An experiment was conducted to compare the effects of the introduced bryozoan, Bugula neritina, and the native bryozoan, Bugula dentata, on sessile invertebrate assemblages. Individuals of both species were collected from Workshops Jetty and Altona Pier prior to the experiment and transported back to the laboratory. Two colonies of either B. neritina or B. dentata were attached to each plate using sponges that expanded when wet. The plates were then transported to Workshops Jetty and attached to plates and left for 12 days. At the conclusion of the experiment plates were collected and abundances of species on the plates were counted and identified.