This dataset was collected in two separate experiments in 2019/20 and 2020/21, looking at the behaviour of juvenile Acanthaster cf. solaris as they transition from their initial herbivorous diet feeding on crustose coralline algae (CCA) to feeding on coral. We aimed to fill key knowledge gaps by identifying the age and size COTS would transition, as well as identifying 50% and 100% probabilities of transition for the cohorts. We also looked at the effect available coral species have on the probability of COTS transitioning, comparing preferred foods Acropora millepora and A. tenuis to Stylophora pistillata. COTS were isolated in flow-through tanks in the Australian Institute of Marine Science’s National Sea Simulator, and provided with CCA and the relevant coral species. In Experiment 1, one COTS was added per tank with CCA and A. tenuis, and was monitored weekly for a transition to a coral diet. In Experiment 2, 10 COTS were added per tank, with CCA and either A. millepora, A. tenuis or S. pistillata, with four replicate tanks per coral treatment. When COTS were observed feeding on corals, they were removed, photographed and their size and age recorded. Experiment 1 was run until all 24 COTS used in the experiment had transitioned, whilst Experiment 2 was run until >50% of the cohort in the A. tenuis treatment (the COTS preferred food) had transitioned.

Parameters common to both:

Age – Age of Acanthaster cf. solaris juveniles in days post settlement

Arms – Number of arms on individual Acanthaster cf. solaris

Diameter – Average diameter of Acanthaster cf. solaris individuals measured in millimetres from the tips of the arms

Coral – The coral species the Acanthaster cf. solaris was found feeding on

Exp 1

Tank Row – the row the COTS tank was in

Tank Column – the column the COTS tank was in

Exp 2

Tank Rep – The replicate number of the tank for each coral species (n = 4 for each species)

Tank No – The individual tank ID number

Exp 2 – binomial feeding

CCA/Coral – 1 indicates this was the diet of the COTS specimen at the end of the experiment (day 175), 0 indicates it was not