Looking at tardigrades in a new light: using epifluorescence to interpret structure

Summary The use of epifluorescence microscopy coupled with ultraviolet (UV) autofluorescence is suggested as a means to view and interpret tardigrade structures. Endogenous fluorochromes are a known component of tardigrade cuticle, claws and bucco-pharyngeal apparatus. By imaging the autofluorescence from tardigrades, it is possible to document these structures in detail, including the subdivisions and boundaries of echiniscid (heterotardigrade) plates and the nature and spatial relationships of the texture (pores, granules, papillae and tubercles) on the various plates. This allows the determination of taxonomic features not easily seen with other microscopic techniques. Lay Description Here we describe the advantages of using UV autofluorescence to image the cuticle, claws and buccopharynx of water bears or tardigrades. Tardigrades are identified by their cuticle's surface, the shape of their mouth and buccopharynx, and the size and shape of their claws. Because the cuticle autofluoresces in proportion to its thickness, this method can tell pores and bumps apart when other light microscope techniques cannot. Some tardigrades, known as echiniscids, are armor-plated on their backs. These echiniscids are separated by the texture and shape of these plates and cannot be identified unless we know if a pore or a bump is present. Thus UV autofluorescence is a very useful tool for anyone wishing to look at tardigrades.