Sponginsecreting

Sponginsecreting is the biological process by which some sponges synthesize and secrete spongin, a soft, fibrous protein that forms part of their skeleton. Spongin-based skeletons confer elasticity and resilience, helping sponges withstand water movement while maintaining their filter-feeding structures.

The secretion of spongin occurs in specialized mesohyl cells called spongocytes (also known as sponginocytes). These cells produce spongin and release it into the extracellular matrix, where it forms a network of fibers that can constitute the sponge’s main framework or be integrated with other skeletal elements. In many demosponges, spongin fibers are embedded with silica or calcium carbonate spicules to create a composite skeleton; in other species the skeleton is predominantly spongin, producing a softer, more flexible body.

Patterns of sponginsecreting vary among sponge groups and are influenced by developmental stage, habitat, and environmental conditions such as water flow and nutrient availability. The resulting material properties—elasticity, porosity, and strength—affect the sponge’s morphology, ecological niche, and how it interacts with its environment.

Human relevance arises from the fact that many commercially exploited bath sponges derive from spongin-rich species. Understanding sponginsecreting contributes to broader knowledge of sponge biology, skeletal evolution, and the diversity of extracellular matrix proteins in the animal kingdom.