Using a careful analysis of petrified seabed layers dating back some 20 million years, scientists reconstructed the lair of a giant underwater worm that would probably be hidden in sediment before jumping up to lure its prey.
The newly identified being is probably an ancestor of the Eunice aphroditois or the bobbit worm that exists today, say the researchers – these scary and seemingly modern creatures can grow up to 3 meters long, grabbing and catching their food with powerful jaws and sharp mouth parts.
While the history of worms like these may have stretched back hundreds of millions of years – perhaps as far as the early Paleozoic – this means that their soft body parts have a largely incomplete fossil record for them, making this new find significant.
The team behind the new study recovered and processed 319 samples to reconstruct a trace fossil (the trace of an animal instead of the animal itself), an L-shaped hollow with a diameter of 2-3 centimeters (0 , 8-1.2 inches) to 2 feet (about 6 and a half feet) long.
The spore fossil, also known as an ichnospecia, was named Pennichnus formosae; based on an analysis of the size and shape of the cave, as well as the signs of disturbance left behind in the rock survey, it appears to have been the home of an old worm that also sprang up from the seabed to catch prey .
“These morphological features of Pennichnus “is consistent with the activities of an ambush predator, and therefore we assume that giant polycats, such as bobbit worms, are the most likely spores,” the researchers write in their paper.
One of those morphological features is the high concentration of iron on top of the hollow. This suggests that the old worms used slime to rebuild their layer after attacks, as bacteria feeding on this slime would leave traces of iron.
Other potential residents of P. formosae, including shrimp and molluscs, are excluded: shrimp tend to make open and intricate holes, while the shape of the cavity and structure do not match the patterns left by molluscs.
The findings leave a gap in our knowledge of how these species of creatures evolved and evolved over time – and how dramatically life (and death) at the bottom of the oceans has been for millions of years.
“To sum up, we assume that ancient bobbit worms colonized the seabed about 20 million years ago, on the southeastern border of the Eurasian continent, and waited in ambush for a passing meal,” the researchers write.
“When prey came near a worm, it exploded out of its hollow and grabbed and dragged the prey into the sediment. Under the seabed, the desperate prey fled to escape, leading to further disturbance of the sediment around the opening of the hollow. “
The research was published in Scientific reports.