Ascidians, commonly called sea squirts, are one of the most evolved invertebrates. At first, they were thought to be very simple organisms but their larvae possess a notochord that clearly relates these animals to the Chordata Phylum (which includes the Vertebrates) (Kraus, 1978). The ascidian species Ascidia glabra, on which I focused, belongs to the largest class of Tunicata, the Ascidiacea Class. A. glabra are sedentary solitary sea squirts inhabiting inter-tidal zones off the East Australian Coast (Kott, 2005). Due to their relatively limited global distribution, there is only little information on A. glabra life cycle and behaviour, including their embryonic development and settlement preferences. These aspects of A. glabra life cycle were thus studied during the 2012 Heron Island field trip to try to fill the current gaps in knowledge.