Disclosed are transgenic aquatic invertebrate for use as bioreactors to express heterologous recombinant polypeptides and its application. Also included are methods for producing transgenic Brine species and Brine cysts, and methods for expressing heterologous proteins is said cysts. The method includes introducing the foreign genes into cysts of a Brine shrimp, identification of transgenic individual and the generation of a parthenogenesis culture for transgene expression. The transgenic aquatic invertebrates described will be used as an alternative method for the low cost large-scale production of recombinant proteins, such as therapeutic proteins, polypeptide based vaccine or anti-microbial proteins, proteins for use as a food source in humans, animals and aquaculture.