Starfish: Carbon storage heroes

According to a new study by British researchers, starfish and their fellow echinoderms (sea urchins, sea lilies, etc.) act as a significant sink for CO2. 

The ocean bottom-dwellers store about 2 percent of annual human CO2 emissions.

Researchers knew echinoderms store large amounts of calcium carbonate, some have bodies made up of 80 percent of the stuff, but they were still shocked by the results.  It turns out, the small animals capture about 0.1 gigatonnes of carbon per year, compared to the 5.5 gigatonnes of carbon human activity pumps into the air annually.

The team came up with the figure by gathering carbon measurements of different echinoderms from various sample sites at latitudes around the world.  They combined their measurements with population data and mortality data for the different classes to figure out how much carbon the animals stored and how quickly that carbon was buried after death.

They think the number could actually be greater since they had to form estimates for areas like the Equatorial Pacific which aren't well studied and likely have large populations.  The scientists worry what increased acidification of the oceans will mean for these carbon suckers and how it will affect the global carbon cycle if they're greatly impacted.