After a recent discovery, scientists have found that ancient giant worms may have dug deep into the ocean floor to trap their prey. Their hypothesis is based on research carried out on old underground caves found in coastal Taiwan that are believed to have been formed by the giant worms.
The worms are also believed to be ancestors of modern Bobbit worms (Eunice aphroditois), which are also known for burying themselves in the sand to surprise and strike their prey.
Scientists reconstruct the burrows using trace fossils
The fossils were first discovered in 2013 at Taiwan’s Badouzi promontory by paleontologist Masakazu Nara of Kochi University in Japan. More burrows were discovered later at Yehliu Geopark, a popular tourist attraction that was once a shallow ocean ecosystem 20–22 million years ago.
The research team reconstructed the burrows from 319 fossil specimens. They discovered that the animals drilled L-shaped paths into the seafloor, leaving behind a funnel structure at the top that resembles a feather in vertical cross-sections. The burrows were about 2 meters long and 2 to 3 centimeters wide.
Their discoveries led the scientists to conclude that the tunnels were most likely dug by some kind of giant worm.
Unique hunting habit of ancient giant sea worms
The hunting habit of the giant sea worm is a unique case, as invertebrates rarely hunt vertebrates. Ludvig Löwemark, a geoscientist at National Taiwan University in Taipei, says their presence makes the local ecosystem more complex than previously thought.
“There was obviously a lot more going on at the seafloor 20 million years ago than one would imagine when seeing these sandstones,” he added.
Their hunting tactics are consistent with those of modern Bobbit worms, which conceal their 3-meter-long bodies in sand and surge forth to grab unsuspecting prey with scissors-like teeth.
Even with the similarity in their hunting habits, scientists are skeptical about the genetic link between the ancient giant worms and the Bobbit worm.