The effect of diamox and various concentrations of calcium on spicule secretion in the calcareous sponge Sycon ciliatum

Abstract

1. 1. The length, growth rate and production of monaxon spicules increased progressively with Ca 2+-concentration from the threshold (about 0.005 M) to 0.02 M. In 0.04 M Ca 2+-sea-water, however, the results differed little from those for sea-water (0.01 M Ca 2+), and the spicules tended to be aberrant. 2. 2. The addition of diamox, in concentrations ranging from 10 −7 to 10 −4 M, progressively inhibited spicule formation; the lengths, widths, growth rates and production rate were all affected. Inhibition was complete in 10 −3 M diamox. 3. 3. Returning the juvenile sponges to sea-water resulted in normal spicule formation.