I used an electron microscope for the first time recently to take a picture of shark skin. I’m not sure why this excited me so much, but I guess it felt a little like the first time I went scuba diving – like I had managed to sneak into a world where I didn’t really belong. As a kid I remember seeing photographs taken from an electron microscope and I always imagined some prestigious scientist, locked in the depths of a high-security laboratory, peering down into the eyepiece of a house-sized microscope and revealing the tiniest secrets that nature had tried so desperately to hide.
Suddenly, I was that scientist – only, without the prestige or the high-security laboratory, and the microscope was only about the size of a computer. And the process was completely different from my schooldays’ experience when I’d throw a sample on a slide, wet it, cover with a cover slip and stick it under a light microscope. No, in fact, the pinky-nail sized sample of shark skin had to be completely dry so it could be glued to what almost looked like a metal thumbtack. Then, I put the skin into a vacuum-sealed machine that performed what I can only describe as a magic trick as it produced electrical current and purple light to cover the shark skin in a microscopic layer of gold dust. That’s right, I had to make gold-plated shark skin in order for this whole process to work! Apparently, anything put into an electron microscope needs to have a metallic surface to produce a proper image.
The microscope fired a focused beam of electrons down onto the gold-coated shark skin, and the electrons then bounced back up into the imager and gave me a look at the bonnethead shark skin magnified large enough to see every detail of the tiny, tooth-like scales called dermal denticles. Amazing! You can’t see it with your naked eye, but these tiny scales are what make shark skin feel rough to the touch. Dermal denticles are one of the defining characteristics of sharks, and I’m using this photograph in my film The Shark Riddle, the newest episode of my half-hour children’s series The Riddle Solvers.