Preliminary study of the motility processes in the stalked heliozoan Actinocoryne contractilis

The marine stalked heliozoan Actinocoryne contractilis is capable of rapid contraction under the effect of mechanical or electrical stimulation. A brief analysis of this movement is discussed. During this contraction, microtubules of the axopods and of the stalk are destabilized. The heliozoan transforms into an amoeboid form and can creep onto the substrate. Microfilaments are visible at this stage. Polymerization of microtubular bundles initiates the regrowth of the head. Without calcium, or in the presence of inhibitors of Ca2+, contraction is considerably slowed down or totally inhibited.