under varied illumination angles, wavelength, substrate composition, bacterial seeding, and index matching conditions. Combining experiments with ray-tracing simulations, we show that scattering arises from two interacting components: volume scattering within the body and surface scattering at interfaces between the worm and its surroundings. Surface scattering dominates at low angles and enhances animal boundaries, whereas volume scattering becomes more prominent at higher angles and improves v