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First published online July 25, 2005
Journal of Experimental Biology 208, 2931-2938 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01738
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Flow and conduit formation in the external fluid-transport system of a suspension feeder

Michelangelo von Dassow

Department of Integrative Biology, University of California, Berkeley, 3060 VLSB #3140, CA 94720-3140, USA



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Fig. 1. (A) A colony in plan-view: a fully formed chimney (black arrow) and partially formed chimneys at the canopy edge (white arrows). (B) A diagram of a colony viewed from the side: Ch, chimney; Ca, canopy; L, lophophore; ce, canopy edge; m, mouth position at lophophore base; gray arrows, direction of flow. (C) Flow into a colony and out of a chimney (scale bar for C–F is in F). Successive frames from a black-and-white video were colorized and superimposed so that moving particles appear as rainbow streaks. The streak length is proportional to the particle speed. Lophophores appear white since they did not move. The colony was viewed from the side and illuminated with a light sheet perpendicular to the colony surface. (D) An image of the flow out of the canopy edge 2 daysbefore chimney appearance, produced as in C but with the colony in plan-view, illuminated with a light sheet at the level of the mouths. (E) A video frame showing the canopy edge of the colony in D, in plan-view, 2 days before chimney appearance. Note the columns of zooids (rectangular boxes) oriented in the direction of growth (black arrow). Red arrowheads indicate the same point on the colony in E and F (on the left edge of the chimney in F). (F) A video frame of the same colony 2 days after chimney appearance.

 


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Fig. 2. (A) A plot of particle speeds at the canopy edge in the colony shown in Fig. 1D–F. Triangles indicate center positions of zooids at the canopy edge: zooid columns that formed part of the chimney after 4 days (filled triangles) and zooid columns that did not form a chimney (open triangles). (B) Mean particle speed (± S.D.) in each zooid column of the colony in A: chimney zooid columns (filled triangles) and non-chimney zooid columns (open triangles). (C) Box-plot of median excurrent flow speed in regions that subsequently gave rise to chimneys versus regions that did not: one chimney formed in each colony (N=7 colonies). Plot shows median, 1st and 3rd quartile, 1st and 9th decile, and minimum and maximum values.

 


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Fig. 3. (A) Box-plot showing changes in excurrent flow speed after addition of either seawater or a suspension of carmine in seawater. (B) Box-plot showing growth over 5 days in colonies exposed to either seawater or carmine suspension. Numbers of colonies are in parentheses. Box-plots show median, 1st and 3rd quartile, 1st and 9th decile, and minimum and maximum values.

 


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Fig. 4. (A) An image of a colony before anesthetization. (B) The same colony after anesthetization with MgCl2. Single arrows indicate a lophophore that has turned around after anesthetization; chimney height (H) is the difference in height between the tallest part of the chimney and the shortest part of the canopy (double arrows). These images were taken in side view with the light sheet perpendicular to the colony. (C) Scatter plot of chimney height before and after anesthetization (N=6). (D) Scatter plot of the change in chimney height after replacing seawater with anesthetic (0.35 mol l–1 MgCl2).

 





© The Company of Biologists Ltd 2005