Common names include Mushroom Coral, Disk Anemones, and/or False Coral. These mostly photosynthetic corals are probably the easiest of all corals to maintain because they do better in nutrient rich surroundings. With various size and colored disc-shaped polyps they are very popular. They are not true anemones, nor are they true corals, however, they are somewhere in between or more appropriately, a comparative anatomy or simply put, a morph. They are found worldwide with most in shallow tropical waters.
The taxonomy information that has existed on this group of organisms for a long time has been confusing to say the least. And since I'm not a scientist, and not interested in their DNA/RNA, I've in the past accepted longstanding thoughts as to their classifications. However, recent (2003) revisions by Vincent Hargreaves have resulted in a new rearrangement of this order. It is now said to encompass 3 families (Corallimorphidae, Discosomatidae, and Ricordeidae) and contain 9 genera with 59 species, and is currently shown below.
There are different ways they or the hobbyist can propagate them. In the wild, budding is term used when a new polyp develops on the stalk. It usually migrates onto an adjacent substrate and quickly develops into a clone of the original specimen. Longitudinal fusion is when the specimen splits in half. It usually begins at the central orifice/mouth and extends across the whole disc. Another natural form of propagation is pedal laceration. As the specimen moves over substrate it leaves a small portion of itself attached to the substrate, which grows into a new clone of the original specimen. The hobbyist can simply cut the entire head off the stalk and then cut it into pie-shaped pieces. The pieces can be places in a shallow tray of course sized sand where the individual pieces will attach to substrate particles and form new structures. The cut stalk will regain its original shape, and in the coming months be no different than it was. A loose mushroom containing at least one sand grain attached to its backside can be glued with underwater cyanoacrylate glue to a rock or an aquarium side panel. I've done this and lined the side panels of some aquariums with mushroom corals.
Depending upon where collected, the colors may be more or less pronounced. Colors can range from a solid or variations of colors. Red, purple, blue, mauve, and green seem to be the most popular. Even circular patterns, with green around the outer rim and a deep red inner center have periodically appeared on the market.
Since they all contain zooxanthellae, they can produce the majority of their own food via photosynthesis. Therefore, they do not have to be hand fed, yet iodine additives appear somewhat beneficial. Besides the varieties of colors and textures, their low cost and maintenance requirements make them very popular with most aquarists.
Note to viewers: This family is currently undergoing revisions by Dr. Daphne Fautin of the University of Kansas. When more information is available, it will be posted here.
Amplexidiscus, Discosoma, and Rhodactis genera prefer indirect light and low current areas. If given too much light or become too crowded they will detach themselves and drift around the aquarium, possibly ending up out of sight where they may waste away. All but Amplexidiscus build multi-polyp colonies and have variegated designs and may be combined with iridescent colors.
This genus consists of one distinct species. It gets fairly large, up to twelve inches or somewhat more in diameter. They are generally solitary creatures, however, may be found in small groups. They have small stinging tentacles that are capable of capturing small fishes and invertebrate.
These more common photosynthetic Corallimorpharia members are usually smooth or ribbed with occasional small bumps and are generally small, about one to three inches (2.5 - 7.5 cm). They come in a wide variety of colors and supplement their food supply with absorption of dissolved nutrients in the bulk water. They do better under moderate light, such as fluorescent lamps and prefer gentle water movement and will tolerate some hair algae. Iodine additions are recommended. The red varieties seem to prefer being located in a vertical position, such as on the side of rock. If they are given too much light or become too crowded they may detach themselves and drift around the aquarium, possibly ending up in an area out of sight where they may waste away.
There are now 9 recognized species and 2 others under investigation (early 2004), however, there are numerous morphs making exact identification somewhat difficult for the average hobbyist.
Sometimes called "Elephant Ear Mushroom Corals" because of their larger size. In nature, they are found on reef slopes and in reef shallows and sometimes where the nutrient level is more concentrated, i.e., bays, lagoons, and boat channels. They hail mostly from the Central Indo-Pacific Ocean and do well in a temperature range of about 72 - 83ºF (22 - 28ºC). Their low cost and maintenance requirements make them very popular with reef keepers. They can be fed small pieces of fish/shrimp flesh. This genus has been revised (2003) and now contains 6 species.
Ricordea members have bubble-like tentacles and are usually one to three inches across and have colors that range from dark green to light purple. Some have outer rings of blue/purple/orange. Surface area is covered with short tentacles that can inflate to become bubble-like. These are fairly shallow water members that need strong light and swift water movement, which are requirements opposite that of the other members in this order. There are only two members in this genus.
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