Indications of mutual functional benefits within a polychaete-sponge association in the northern Red Sea

Many polychaetes are commensals or parasitic symbionts of metazoan hosts that provide them with shelter and food. The genus Polydorella currently contains six species of polydorid polychaetes, of these five are described as inconspicuous epibionts (sized <2 mm) of Indo-Pacific sponges. Potential functional benefits generated by polydorid-sponge associations are still unresolved. Polydorid polychaetes may feed on detrital material accumulating on the sponge surface, but related evidence is lacking, as is knowledge on more basic properties, such as their feeding modes. Here, we report on a polydorid-sponge association observed in the Red Sea and provide new insights into potential functional benefits