Data collected on males and females of the spider species Dolomedes fimbriatus. Behavioural biology, the relationship of sex, age and body mass to voracity, boldness and propensity to attack a simulated attacker throughout ontogeny. ID = individual code Gender = 0 - female; 1 - male Stage = 1 - juvenile; 2 - sub-adult; 3 - adult Repeat = the sequence number of the experiment repetition Boldess = Score for boldness experiments (0 - bold; 5 - shy) Voracity = Score for voracity experiment (0 - did not take a fly; 1 - took a fly) Attack = Score for propensity to attack simulated prefator (0 - did not attack; 1- attacked) Mass = Specimens body mass at the time of experiment in grams Age = Specimens age at the time of experiment in days before (negative) and after (positive) final molt Difference in masa = The difference in body mass between consecutive experiments for a specimen Difference in age = The difference in age between consecutive experiments for a specimen Difference Boldness = The difference in boldness scores between consecutive experiments for a specimen Absolute Difference Boldness = The absolute difference in boldness scores between consecutive experiments for a specimen Difference Voracity = The difference in voracity scores between consecutive experiments for a specimen Absolute Difference Voracity = The absolute difference in voracity scores between consecutive experiments for a specimen Difference Attack = The difference in attack scores between consecutive experiments for a specimen Absolute Difference Attack = The absolute difference in attack scores between consecutive experiments for a specimen