Image: Greenpeace, flickr

Remember sponges from the phylum Porifera in biology class? If you were a science geek like me you remember the collar cells with the flagella pulling water in and filtering it as it passes through the sponge! What a marvelous invention to naturally clean the water for many varieties of tropical fish and other organisms. And now scientists are reporting that huge sponges are coming back and getting the job done even as coral reefs die.

The decline in coral reefs along the reef tracts of the Caribbean and the Florida Keys has resulted in a competition between barrel sponges and macroalgaes (seaweed).  Although the seaweed is food for some fish it doesn’t live long. However, the barrel sponges, some the size of 50 gallon drums, filter out about 100 times their own volume every hour according to researchers in the Florida Keys. That is some serious water cleaning and that improves the environment for the underwater ecosystem..

The Aquarius Underwater Laboratory, owned by NOAA off Key Largo regularly houses scientists for 10 days at a time, 60 feet below the surface. There they can measure activity for long periods of time and observe what is happening to the reef. The barrel sponges start out about the size of thimbles and grow into large barrel- type organisms.

This is encouraging news. even though reefs are declining, for unknown or not fully understood reasons, the healthy sponge colony and the sponge’s filter-feeding seem to be improving the water quality for the fisheries around the reefs.