Octocorals
Soft Corals
Soft coral is also known as Alcyonacea and ahermatypic coral, which is a type of coral that does not secrete calcium carbonate skeleton or forms reefs. They are normally colorful and look like underwater plants that swing with the wave in the ocean. They are colonial, and often times little polyps combine together to form a large organism.
Structure and Biology
Soft corals have sclerites, which is a spiky skeleton element that soft coral secretes that supports their vertical structure as well as give them texture. They also has gorgonin in the inner core of their colony, which is a type of fibrous protein that enables the flexibility of soft corals and their swinging movement along with the ocean waves. Their polyps are anatomically different. [1]
Suborders
| Alcyoniina |
| Calcaxonia |
| Holaxonia |
| Protoalcyonaria |
| Scleraxonia |
| Stolonifera |
Distribution and Habitats
Soft Corals can be found in waters world wide; however, primarily exist in tropical or subtropical climates. They are typically found in intertidal zones. Some are found in deep sea, at depths up to six hundred and fifty feet or more. [2] Soft corals exist on inner reefs just below the stony corals. They are not often the dominant corals within the reef, inhabiting dim areas such as caverns. Soft corals are easily collected from the wild and most will thrive and grow quickly in captivity. Because of this, soft corals are popular for domestic aquariums.[3]
Behavior
Soft corals can feed during the night or day. They are most known for getting their nutrients from multiple sources such as symbiotic relationships, planktonic organisms, microscopic food particles in the water, and dissolved organic matter. Many soft corals obtain the largest portion of their nutrients from symbiosis with the marine algae, zooxanthellae. Some also have stinging cells, nematocysts, that sting passing organisms like plankton. [4] Soft corals that are kept in captivity will thrive well being given plankton or brine shrimp.
Soft corals are known to often change forms so to adapt with water flows and types of prey. Some species, like the Xeniidae family, are known to exhibit a 'pulsing' motion. This happens when the polyps retract, extend, and retract again on the surface of the coral in order to capture prey.
Soft corals have a chemical defense mechanism to ward off predators and other species that may harm them. They have allelopathic (toxic to other species) chemical effects; terpenoids and other molecules that poison creatures that wander onto its surface or try to attach onto the corals. They chemicals can be released into the water.
Reproduction
Soft corals are able to reproduce sexually or asexually. They sexually reproduce when the corals release sperm and egg in a mass all together as a fertilizing event (brooding). The sperm that is released is gathered by female polyps that have eggs. When the egg and sperm fertilize their larva, it eventually settles to the bottom to begin life cycle. Soft corals asexually reproduce by budding and fragmentation. Budding is when a new polyp develops out of a previous one. In fragmentation, a large healthy portion is cut away from the organism and allow to start growing and developing independently. Soft corals in captivity can be artificially propagated using the process of cutting and grafting. This involves cutting a reasonable piece of the coral off, soaking it in a sterile solution and attaching it with a kind of glue to a hard substrate. The coral will then adapt and grow on its own.
Human Influence
Soft corals are at danger from humans for reasons of disturbance, over harvesting, habitat destruction, and pollution. Soft corals are harvested for recreationship purposes such as personal and commercial aquariums, and for medical purposes. The tissues can be compounded to form medicines. Soft corals draw in a lot of tourism, which is a threat because of people stepping on and damaging the corals.