Back in 2017 at Friday Harbor Laboratories, in between conducting experiments on transgenerational responses to pH in the copepod Tigriopus californicus, I tried scanning electron microscopy (SEM) for the first time. I wanted to explore fine morphological details of the copepod, to look for differences among San Juan Island populations and cultures that had been reared under different pH conditions.
Since that summer, the images have been sitting on my computer. I am not satisfied with the quality of most of them- it was not possible to discern morphological differences among samples of copepods. I tried two methods to prepare samples: a glutaraldehyde and osmium tetroxide protocol (a time-consuming and nasty process that wasn’t worth it, or necessary to visualize exoskeleton, in retrospect), and another using an ethanol series and HMDS for drying (not great, but actually worked better than the first). In the future, I want to try different preparations and fixing protocols to achieve better results. Common issues were cracking and wrinkling of the exoskeleton, and lots of debris tangled in the swimming appendages and mouthparts.
I recently looked through the images again, and realized that some of them look pretty cool, despite the issues I was having with sample preparation. Rather than keep them hidden forever, making all of my work a waste, I thought it would be better to get over my insecurities and share them here!! If anyone has tips for preparing small crustaceans for SEM that they are willing to share, I would really appreciate it.
Thank you to the following sources of support for my research in 2017:
- The American Microscopical Society
- Sigma Xi Grants-In-Aid of Research
Stony Brook University, Ecology & Evolution Department, Graduate Student Excellence Award
I am also grateful to Matt Kolmann, Mike Temkin, and Billie Swalla (and many other wonderful colleagues at FHL) for help with troubleshooting as I was learning to use the critical point dryer, sputter coater, and SEM.