Rethinking Plasticity in Sponges

What lies behind the extraordinary phenotypic plasticity of sponges? We used this question to conduct a systematic review of how "phenotypic plasticity" is approached in the literature regarding the phylum Porifera. First, we gathered information on what the literature says about plasticity in sponges. Next, we analyzed its usage contexts, distinguishing between plasticity as a general feature versus a specific process linked to environmental triggers or genetic variation. Thus, we critique the overuse of synonymous terms that fail to capture the concept's complexity and advocate for greater precision to advance research. Finally, we advocate for precise and consistent terminology as an essential requirement for advancing research on sponge phenotypic plasticity. Phenotypic plasticity in sponges is a multifaceted phenomenon. We focused on the rationale behind the term's use and its underlying biological assumptions, proposing a categorization into three levels: (1) intraindividual/cellular plasticity, regarding modifications in a single organism's structures; (2) individual plasticity, involving whole-organism adaptation; and (3) population-level plasticity, where variability occurs among individuals of the same species. This framework distinguishes between changes within a single organism and broader variation patterns, highlighting scale-specific biological constraints. Recognizing sponges as highly plastic organisms was only the beginning. We advanced our comprehension by addressing key evolutionary questions and knowledge gaps that remain essential to guide future research on the molecular, ecological, and evolutionary implications of plasticity in this phylum.