HECATE STRAIT SPONGE REEFS
View these beautiful sponges and the animals that live in and around them in two videos compiled by Sameena Sherman in our group. The videos were captured by the Phantom ROV operated by W. Carolsfeld and J. Pegg on the CGGS Vector in June 2012, during a DFO trip led by Miriam O to verify the boundaries of the proposed Marine Protected Areas.
See our two YouTube accounts for more videos:
It has long been known that sponges can contract – but all events have been considered to be local, decremental, and non-propagating, as described by Mackie in his review presented at the Paris meeting in 1979. Until recently there has been no evidence that the contractions are part of a larger ‘whole animal’ behaviour. Michael Nickel recently demonstrated that contractions known from species of Tethya do propagate across the whole animal reducing it to about 1/3 its normal size, and form part of a rhythmic behaviour to rid the animal of sediment. Some responses by Tethya can be elicited by contact by amphipods in the aquarium.
In the videos below we show that – at least in the freshwater sponge Ephydatia muelleri – contractions of the choanosome and canal system form part of a choreographed behaviour that effectively squeezes water out of the choanosome. Multiple ‘inflation-contraction’ events can be elicited by vigorous mechanical agitation (videos 1 and 2) or by adding an inedible calligraphy ink (video 3).
For details read: Coordinated behaviour in a freshwater sponge: orchestrated contractions effectively expel water from the aquiferous system (Elliott and Leys, 2007)
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.
(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.
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.
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.