From Eric Bornemann
Sweeper tentacles are specialized tentacles that extend further than the other normal feeding polyps of a coral. There are many corals which seem to possess this capability, but Euphyllia is conspicuous. The sweepers are noted for having more numerous and powerful nematocysts, which allow them to adopt a very powerful aggressive or defensive posture relative to other corals. Because of the intense competition for space on the reef, many corals have adopted methods by which to "stake a claim," and allow room for growth and expansion. These specialized tentacles are very adept at this purpose. Not only do the Euphyllia species form sweeper tentacles, they can form many long powerful sweeper tentacles. Oh sure, Galaxea is known for its sweeper tentacles, but those are mere long thin threads. The sweepers on Euphyllia and like spring loaded jack hammers. They can extend outwards up to 8 inches or more from the rest of the tentacle mass. If these tentacles come in contact with other corals, the nematocysts are numerous and strong enough to allow the end of the tentacle to stick to a nearby coral and remain there, causing significant localized damage. In fact watching a sweeper attach and kill a neighboring coral is similar to a lethal injection , with the coral pumping the nematocyts' poison like a deadly slow drip IV line into anything close enough to reach.
It seems that any tentacle can differentiate and adopt this specialized form.
Despite some reports that merely taking a scissors and snipping of the sweepers is an effective way to get rid of them, it has been my experience that this is a temporary and fruitless endeavor. More sweepers will be formed in their place, and consistent snipping of living tissue always poses a risk of losing the coral to a resultant infection. Therefore, I feel the best solution is to place any Euphyllia species well out of contact range with any other corals. It may be noted, though, that with the exception of E. glabrascen s, all Euphyllia species may be placed near each other, as they do not seem to have any negative interactions between species.
Captive reproduction of most Euphyllia species is by budding of daughter colonies around the base of the parent or by separation of a colony from the living tissue edge around the septa. Sexual reproduction occurs in the wild, and has been documented in captivity, as well.
