The secret lives of coral

While they look like stony and static rock formations to the naked scuba eye, corals are living, dynamic animals with an existence entirely unto themselves.

For decades, Dr. Ruth Gates of the University of Hawaii’s Marine Biology Institute has been diving underwater to peer into the reef and monitor the activity inside and outside its structures. She tells TechKnow correspondent Marita Davison, “when you go out there, you see things of all different heights, different shapes, that’s what a reef is. They are not rocks, they are living organisms.” 

Think of a coral reef like a buzzing neighborhood block with different apartment structures nestled side by side. The apartments are called polyps and they are these fully alive biological structures, with mouths, tentacles, and nocturnal tendencies. Marine life exists within the reef, depending on it as a source of food or a place to duck and cover from floating prey. A trip to visit these watery neighborhoods is a sight for the eyes: corals are stunning, diverse, and thrive in full and vibrant color. 

Lately, these organisms are changing their stripes, transforming their vibrant palates into a pearly white. And that luster is not a good sign. According to Dr. Gates, the white mark is a signal of a deadly shift happening within: “Coral bleaching is actually the change in the color of coral when they go from brown to white. That reflects changes in the basic biology of the system. The breakdown of the interaction between the animal and the plant.”

Dr. Gates takes samples from her ocean field site in LaHaina Hawaii to investigate the coral’s internal dynamics in the lab. She tells TechKnow, “when you look at them very closely as we do with our microscope...you can see that these are very dynamic animals.” 

The microscope Dr. Gates is referring to is a confocal microscope, a specialized tool outfitted with six different lasers that excite the molecule within the coral, revealing their natural florescence. The laser scans from the microscope turn the living coral specimens into works of art. 

The confocal microscope can be used as a diagnostic tool, and is helping Dr. Gates and her team understand what the external changes in color signify about the health of the coral. And while the naked eye would see a white coral and think it’s a goner, the microscope tells otherwise.

This is an example of a bleached coral taken from the reef; it looks totally white on the surface. Yet, when placed under the microscope, there are still residual plant cells there, meaning it still has a little bit of life left in it. 

That tells Dr. Gates that these coral are hanging on for dear life: “Bleached corals when they’re first white yet aren’t dead. They are in this moment in time when they can go in two directions...they can either re-brown [and recover or] if the conditions that are causing the coral to be so perpetuate...that coral will die. There’s no way back.”

Dr. Gates and her team are working fastidiously to condition corals to withstand ocean warming and a changing climate, but time may not be on her side. The trajectory of the health of the reef is on a global downswing, and today, we are facing the potential degradation of all reefs by 2050. 

But for Dr. Gates, this powerful microscope helps show that an otherwise stoic structure has a heartbeat all to it’s own that’s worth protecting.