Jenga and Giants

I was barefoot and wet. The sun beat down on my shoulders, the concrete toasted the soles of my feet, and water from the hose splashed up to my knees. One by one, I rinsed clear plastic containers and stacked them to dry. Every piece of plastic that had a chance of touching coral gametes had to be soaked in seawater, rinsed in freshwater, then left to dry in the sun. To save space, I stacked the containers, and I turned each one 90 degrees to allow airflow from below. It looked like a game of Spawning Jenga. 

Building my Jenga towers with clean spawning containers. 
Photo by Maikani Andres.

I finished stacking the containers right before lunch, so we each guessed how many of the towers would still be standing after our break. I guessed all of them - so confident was I in my design. Matthew guessed all but one - he could see one of the towers swaying in the breeze. Maikani didn't make a guess, but she should have made a wager because she would have been right. Three minutes before we returned to the tank room, a light breeze blew over that one unstable tower, which set off a domino effect and scared the daylights out of an aquarist. Oops. 

We had essentially finished cleaning and organizing our spawning supplies by mid-afternoon, so our focus shifted to gametes themselves. The aquarist afflicted by our toppled towers was actually spawning giant clams today, so we got to observe the process. He induced the clams to spawn by injecting serotonin - exactly the same method I had used for deep-sea mussels in grad school. I was highly amused to discover that bivalves everywhere responded to the same spawning cue. A few minutes after the injection, the clams started releasing sperm and turning the water in their bins milky white. It was really cool to see. 

Giant clam sperm photographed using a phase-contrast 
microscope. Photo by Matthew-James Bennett.

The clam sperm actually served a great purpose for us, because it let us test a new microscope. I bought a phase-contrast microscope for our team to use this trip because it is the best way to visualize sperm. Phase-contrast is a method of converting phase shifts in a light wave to amplitude variations that can be perceived by the human eye. In other words, phase-contrast allows you to see structures that have similar transparency but different consistencies. If you're just looking at a cell under a microscope, every part of that cell might be clear and therefore very hard to see. With phase-contrast, parts of the cell that are made up of different molecules and have different densities show up as brighter or darker, so you can actually see them. Phase-contrast is the best way to see sperm under a microscope, but I had never used one before. 

We definitely wanted to know what we were doing with the microscope before our precious coral sperm showed up - and that's where the giant clam sperm came in. Matthew spent several hours fine-tuning the microscope settings and trying to resolve the sperm as well as possible. He made a lot of progress. We're not quite there yet, but we should at least be able to get some decent pictures once our corals spawn. 

It was a productive day in the lab, and I'm really looking forward to coral spawning!