Botryllus schlosseri was a challenging colonial to capture under fiber optic lighting. The variants with dark-colored zooids blended in with the backgrounds making difficult the photography of structural detail. With the light color variants against a darker background, the two-toned beige, which formed a mosaic-patterned colony, and single-colored orange colonies proved to be highly photogenic.
To capture the zooids with open siphons, I tried Gretchen Lambert's technique for relaxation with menthol crystals. It was terrific for relaxing ascidians as well as other invertebrates. But as with any approach, I found relaxation had its pros and cons for viewing as well as photomicrography. Relaxation greatly reduced contraction ability, but also inhibited the ability of zooids to fully expand. Lack of anesthesia was challenging under bright light because individual zooids reacted to the light independently, each zooid in a cluster randomly closing and re-opening during photography. My objective was to obtain images where all the branchial siphons in the field of view were fully open. It made for some interesting and entertaining time-sequence shots.
The images below are two of my favorites. They demonstrate the difference between the information revealed capturing images of light vs. dark Botryllus color variants and show zooid structural and pigment cell details that cannot be seen solely by underwater photography. The 40X original magnification generated images with the greatest resolution and zooid detail (4X zoom + 10X objective lens). These details can also be seen out in the field with the 30-40X jeweler's loupe magnifying glasses that I discussed in the Nov. 25 Post. The beige variant gave vivid zooid detail, whereas the typical white star on dark purple was outstanding for showing cells in the pigment bands.
Botryllus schlosseri White Star Variant with Parallel Pigment Bands.