Brasil Reef - Fórum de Aquário - Aquarismo - Marinho, Corais e Água Doce

Another example of dramatic elongation of sweeper tentacles is seen in the sweeper tentacles of the Crystal Coral (Galaxea fascicularis). In this coral, normal polyps are only one to two centimeters long while sweeper tentacles have been seen that are 30cm. long. These sweeper tentacles are especially toxic and often clear the area completely of any other invertebrates within the colony's proximity. Therefore, when selecting this coral, care should be taken to provide abnormally wide spacing between it and other corals.

These sweeper tentacles not only appear when a coral is placed in close proximity to another, but they also seem to result when a coral senses the presence of another aggressive coral. I have observed this phenomenon first hand with my Crystal coral. When first placed in my tank no sweeper tentacles appeared during the first three months. However, a Hammer coral (Euphyllia species) was placed in this same tank, the sweeper tentacles appeared within three days. These tentacles also appear to be able to sense where the competitor is located in that regardless of where a Crystal coral is placed relative to the Hammer coral, the sweeper tentacles always develop toward the Hammer coral. Interestingly, the Euphyllia also developed sweeper tentacles, but they were present only on the side nearest the Crystal coral.