Marine sponges host distinct communities of symbiotic microbes that can be acquired through both horizontal (from the environment) and vertical (from the parents) transmission. Two common species of sponges from Bocas del Toro, Panama, Neopetrosia sigmafera and Xestospongia bocatorensis, brood their developing embryos within the adult sponge. We tested the hypothesis that larval microbiomes are vertically transmitted from parents to offspring by capturing larvae released from adults of each of these two species in aquaria. We extracted metagenomic DNA from adults, larvae, and the surrounding seawater. We followed the protocols of the Earth Microbiome Project to amplify the V4 region of the 16s ribosomal RNA subunit, and sequenced the resulting amplicons on an Illumina MiSeq platform. We analyzed the resulting sequences using the mothur and DADA2 bioinformatics pipelines. We used the R package “vegan” to analyze differences in the relative abundances of bacteria between the two sponge hosts (including their adult and larval life stages) and the ambient seawater. These two sponge species host microbiomes that are significantly distinct from each other and the surrounding seawater. For N. sigmafera, a large diversity of symbiotic microbes was observed in the adults, but a subset of this diversity was hosted by larvae. For Xestospongia bocatorensis, a low diversity of microbes was hosted by both adults and larvae. Microbiome community structure was significantly different between adults and larvae of N. sigmafera, but not between adults and larvae of X. bocatorensis. These results suggest that microbiome composition might influence the differences in larval duration observed between these two species.