Gas mass fraction within r_gal as a function of the rotational-to-total kinematic energy parameter, κ_rot. The left-hand panel corresponds to EAGLE, right-hand panel to TNG. Symbols show individual galaxies coloured by morphology: Red circles indicate early-type (E); blue spiral symbols denote late-type (S); grey squares are used for all others. Vertical and horizontal lines denotes cutoff values for morphological classification: κ_rot = 0.6 and M_gas/M_* = 0.1, respectively.