(a) δ13C and δ15N (mean and standard deviation) of taxa and tissues analysed from Longqi vent field, Southwest Indian Ridge. (b) Specimen of Chiridota sp. collected from Longqi. (c) Specimens of Neolepas sp. 121 collected from Longqi. (d) Specimen of Bathymodiolus marisindicus collected from Longqi; also visible is the commensal polynoid polychaete “Branchipolynoe sp. ‘Dragon’” (stable isotope composition not analysed).