November 11, 2008
High Tech Sea Sponges
Researchers found that fiber optic-like cables allow sea sponges to beam light deep inside their bodies, a discovery that has delighted researchers.
German researchers published the findings in the Journal of Experimental Marine Biology and Ecology.
Sponges are among the oldest and simplest of Earth's animals.
Researchers say sponges appear to be the only animals capable of transmitting light around their bodies in this way.
They believe the finding reveals why some sponges are able to grow so big, and also clear up why smaller organisms are able to live deep within the bodies of large sponges.
Sponges lack muscles, nerves and internal organs and are essentially a diverse set of cells supported by a hard exoskeleton.
Franz Brummer, of the University of Stuttgart, and colleagues have proved that living sponges use internal glass rods called spicules as light conductors.
They say light reaching the surface of the sponge is reflected off the insides of each spicule in much the same way light bounces along the inside of a fiber optic cable used to transmit electronic data.
Brummer's team studied living sponges of the species Tethya aurantium; found in shallow waters off the coast of Croatia, and then transferred them to tanks of seawater.
They implanted light sensitive paper deep inside each sponge, and then exposed the surface of the sponge to light.
When they later checked the paper, researchers found it was covered in spots, which corresponded exactly with where light would exit each spicule.
"Sponges are fascinating animals and there're lots about them we are waiting to discover," says Brummer.
Brummer said beaming light deep inside their bodies may explain why some sponges grow to such large sizes, and develop rounded shapes.
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