Researchers associated with numerous institutions across the U.S. have discovered a rare species of shipworms named Lithoredo abatanica that feeds on rocks and stones instead of woods. They published a paper in the Proceedings of the Royal Society B and described their study and the discovery.
The shipworms are water-dwelling mollusks which are known due to their ability to chew the wood and digest it. They are also popular for creating holes in wooden structures present in water and now, the researchers claim to have discovered a species of these shipworms that do not feed on wood at all but eats the limestone instead.
After breaking through the rocks to get a specimen of these worms, they reported their small size of 150mm and their close resemblance to worms than other mollusks. Unlike the wood-eating shipworms, these worms have large, flat teeth that could scrape away rocks unlike, sharp invisible teeth of the wood eater ship worms which could cover the shells and lacked the sac which was used to digest these woods. In addition to this, these shipworms were also found to excrete sand. Researchers, however, cannot determine any motive behind their rock eating nature but say that it does not impart any nutritional value.
These ship worms which eat rocks have the tendency to change the course of rivers as well. These shipworms have extremely shrunken shells, two in number which is modified into drill like heads.
The regular wood eating marine ship worms store the wood that they eat in a very special digestive sac which they ingest and scrape away to make a protective burrow for itself. The rock-eating ship worms do the same except that they differ from the usual ones in the fact that they lack the sac.
The rock-eating ship worms rely on the bacteria that reside in their gills to produce nutrients and food which is sucked in by this newly existing shipworms from the hind end for nourishment. The gills found in the stone-eating shipworms are quite larger than normal, which shows that they are important for their survival. Researchers are working on how their metabolism works.