ABSTRACT
A castrating ciliate has been reported to directly consume gonadal tissues of various Asteroidea. It is known to affect mostly males and to cause gonadal regression leading to partial or total castration. The larger pyloric indices of the males from the infected population may reflect changes in their metabolism of nutrient translocation between pyloric caeca and gonads during gametogenesis. It further supports the idea of a physiological response of the starfish to the infestation, already observed at the tissue level. In a turbulent flow, such as in most benthic habitat, the success of fertilization is limited by the concentration of the spermatozoa and decreases sharply with both increased downstream distance from the male and level of turbulence.
