The past few years stone corals with small polyps from the genus Acropora, Montipora, Pocillopora,en Seriatopora receive more and more attention of the owners of reefaquaria. Less frequent specimen from the family of the Pectiniidae in which the genera Mycelium, Echinophyllia, Oxypora, Physophyllia and Pectinia belong are me , which without doubt will be connected with the larger depth from where the organisms originate. To identify them is rather difficult question, because, excepting the Pectinia, that never has a discoid appearance, the animals strongly resemble each other in their tin palle like growth.
Feeding :
1. Symbiotic alga(zoöxanthells) This live in the (inner one of the two body walls). Their number may vary, depending on the strength of lighting, from 100.000/cm till 10.000.000/cm2 and depends of the species of the corals and the intensity of the lighting. Between the zoöanthells and the animal tissue of the host there is a flow of material and energy. These complete each other on perfect way. Photosynthesis and breathing have been liaised on the level of the cells, by wich these flows can take place practically without loss.
2.Endolitic alga.In addition to the zoöxanthells stony corals have a second photo-autotrophe source of food. In the skeleton of quite a lot of species with an without zoöxanthells as well live red and green alga Between this drilalga and the coral skeletons there is taking place

an exchanging of substances that can be compared with the exchange as is described above.
3 All sorts off particles of food coming from outside. The supply of this nutrients on the reef is abundant and encloses bacteria, larger zoöplankton and particles of vegetable origin and of animal origin in the most divers sizes as well.
................Depending on the depth the supply of this changes in qualitative and quantitative way; In the upper layer of water takes place the primary production of the plankton, by what a larger supply of zoöplankton is involved. The more the depth increases and the intensity of light decreases the importance of 1 and 2 will decrease and that of 3 will increase. Here we often see tentacle lesss corals with a discoid shape at which the mouth opening(s) are at the upper side. The transport of the received food takes place than with the aid of the ceilia (a kind of flagellum's ) that make, often through grooves, "stream" the food to the mouth opening It concern particles of food that are not of any interest for the predators because it takes to much energy to capture them in sufficient number and that sink down therefor. With other corals that don't have Celia where distinct grooves are lacking, the particles are instantaneous wrapped up in slime and transported to the moth opening (Mycedium elephantotus)
Who wants to know more about the extreme interesting way of life can read more about it in Datz 1999 no 10, 11 en 12 en 2000 en Aquaristiek Fachmagasinvan de Tetra Werke jaargang 33 no 1