Hologram Hammers

Hammer corals are found all over the tropical waters of the Pacific. In particular, they are regularly harvested from the islands of the Indo-Pacific including Fiji, Tonga, Solomon Islands, and the Great Barrier Reef.

Like most coral, Euphyllia rely to a large extent on the products of their zooxanthellae, however, in our experience, they also benefit from direct feeding. Hammers, torches, and frogspawn do not seem to aggressively feed like other LPS, so finding the right food can be a challenge.

WATER CHEMISTRY

Hammer corals require consistent levels of calcium, alkalinity, and to a lesser degree magnesium in order to grow their calcium carbonate skeletons. The amount of supplementation needed to maintain calcium, alkalinity, and magnesium depends a lot on the size and growth rate of the stony corals in your tank. Higher densities of stony corals consume these compounds at a faster rate than sparsely populated aquariums.

There are many ways to successfully manage calcium, alkalinity, and magnesium levels in the home aquarium. In the video below, I cover three different aquariums that utilize different techniques to manage their chemistry.

gonizing over these levels might be mental overkill for hammer corals, but it is good to periodically test just to make sure everything is in the ballpark of natural sea water levels. A couple parameters worth paying closer attention to is nitrate and phosphate. LPS corals are sensitive to declining water quality and elevated levels of nitrate and phosphate are an indicator of declining water quality. Low nitrate levels around 5-10ppm are actually welcome for large polyp stony corals, but around 30-40ppm of nitrate you might start running into some issues such as tissue recession. In extreme cases, you might see a torch coral go through full-fledged polyp bailout which we will cover later in this article.

PROPAGATION

Hammer corals for the most part has been propagated extensively in captivity and is an excellent candidate for aquaculture. One possible issue preventing wide-scale commercial aquaculture is the fact that hammer corals do not grow very fast compared to other stony corals. The branching varieties tend to be much better candidates compared to the wall varieties. Hopefullyt a sustainable harvest can be achieved in time.

There is however a much less common method which is polyp bailout. Polyp bailout is a stress response to unfavorable tank conditions that certain stony corals can activate as a last ditch effort to save themselves. During polyp bailout, polyps are killing off their own connective tissue through apoptosis. For those that are unfamiliar with the term, apoptosis is programmed cell death as opposed to necrosis which is traumatic cell death. Apoptosis is a highly regulated and controlled process so the coral polyps bailing out due to stress are doing so in a direct calculated response to an exogenous threat.

HAMMER AGGRESION

Corals developed all kinds of adaptations to gain a competitive advantage in the battle for real estate on the reef. In our home aquariums we have to be conscious of these in order to create the best environment for them long term. Euphyllia are one of the corals that extends long sweeper tentacles. Sweeper tentacles are often used as a means of defense against other encroaching coral colonies. Their white tips contain a concentration of nematcysts that can damage more delicate tank mates. Most of the time, this is not a major problem but to be safe, we recommend placing it in a location far from other corals initially.

The video below provides an overview of the different manifestations of coral aggression and ideas on how to mitigate some of the risks inherent in keeping corals in close quarters.

ACCLIMATION

Proper acclimation is extremely important considering the stress imposed on the animals by the shipping process. Please take a moment to review our Acclimation Guide.