Hydrobiological and Microscopic Investigations of the Freshwater Sponge Ephydatia Muelleri (Demospongiae) Lieberkühn, 1856, Cultivated in a Community Fish Tank

Abstract Background: Ephydatia muelleri has become an important model organism within the realm of animal science research. This freshwater sponge is typically found in various aquatic environments, including lakes, ponds, and streams throughout India. The unanticipated and spontaneous appearance of Ephydatia muelleri in a freshwater community tank led to the present study, which sought to explore its emergence, growth (both vegetative and reproductive), and development in relation to water quality parameters. While previous research has predominantly focused on this sponge in its natural habitats such as lakes, streams, and reservoirs, this study represents a novel investigation into the growth performance and histological characteristics of Ephydatia muelleri within a freshwater community fish tank setting. Light microscopy was utilized to analyze the gemmules and the different types of spicules present in the sponge, and growth measurements (Vertical Length = VL and Horizontal Length = HL) were systematically recorded using a ruler over a three-month period from January to March 2024. Hydro-biological assessments were performed in accordance with established methodologies. Result: The results indicated that the hydrological conditions measured were ideal, promoting the growth and development of the sponge in the freshwater fish tank. Temperature emerged as a crucial factor influencing both vegetative and reproductive growth by generating asexual structures known as gemmules. During the vegetative stage, the most prevalent cells observed were scleroblasts, responsible for the secretion of mono-actinal spicules, whereas gemmules were notably abundant during the asexual reproductive phase. Conclusion: The sponge demonstrated considerable growth in the months of January and February, characterized by a rise in the production of supporting cells, scleroblasts, and spicules. In contrast, March was notable for the occurrence of gemmulation. This suggests that temperature serves as the primary ecological factor influencing both the vegetative and reproductive development of the sponge. Research of this nature is likely to encourage further investigations into other freshwater sponge species found in India.