A Non-Invasive, Label-Free Method for Examining Tardigrade Anatomy Using Holotomography

Holotomography is an advanced imaging technique that enables high-resolution, three-dimensional visualization of microscopic specimens without the need for fixation or staining. By applying this technology, we successfully imaged live <i>Hypsibius exemplaris</i> in their native state, avoiding invasive procedures and phototoxic effects. Using a low concentration of 7% ethanol for tardigrade sedation and sample preparation, we captured detailed, label-free 3D images of both external and internal structures, including the digestive tract, brain, ovary, claws, salivary glands, and musculature. These findings highlight holotomography as a complementary high-resolution imaging modality that effectively addresses challenges faced with traditional imaging techniques in tardigrade research.