85-6 Wednesday, Jan. 6 11:30 The limits of an invisibility cloak: transparent shrimp become opaque after multiple tail-flipping escapes BAGGE, LE*; KINSEY, ST; JOHNSEN, S; Duke Univ.; Univ. of North Carolina Wilmington; Duke Univ. email@example.com
Whole-body transparency, an apparently effective camouflage strategy in many aquatic species, can be disrupted by environmental/physiological stressors. In this study, we found that tail-flip escape responses temporarily disrupt the transparency of the anemone shrimp Ancylomenes pedersoni. After as few as three tail-flips, the previously transparent muscle fiber bundles within certain regions of the shrimps’ abdomens become visibly opaque. Eliciting additional tail flips to the point of exhaustion (16 ± 3 SD; n=23) resulted in further increases in opacity, though the original transparency returned after approximately three hours of recovery. We hypothesize that increased perfusion, or an increase in blood volume between muscle fibers, can disrupt the normal organization of tissue, creating regions of low refractive index fluid between high refractive index fibers, resulting in increased light scattering. Our study measures pre- and post-contraction perfusion via (1) the injection of Alexa Fluor 594-labeled wheat germ agglutinin (WGA) that labels the sarcolemmal areas in contact with hemolymph, and (2) the injection of 0.2μm fluorescent microspheres that remain in the smallest perfused spaces. Additionally, we use transmission electron microscopy to quantify ultrastructural changes in the muscle tissue that becomes opaque after exertion. Comparing sections of opaque and transparent muscle tissue from this transparent shrimp species, as well as comparing the shrimp tissues that become opaque after exertion with tissues from a previously studied, non-transparent shrimp species, will help us understand how transparency can be disrupted.