The Branching Hammer Coral, Euphyllia ancora is a large polyp stony (LPS) coral that gets branches like a Torch coral (E. glabrescens). Also called the Euphyllia Hammer Coral or Anchor Coral, its common names are derived from the hammer like, anchor-shaped tentacles. The Hammer Coral polyps are visible throughout the day and night and hide its skeletal base. The polyps may be gold, green, tan, or brown in color, with lime yellow or green tips on the ends of its tentacles that glow under actinic lighting.
Aggressiveness They have potent sweeper tentacles that it will send out to other corals to keep them from growing too close and will sting anything within reach with its nematocysts. Because of this, you should take care to ensure that your coral has enough room both now and in the future, once the corals in your tank have begun to fill-in the available space.
In terms of water flow, these corals prefer a moderate water flow. Too large a flow will cause the polyps to retract, or be damaged and may also encourage sweeper tentacle issues (see below for more information about that).
Since Hammer Corals are found in shallow water regions on the reef it requires moderate lighting levels (from PAR 150-250). T5's, Metal Halides, or LED's can all grow Hammer corals when the proper PAR levels are provided. We recommend a 14-20K color spectrum for best coloration. A warning on using high output lighting; if it will be exposed to brighter lighting it needs to be acclimated to the high output lights in the tank slowly, as it is not usually exposed to intense lighting in the ocean because of its depth. Start out with low lighting, positioning the polyps to face out (versus upwards) and have it shaded by rock or something within the tank. The lighting can gradually get stronger over time, but make the changes very slowly.
A mature, well-fed live rock/reef environment is what is needed, along with some fish for organic matter production, and dissolved organics. Best location is on the bottom of the tank.
Diet and Feeding
It is not necessary to feed a Hammer coral, although they are capable of eating fairly large (by coral standards) meaty foods. The fact that they are biologically able to consume rather large, meaty meals, suggests that feeding should be strongly encouraged. However, Euphylia glabrescens could be kept successfully in a reef tank without any feeding at all, as long as adequate lighting is provided, because their symbiotic zooxanthellae will sustain them. If you want it to grow faster I suggest you feed your corals. All of them. Your Hammer coral will feed nicely on frozen mysis, fortified brine shrimp, rotifers, Cyclopeeze and other similarly sized meaty foods.