Fig. 1. Patterns of osmolyte distributions in marine animals and mammalian kidneys, shown as estimates of intracellular concentrations. Panels from left to right: (1) sharks and other elasmobranchs are dominated by urea and TMAO (data for Squalus acanthias); (2) shallow-water invertebrates, such as the polychaete worm Glycera, snail Mitrella carinata and clam Saxidomus giganteus, are typically dominated by taurine, betaine and -amino acids (AAs) such as glycine; (3) invertebrates from 2.9 km depth, such as the polychaete worm Glycera and snail Neptunea lyrata, have less taurine and other amino acids and more scyllo-inositol, GPC, and unknowns, while a snail (Depressigyra globulus) from hydrothermal vents at 1.5 km depth has high levels of hypotaurine and thiotaurine; (4) vesicomyid clams (Calyptogena spp.) from sulfide seeps have hypotaurine and thiotaurine and show a depth-related increase in an unsolved serine–phosphoethanolamine solute (Ser-P-Eth-X) and an unknown methylamine; (5) vestimentiferan tubeworms (Riftia pachyptila) from hydrothermal vents at 2.6 km depth have high amounts of hypotaurine and an unknown methylamine, both in vestiment tissue (Vest.) and trophosome (Troph., location of sulfide-oxidizing microbial symbionts), which also has high levels of thiotaurine; (6) mammalian renal cells (inner medulla) have varying levels of sorbitol, myo-inositol, GPC, betaine and taurine (along with urea). Data from Peterson et al. (1992); Yin et al. (2000); Yancey et al. (2002); Fiess et al. (2002); Rosenberg et al. (2003).