After observing zoanthid polyps for years I have noticed that some grow very quickly while others will grow so slowly that if they grow a few button polyps each year then they are lucky. When they have comparable stock sand oral disc size you would assume that they would respond similarly in the same conditions. However, with zoanthids that is not always the case and you never know what you might get! Because of this you will want to pay attention to the zoanthids and document their growth over time to compare them.
Most of the color morphs great at completely different paces despite looking the same and being in the same conditions. Because of this it is challenging to believe that they are the same species that have the exact same needs. When two colonies are identical on the reef and each year one appears to be considerably bigger than the other it makes you wonder whether the difference is just color or if it is an entirely different species.
When this zoanthid color morph appeared in Julian Sprung’s Invertebrates Guide it garnered quite the attention. The specimen had been photographed by Julian before and it is my most recognized zoanthid besides “Perun’s Purple People Eater.”
Of all the specimens I have worked with, this is the fastest growing and most aggressive. I have watched it slowly kill the tissue of a blue Acropora abrolhensis after surrounding it and it began taking over its base. This truly is amazing and totally worth documenting through photos.
The “Actinic Yellow” is the next aggressive zoanthid I have. Notice how it is growing beside a piece of heliopora. This coral is quick growing and can quickly take over everything in the aquarium. The heliopora colony’s growth was kept in check by button polyps.
It was amazing to watch the zoanthid colony defend itself from the heliopora aggression and to begin covering the colony’s perimeter. Heliopora is one of nature’s fastest plating corals. Pay close attention to the zoanthid colony because it will truly surprise you and it is worth paying attention to. Remember, zoanthids may not react the same in the same conditions even if they appear to be the same size. Because of this you truly don’t ever know what you will be getting.