Rock as food sounds a really odd thing of course for us, humans, but for other living things it's a source for nutrients. It may seem odd but some animals do eat rocks to live such as birds that use gizzard as storage to aid their digestion.
The new discovery is a type of shipworm (a group of clams that devour on woods, especially from ships) named Lithoreda abatanica (which means rock shipworm from the Abatan River). It was found in the Abatan river Bohol in the Philippines. Though the clam eats limestone, it is still unknown if how the bacteria present in it helps in breaking down the rock and release nutrients.
"We want to look at the symbionts, the bacteria that live inside these animals to see if they are providing any nutrition, and this is an area of research we are currently focusing on," said Reuben Shipway, the lead author of the study and a post-doctoral researcher at the Marine Science Center at Northeastern University in Massachusetts.
The shipworms are known to consume wood. According to Shipway, though it is hard to eat, clams are able to eat and to digest it due to their small sows of small sharp teeth on the shell and its organ known as caecum. The special organ plays a vital role for wood storage and digestion. The newfound species shook Shipway and his colleagues because of its different appetite. The species is locally known as "antingaw" and it is believed to help young mothers in lactating, according to Live Science.
Shipway added that unlike the other species of shipworm, the Lithoredo abatanica has lost its wood-boring adaptation including the caecum. It has a large shovel-like projection for digging into the rock. The species is said to be the first animal to eat rocks through burrowing. The specimens they collected were inches (10 centimeters) long but others were much larger. The animal eats, digests, and expels the rock as sand.
"When I was diving in the river, I saw burrows that were over 2 feet (60 cm) in length!" shared Shipway. "So, there may be some absolute monsters living deep in the rock."
Furthermore, it is amazing how these shipworm depends on a rock for food and leaves burrows. By doing so, it provides a habitat for other living sea creatures in the river.
