ScienceDaily (Nov. 26, 2009) — Coral reefs support some of the most diverse ecosystems on the planet, yet they thrive in a marine desert. So how do reefs sustain their thriving populations?

Marine biologist Fleur Van Duyl from the Royal Netherlands Institute for Sea Research is fascinated by the energy budgets that support coral reefs in this impoverished environment. According to van Duyl's former student, Jasper De Goeij, Halisarca caerulea sponges grow in the deep dark cavities beneath reefs, and 90% of their diet is composed of dissolved organic carbon, which is inedible for most other reef residents. But when De Goeij measured the amount of carbon that the brightly coloured sponges consumed he found that they consume half of their own weight each day, yet they never grew.

What were the sponges doing with the carbon? Were the sponges really consuming that much carbon, or was there a problem with De Goeij's measurements? He had to find out where the carbon was going to back up his measurements and publishes his discovery that sponges have one of the fastest cell division rates ever measured, and instead of growing they discard the cells. Essentially, the sponges recycle carbon that would otherwise be lost to the reef. De Goeij publishes his discovery on November 13 2009 in The Journal of Experimental Biology.

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