BELINDA THE SPONGE (youtube link)
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00:01 Upon shaking (1 min vigorous agitation) the osculum contracts
00:05 Maximal inflation of the excurrent canal system 00:07 Start of the contraction of canals – this contraction begins at the peripheral choanocyte chambers and runs as a peristaltic wave pushing the water into a bolus at the base of the osculum 00:08 Maximum expansion of base of osculum. 00:08-09 Rapid contraction from base to tip of osculum. There is in fact a second contraction up the osculum. Typically the osculum shudders as all the water vents out of it. |
00:00 Upon stimulus the pinacoderm inflates (watch the surface of the tent-like membrane raise).
00:02 The contraction of the choanosome is not visible in this view, but the resulting filling of the base of the osculum is visible at 00:02. 00:03 Maximum expansion of the base of the osculum 00:03 A rapid contraction runs up the osculum – after which it expands immediately again (being filled with water from another contraction of the choanosome – which cannot be seen here). 00:04- 07 A second (less rapid) contraction of the osculum expels water from the whole sponge. 00:17– 00:27 Watch the surface of the apical pinacoderm. During this period it pulsates up and down. |
(note that the times below refer to those in the top right of the video)
10:52 A wave of contraction starts from the side opposite the osculum and moves towards the osculum. 11:06 The wave of contraction reaches the base of the osculum and dye escapes out ostia that are open around the base of the osculum (clearly seen at 11:12). 11:25-11:26 A wave of contraction runs up the osculum – quickly (dye can be seen in a stream coming out of the tip of the osculum). 11:36-11:52 The final and full contraction of the osculum (all water is vented from the canals at the base of the osculum). 12:46-12:52 After some time the sponge flinches; a spasm of contraction occurs simultaneously across the whole choanosome. |
This video shows a portion of the field of ostia on the apical pinacoderm. The ostia close in unison just prior to a first wave of contraction; they then open again, and close quickly just prior to a second contraction that can be seen as a darkening of the choanosome to the right of the ostia.
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