The effects of increased external Ca and K concentrations on the waveform dynamics of bryozoan spermatozeugmata

To investigate Membranipora membranacea (Linnaeus 1767) sperm modulate their waveforms, including the production of type 111 waveforms that are important for sperm spawning and entry into, maternal individuals, unencapsulated sperm aggregates or spermatozeugmata were exposed to elevated concentrations of external Ca ++ and K’. Increasing Ca levels by 20 and 30 mM above ambient caused spermatozeugmata to increase the duration, but not the frequency of type 111 waveform events. Increasing ambient levels of Ca ++ by 40 mM or K + by 10 or 20 mM produced a waveform, type IV, that propagated from tail to head and caused the anterior ends of the spermatozeugmata go through an effective stroWrecovery stroke; motion comparable to the movement of a cilium. Type IV waveforms propelled spermatozeugmata forward through the water column and may be the waveform used by spermatozeugmata to pull themselves into intertentacular organs to enter maternal zooids.