin, and branching along a parallel plane. This type of branching gives the coral a similar appearance to candelabra giving it its namesake. If it comes into direct contact with Gorgonians of another species it has been known to show interspecies aggression. This species is able to regrow after fracturing, meaning that if a piece of the larger coral is taken, it can be cultured and grown to maturity.
Paul Asman & Jill Lenoble (Flickr)
Diploria Brain Corals
(Diploria clivosa, Diploria strigosa, Diploria labyrinthiformis)
Brain coral is a common name given to many species of stony corals throughout the tropical oceans. The species on display in this system are all from the Caribbean. These corals are important reef building stony corals classified as endangered and protected by CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora). They get their common name from their round shape and grooved surface resembling a brain.
Anemones are close relatives of corals, both being in the Cnidarian phylum. This is not a type of anemone that Clownfish would inhabit, but some shrimp and crabs do live in them. Anemones help filter the water in the tank but they also have a sting that they use for defense and to capture food. They have been known to eat shrimp and other small invertebrates in tanks. Additionally, these creatures are mobile. They have “feet” and are able to walk around the tank.
Golden Plume Gorgonian
Golden Plume Gorgonians are a branching gorgonian with striking yellow or gold coloring. They have a single main axis with branching feather-like limbs and can also grow up to 1 meter (3.2 feet) tall in the wild. This coral cannot come into direct contact with Gorgonians of another species because it will exhibit interspecies aggression.
Hazel Eunice Gorgonian
Hazel Eunice Gorgonians are vertically growing corals that have few branches. They are usually a brown to tan color. These Gorgonians look like they have a fuzzy texture when the polyps are extended because it is made up of rougher tissue than its close relatives. This coral cannot come into direct contact with Gorgonians of another species because it will exhibit interspecies aggression.
Lavender Bottlebrush Gorgonian
Lavender Bottlebrush Gogonians are compact and have arms that can branch in every direction. This characteristic helps to distinguish it from the very similar looking Purple Plume Gorgonian. It is sometimes compared to an underwater Christmas Tree. This coral cannot come into direct contact with Gorgonians of another species because it has been shown to exhibit interspecies aggression.
(Montastrea cavernosa, Montastrea faveolata)
Montastrea corals are another important group of reef building stony corals. These corals form some of the largest coral colonies on the reef. They can form massive structures of several feet across. As with all Caribbean stony corals they are considered endangered and are protected species.
These small corals look like anemones since they do not have a calcium skeleton but anatomically they are much more similar to soft corals. They are correctly classified as belonging to a group of corals known as Corallimorphs. They come in a range of bright yellow, green, orange and blue colors and are peaceful corals although they have the ability to compete for space with others.
Purple Candelabra Gorgonian
Purple Candelabra Gorgonians are very similar to Black Candelabra Gorgonians with the major difference being the rarer purple coloring. The polyps are a cream color making them easy to distinguish from the Gorgonian tissue. These corals branch on a parallel plane making them similar in appearance to candelabra, giving them their name sake. This coral cannot come into direct contact with Gorgonians of another species because it will exhibit interspecies aggression.
Purple Plume Gorgonian
Purple Plume Gorgonians are similar to Golden Plume Gorgonians. They have a single central axis with many secondary feather-like branches that split off the center stem. The polyps are very small and tan in color. In the wild, these corals can grow up to a meter (3.2 feet) tall. This coral cannot come into direct contact with Gorgonians of another species because it will exhibit interspecies aggression.
Zoanthid Colonial Corals
Zoanthids are a large group of corals that are most recognizable for their bright colors and flower like appearance. The large polyps can be observed in our tanks but depending on the time of day, they may be closed. Additionally, if a fish or other organism disturbs these corals, they will quickly close up their polyps as a defense mechanism. These corals are thought to contain what can be a fatal toxin called Palytoxin. If this toxin is introduced to an open scrape or wound on human skin it can be quite dangerous.
General Comments on Inter-Species Aggression and Protection by Steve Lowe, our aquarist
Corals are typically immobile animal colonies. There are exceptions to this with anemones and some corals capable of relatively slow movement but all are potentially vulnerable to predation simply because of their inability to easily avoid animals that may want to eat them. Typically stony corals only reveal their soft tissues at night when the coral polyps open up to feed on zooplankton. During the day, they use their hard coral skeleton to protect the polyp from browsing fish such as many butterfly fish that prey on corals. As encountered with terrestrial plants and some insects and animals, a common alternative to protection is to produce chemicals that are toxic to predators or at least “make yourself unpalatable.” Across the soft and stony coral species, we are starting to learn of some unique and highly evolved means of chemical and biological defense. Complicated organic molecules are being discovered that are linked to the defense system of many corals and other marine invertebrates. Some of these chemicals are also used to compete between species for space. Analogous to trees growing in the forest, there is competition for sunlight to fuel their biologic processes and so many corals are observed to attack each other when they sense each other’s presence.
Of increasing interest is investigating the chemicals produced by corals and other marine animals to help cure human disease. Many of these biologically active chemicals have the potential for helping design drugs to treat cancer, pain, neurological, cardiovascular diseases and other difficult to treat ailments. There are 18 drugs based on chemicals found in the marine environment currently in clinical trials and hundreds more identified as having pharmaceutical potential. The risk to this pipeline of disease-curing drug discovery is of course the loss of the very animals that produce them and the environment they live in.