The modifications of photoluminescence properties of silica frustules of different marine diatoms induced by adsorption of nitrogen dioxide, methane, and carbon monoxide are reported. Different species of diatoms were found to exhibit different relative responses and different gas concentration ranges of sensitivity, depending on the morphology and porosity of their frustules. The photoluminescence quenching shows surface signature, exhibiting a coverage-limited kinetics according to a Langmuir mechanism. Due to the large variety of dimensions, porosities, and surface morphologies available in nature, these materials appear to be promising to improve the selectivity of gas sensing based on photoluminescence optochemical transduction.