Surface of Freshwater Sponge Gemmules
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Surface of Freshwater Sponge Gemmules

July 19, 2010
Surface of freshwater sponge gemmules. Gemmules are encysted spheres of thousands of sponge cells, and have a protective layer around their outside surface.

This picture was taken during research by Dr. Albert Harris and Dr. Calhoun Bond, both of Greensboro College in North Carolina. Bond was a graduate student of Harris' at the time, and was working on his Ph.D. thesis work. Their research led to the discovery that small sponges crawl (instead of being sessile, as has always been published).

Sponges can slowly move along (1 to 4 millimeters a day) by the amoeboid crawling of the marginal cells. The forces generated at the crawling margin not only move the sponge, but these forces also produce continuous rearrangement of the sponge's internal anatomy, including its skeleton of glassy spicules (thin glassy shards). This form of locomotion may be unique to sponges. Harris and Bond also discovered that the geometrical pattern of flow and propulsion of water through the interior of sponges is much different than previously thought.

Videos of sponge movement can be viewed on Bond's Web site Here. Other videos of sponge cells can be viewed under "Research" on Harris' Web site, Here. (Date of Image: 1987)

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