Anchor Coral Reporduction

Euphyllia ancora

This sequence of photographs shows the asexual reproduction of a branching anchor coral (Euphyllia ancora). The process starts with the formation of a detached skeletal stone or fragment within the tissue located in the coenosteum (mainly the tissue at the outside periphery of the animal). The tissue around this fragment begins to grow rapidly (like a tumor) and the fragment size also increases. Finally, the tissue and fragment weight becomes great enough to cause stretching of the tissue towards the base of the host animal. In time, the sac containing the fragment will stretch all the way to the substrate where, in time, it will fully detach. What follows is my layperson description of what happened when my anchor coral propagated asexually.

The Anchor Coral

I had the anchor coral located up fairly high in the tank for several months, with lots of light and a great deal of wave motion. It was in a high energy situation. Then, I received some Acropora spp. corals and needed this prime space for them, so I moved the anchor down onto the substrate. Here the light was not as intense and the wave motion was blocked to a large degree by the rock work. I believe this change in energy conditions may have, in part, induced the coral to propagate asexually which became apparent 10 days later.

I first noticed something amiss when an area of coral tissue near the skeleton appeared "damaged". It looked like something scraped the tissue in a 1/2" x 1" area. I thought I was going to have to do something to help repair the area but decided to just wait and watch to see if it got worse.

It became apparent that the "damage" was organizing into some kind of structure. Then I realized that the coral was dividing. This has not happened with the anchor coral in over two years that I have had it. The damaged tissue area began to stretch and a small "nugget" of calcium structure was inside of a ball of flesh that was clearly detaching from the host. I was very surprised at how fast this all took place! The picture shows the tissue stretching down by the weight of a small nugget of calcium skeleton. The nugget is still totally enclosed in the extended tissue here shown in the exact middle of the picture. The picture shows the tissue is being stretched farther and the calcium nugget has about doubled in size. We can now see that the nugget is breaking out of the tissue ball where the dark brown area is to the lower right of the ball (exposed skeleton).

This picture shows the tissue stretched to the limit with the calcium nugget about three times bigger than in the first picture and now laying on the sand. Now the calcium nugget is exposed and on the bottom of the tissue ball touching the sand. You might be able to make out several new anchor tentacles to the upper left of the ball! I am tempted to cut the ball away and attach to a new rock but am not sure if this would stress the new born. If I wait for it to detach by itself, the currents may take it under the rocks.

Well the newborn is mounted to a small rock using epoxy putty. The coral is only 1/3" in diameter and you might be able to make out a single tentacle sticking up out of the top. Around the outside is four wafer like structures that make the tissue/skeleton interface (you can see one just in front of the tentacle).

By John Rice