Tardigrades are microscopic aquatic animals with remarkable abilities to withstand harsh physical conditions such as
dehydration or exposure to harmful highly energetic radiation. The mechanisms responsible for such robustness are
presently little known, but protection against oxidative stresses is thought to play a role. Despite the fact that many
tardigrade species are variously pigmented, scarce information is available about this characteristic. By applying Raman
micro-spectroscopy on living specimens, pigments in the tardigrade Echiniscus blumi are identified as carotenoids, and their
distribution within the animal body is visualized. The dietary origin of these pigments is demonstrated, as well as their
presence in the eggs and in eye-spots of these animals, together with their absence in the outer layer of the animal (i.e.,
cuticle and epidermis). Using in-vivo semi-quantitative Raman micro-spectroscopy, a decrease in carotenoid content is
detected after inducing oxidative stress, demonstrating that this approach can be used for studying the role of carotenoids
in oxidative stress-related processes in tardigrades. This approach could be thus used in further investigations to test several
hypotheses concerning the function of these carotenoids in tardigrades as photo-protective pigments against ionizing
radiations or as antioxidants defending these organisms against the oxidative stress occurring during desiccation processes