Fig. 2

The gastrovascular cavity oxygen microenvironment of Great Barrier Reef corals. Oxygen microsensor profiles taken inside the GVC of D. favus (a), F. fungites (b), C. aspera (c), and L. hemprichii (d) collected from the Great Barrier Reef. Profiles taken under 650 µmol photons m^− 2 s^− 1 (“Light”) or in darkness (“Dark”). Arrows indicate 100% oxygen saturation under the measurement-specific temperature and salinity. Each profile corresponds to one polyp (mean ± s.d., n = 3 replicate profiles per polyp). (e) Normalised average thickness of GVC oxygen microniches calculated from the profiles in a-d (hyperoxic, normoxic, hypoxic and anoxic). (f) Oxygen concentration ranges for different regions of the digestive tract of vertebrate and invertebrate animals (human, pig, dog, mouse, rabbit, caterpillar, grasshopper, beetle, termite, isopod, sea urchin, sea cucumber, polychaete, L. hemprichii in darkness, L. hemprichii in the light). Data for non-coral animals was calculated from the sources listed in Supplementary Table S3. The exact sections of digestive tract for each organism are listed in Supplementary Table S3 (fore, mid and hindgut are not the technical nomenclature for all animals). For L. hemprichii, we considered three 2 mm thick sections of the GVC (top, middle and bottom). The partial pressure of O₂ at sea level (21.22 kPa) was considered as 100% saturation for measurements performed in air, while 100% air saturation at the measurement temperature and salinity was used for measurements performed in liquid media