When we talk about corals, what comes to our minds might be about its beauty. None of us will ever think about how vicious and fierce they are. However, for small marine animals, the latter characteristics are more likely to be used to describe corals.
Corals are more than ‘living rocks’, they are actually real animals. Their appearance comes from calcium carbonate which is basically their hard skeleton. Thus, no wonder that some of them are carnivore, more than just some herbivore species that most of us are thinking about.
The thing is, corals are actually ones of the most vicious and fiercest carnivores in the ocean. Some corals are known to habitually ‘consume’ bigger marine creatures, although such kind of feast is rarely witnessed by human eyes.
Here, in this article, we will show you that corals are more badass than you think.
To prove that corals are actually predators, here we give you the list of weapons that they use: stinging cells, patience, and good teamwork. Yes, corals can sting their prey using similar stinging cells like what jellyfish own.
But that’s not the main weapon that corals use in hunting their food, instead they use patience and good teamwork more than just stinging the preys passing by. Patience is an important thing to have for them because basically they cannot move.
However, their patience always pays off, most of their preys ‘underestimate’ the power of corals. Even though they cannot move, they don’t need to do the closure. Marine creatures love corals, and that’s why they don’t hesitate swimming close to corals.
Both stinging cells and patience might be effective enough to grant them small marine creatures. But to get larger preys like fish and jellyfish, they need more than those two weapons, and this is when their third and the ultimate weapon comes.
Corals are actually a group of identical polyps living together. When a polyp spots bigger prey, like jellyfish or fish, its opportunistic instinct tells the polyp to just catch the prey. This is when things get interesting, when a single polyp is trying to catch bigger prey, its neighbor will provide help to grab it, providing bigger grab power.
With those three weapons mentioned above, the species that corals can catch varies. Starting from variety of small microscopic organisms such as zooplanktons, to bigger creatures such as small fish and stinging jellyfish.
Corals don’t need to work together to get zooplanktons, they can just eat any number of planktons floating near them by sucking in water. But for bigger preys, the teamwork mentioned above is a necessity.
What’s amazing about this teamwork, every individual polyps participating in the labor will share the catch. Their tiny mouths will tear apart the prey, and then consume the parts they get from the work individually.
Tomas Vega Fernandez and Luigi Musco, from Stazione Zoologica Anton Dohrn, witnessed how orange coral catch and consume mauve stingers, a kind of stinging jellyfish off Italian island of Pantelleria. “I made a signal to Luigi immediately,” said Fernandez.
The researchers then reported what they witnessed to Fabio Badalamenti, Research Director for the Italian National Research Council Institute for Coastal Marine Environment in Sicily. “The jelly tried to move, to escape, but there was no way,” Badalamenti stated.
What’s amazing about the fact that corals can eat jellyfish, is that the stationary creature don’t need to set any trap or attract in a seductive way to get their preys close to them. It is purely based on opportunities and teamwork.
The attack begins when an ‘innocent’ jellyfish swims close enough to the coral to get a grab on its tentacles. Once the polyps get a good grab on the tentacles, other polyps will provide help by getting the jellyfish’s large feeding arms to ensure it cannot swim away.
This kind of coordination is awed by researchers, such as Bert Hoeksema, senior research scientist at Naturalis Biodiversity Center in Leiden, Netherlands. “The coordination among the polyps is remarkable,” Hoeksema said.
However, researchers don’t yet know whether such kind of teamwork is achieved by good communication, or merely built on natural instinct. This is because during the teamwork event, researchers did not notice any signs of communication between polyps.
As the researchers said, the teamwork event occurs without explicit signaling between colonies. Thus, some predicted that the communication only occurs when the colonies are still planning on the attack instead of during the attack.
While researchers are still amazed by how such stationary and tiny organism can eat jellyfish, whose size is as big as the whole coral colony, we have been faced to a problem about the eating habits of the corals.
Just like how some turtles cannot tell the difference between jellyfish and plastic bags, corals are facing the same problem here. Corals live on the floor the ocean, and drowning plastic bag can easily reach them just by following the force of gravity.
When a sheet of plastic bag ‘swims close’ to the corals, most likely the colony will just grab it and start the teamwork event to tear it apart. Alexander Seymour, a geographic information systems analyst and marine researcher at Duke University in North Carolina believed that corals are eating plastic nowadays.
“For years, biologists and conservationists assumed that most sea creatures ate plastic by accident,” he said. This statement was supported by a test that Seymour and his colleagues conducted by giving corals things that researchers predicted they would eat.
When given sands, the corals simply didn’t give any response. But when plastic was given, they found that more than 80% of the plastic were eaten. This is a problem, since corals cannot digest plastic, so the particles of plastic will stay in their body forever.
It shows that plastic poses additional problem to coral reefs all around the world in addition to acidifying ocean and the rise of ocean’s temperature.