Reefkeeping poses many challenges, chief among them the need to integrate species that live in different natural environments–sometimes thousands of miles apart–and although good reef keepers know to stock only compatable species within a single tank, sometimes even compatable fish and corals need to learn how to get along.
Many people think corals are “plants,” but in reality corals are complex animals (sometimes, colonies of animals). Although they look and behave quite differently from the terrestrial quadrupeds, amphibians, and birds we usually think of when someone says “animals,” corals are animals all the same.
Some corals are photosynthetic, others eat plankton, and others eat larger, meaty foods (including fish — another reason to be careful what you stock in your captive reef). Since corals lack eyes, brains, and complex nervous systems, they react to the environment immediately and without considering consequences. Some sting, while others produce and release toxins. While most of the corals I stock don’t take a toxic approach to unwanted interference, they do withdraw their polyps, “shrink” and show their displeasure when something upsets them.
A difficult situation, since my primary reef inhabitants have a tendency to grab and clutch at everything around them.
But, as it turns out, corals are intelligent–at least in a Pavlovian sense. They can distinguish between an aggressive or dangerous touch and one that means no harm. Without eyes, or brains, or advanced nervous systems, these delicate creatures quickly learn the difference between a seahorse’s tail and other kinds of interference.
They’ve also figured out that porcelain crabs won’t hurt them (though the crabs will pull a meaty dinner right out of a coral’s mouths if they get the chance).
Curiously, the corals had to learn about crabs separately from seahorses. The two don’t feel the same when they grab, and the corals didn’t recognize the crabs as a “friendly touch” at first.
It only takes the corals about a week to stop closing up and shrinking away from these acceptable touches…and yet, even corals I’ve had for years will still close up immediately if I brush them with my hand.
The next time you look at corals, consider: not only are they animals–often carnivorous, and capable of stinging or poisoning intruders in their territory–but corals are also capable of learning to recognize and accept non-threatening creatures in their environment.
An interesting perspective shift, indeed.
Have you ever kept corals, or seen them in their natural environment? What species do you like best?