Densities of cyanobacterial cells, spicules, and particles in the coral-killing sponge <i>Terpios hoshinota</i> in Sesoko Island, Okinawa, Japan

The coral-killing sponge, Terpios hoshinota, has great potential to cover corals and threaten coral reefs. This sponge numerous endosymbiotic cyanobacterial cells, silicate spicules in the tissue, particles on tissue surface, which could have an important role growth defense of sponge. However, little is known about morphological traits these components. Here we report estimated density measurements cyanobacteria by grinding branch covered without remains. Density was be 1.2 ×107 cells cm?2. We also obtained densities for were 4.7×105 cm?2 1.3×106 cm?2, respectively. spicule length Sesoko sample shorter than those reported previous studies. Size frequency distribution measured first time, showing that selected silt-size with a mean size 22.3 µm. conclude this study provides basic information measuring components T. hoshinota useful comparing other reefs overgrown