Paralarval survival of Octopus vulgaris can be limited by temperature via short, abrupt changes (“thermal shocks”) above the natural, geographical temperature range. Thus, temperature stress can affect the growth of paralarvae. Beaks are a tool for stress, registering as darker increments (“stress marks”) during cultivation. Due to minimal knowledge of temperature stress on O. vulgaris paralarval beaks, it must be researched for improved industrialised culture. To evaluate the effect of temperature stress on paralarvae, a group was subjected to induced thermal shocks (16+3°C) for 2 hours (laboratory located ECIMAT, Vigo, Spain). Additional temperature experiments (constant temperatures - 14, 16, 18, 21°C and increasing temperature - 16-21°C) were run to determine the general effect of temperature on paralarvae. Differences in dry weight, morphometrics, stress marks and mean increment width and age (via gelatine mounting microincrement analysis of the rostral sagittal surface), were assessed between groups in the rostral sagittal surface for the thermal shock experiment. Age and mean increment width (measured on the lateral wall surface) were determined for additional temperature experiments. Dry weight and morphometrics in thermally shocked paralarvae were not significantly different compared to the control group (and for morphometrics in additional temperature experiments). Stress marks were found in 2 of 3 thermally shocked paralarvae and corresponded to the thermal shock day, however, were not statistically different to the control group. 1 of 3 paralarvae was negative for stress marks, hinting adaptability to temperature stress. Marks were observed on alternative days, possibly being “post-stress marks” or confounding stress. Increment width was not significantly different on the thermal shock day and between groups (or with increasing temperature). Positively, gelatine mounting could be a novel technique for increment visualisation. Further research is needed to validate all outcomes of this study (removing confounding stressors and increasing the sample size analysed).