Living systems have evolved highly precise ways to sense and respond to microbial cues, yet the rules governing these interactions remain unclear. Understanding these mechanisms is essential not only for biology, but also for advancing biotechnology platforms that harness microbial products to control cell behavior. This project addresses a fundamental question in biology: how do animals interpret microbial cues to regulate development. By revealing how conserved biological pathways link bacterial sensing to developmental decisions, this work will advance understanding of host–microbe interactions. The results have the potential to inform strategies for marine ecosystem restoration, including enhancing larval recruitment in degraded habitats, while also establishing foundational principles for biotechnology applications that harness microbial cues to control biological processes. Discoveries from this research are thus expected to enable emerging biotechnology platforms, illustrating how fundamental insights can translate into new environmental and biomedical applications. The project will also support workforce development through hands-on research experiences for undergraduate and graduate students, including a course-based program that engages early-career students in discovery-driven science. In addition, this project advances NSF’s priorities in Biotechnology. This project uses the marine tubeworm Hydroides elegans as a model system to define how animals detect bacter