Characteristics of Soft Corals

Appearance

• Soft corals come in different varieties based upon their family classification. Every type of soft coral has a fleshy internal skeleton. Corals belonging to the Nephtheidae and Nidaliidae families feature bright colors and branching appendages. Corals from the Alcyoniidae family look like rubbery bumps with retracted tentacles, and only come in muted, neutral colors. Xeniidae family corals pulsate and rhythmically wave their long tentacles, which can be white, brown or blue. Although soft corals are living animals, they have no head and lack nervous, excretory, respiratory and circulatory body systems.

Habitat

• Soft corals are located throughout the world -- most often in tropical reefs up to 30 m deep. Soft corals are prevalent in the Indo-Pacific, the Red Sea, the Caribbean Sea and in the waters surrounding the Hawaiian Islands. Soft corals living in aquariums require generated currents to provide them with oxygen. They thrive best in seawater that is clear, lacks metabolites and has a pH level of slightly less than 8.5. Soft corals also respond positively to 12 or more hours of fluorescent illumination in their tanks.

Behavior

• Soft corals feature stinging cells that defend them from other organisms. They also emit toxic chemicals molecules that poison and deter other species from living too close to their territory. Soft corals can reproduce in different ways, either by asexually budding and fragmenting new individuals, or by sexually producing eggs and sperm. Aquarium keepers can also cut a piece of coral away from its main body and secure it in a new location to artificially produce new corals.

Diet

• All soft coral species eat plankton in the wild. Some species prefer phytoplankton, while others consume zooplankton. Aquarium owners can offer plankton to their corals by suspending their tank's particulate filtration system while directing ground-up plankton onto the surfaces of their corals' tentacles. Soft corals also gain nutritious benefits from chemicals like iodine, which are supplemented into the water. While not all species of soft corals are photosynthetic, some also thrive on light.