Open Brain or Pacific Rose Coral is amongst the easiest to care for, most appropriate true or stony coral species available to marine aquarists. Given selection of initially healthy specimens, moderate light, water movement and decent water quality this it ranks near the top in terms of hardiness.
According to current taxonomists, popular and scientific there is just one species in the family, Trachyphyllia geoffroyi... with Wellsophyllia radiata Pichon 1980, the Pacific Rose Coral a nomen nudum. The latter name is (unfortunately) still used in the ornamental aquatics field... in fact, at times mis-applied to the Tropical West Atlantic Manicina areolata Linnaeus 1758, Caribbean Rose Coral, aka Caribbean Brain Coral.
All these "Open Brains" are flabello-meandroid in overall structure (something resembling a squashed dome as adults), solitary to colonial, hermatypic (reef-building) with large, numerous septa. The monotypic Trachyphylliidae is divided from the similar family Faviidae on the basis of its skeletons large paliform lobes and small teeth on the septa. Details of macro and ultrastructure of these species are most easily found in Veron's tomes listed below. A previously utilized characteristic for discerning Wellsophyllia was its fused (versus separate in Trachyphyllia) meandroids.
As can be seen, Open Brain Coral has large polyps with a mantle that can be expanded more than three times the size of its skeleton during the day. Generally this is a nocturnal feeder, producing rows of tentacles to capture prey by the dark of night. You can see the numerous mouths in the colonies valleys at this time.
Found widely in the Indian Ocean including the Red Sea, throughout the Australasian Archipelago, mainly on sandy to silty bottoms on coastal reefs. Reddish to brown founds found in murkier or deeper waters.
Up to eight inches or so in diameter in captivity, with their fleshy polyps at times extending two-three inches beyond.
Ideally, a full-blown reef set-up with either boosted fluorescents and/or MH if more than a couple of feet deep. Finer substrates are better, but I've seen these animals kept on bare bottoms, gravel, mud (in public aquariums around the world). In the wild they utilize their fleshy expansion to lift themselves (including their carbonate skeleton) to cleaner, sunnier conditions upward.
Open Brain Coral are best just placed (gently) on the aquarium substrate, though they can be positioned on a flat area arranged in your rockwork. Take care (of course) to not tear the animals tissues. By waving your hand near an open specimen, it will retract its polyps facilitating its moving.
Types and amounts of lighting are not ultimately too important with this species. They will/do adapt, even change color readily to suit the circumstances afforded them. Do however guard against photo-shock in the case of placing new specimens and changing aged lamps.
Standard reef conditions of biomineral and alkalinity concentration range, medium to intense lighting, low water motion suit Trachyphyllia. Initially healthy and acclimated specimens are very sturdy.
Irrespective of their natural inclination (often found in muddy to polluted circumstances) or tolerance, Open Brain Corals should be kept in clean water... physically and chemically. Have seen all filtration schemes used with this species (this was/is one of the earliest, most popular species kept in the sixties... and on) with good success.
I suggest no more than twice weekly feedings of Open Brain Corals... other authors/aquarists only advise one or two times a month. Meaty foods (fish flesh, crustaceans, shellfish) or chunky size can be placed at night right on the animals tentacles. Still other writers and hobbyists apply or rely on their systems, refugiums to produce sufficient planktonic food for their Open Brains... I encourage you to expressly feed yours.
Have been seen to asexually reproduce in captivity by budding of small pieces breaking off a mother colony.
Things to look for in assessing the health of Open Brain specimens are the regularity and degree of expansion of their polyps, tissue pulling off the skeleton, and bleaching. If this occurs within a short period of time, it is likely that either some other stinging-celled animals influence or water quality are involved. Biomineral content (Calcium, Strontium, Magnesium) AND alkalinity need to be checked and if necessary, adjusted, and excess nutrient accumulation (nitrates, phosphates) guarded against.
Should these conditions evidence themselves over an extended time frame, perhaps your lighting is to blame (check the inception dates for your lamps). This species responds favorably to iodine additions to its water as a general cathartic, as well as a regular supplement practice.
Adapting to a wide range of lighting, water motion and quality, Trachyphyllia is an ideal "starter" or "beginner" stony coral; likely the hardiest of stony/true coral species in aquarium use. Happily it is an abundant/common, easy to collect species in the wild with a distribution range matching its usefulness to aquarists.
Erhardt, Harry & Horst Moosleitner. 1997. Marine Atlas 2 Invertebrates. MERGUS, Melle, Germany. p. 439.
Fatherree, James W. 2000. The Open Brain Corals. TFH 2/2000.
Fossa, Svein A. & Alf Jacob Nilsen. 1998 (1st ed.). The Modern Coral Reef Aquarium, v.2 (Cnidarians). Bergit Schmettkamp Verlag, Borhheim, Germany. 479pp.
Humann, Paul. 1993. Reef Coral Identification; Florida, Caribbean, Bahamas. New World Publications, Inc. Jacksonville, FL. 239pp.
Vargas, Tony. 1997. Feature Coral: Trachyphyllia geoffroyi. FAMA 9/97.
Veron, J.E.N. 1986. Corals of Australia and the Indo-Pacific. U. of HI press, Honolulu. pp. 537-539.