Through careful analysis of fossilized seafloor layers some 20 million years old, scientists have reconstructed the burrow of a giant underwater worm that would most likely have been hidden in sediment before leaping up to ambush its prey.
The newly identified creature is likely an ancestor of the Eunice aphroditois or bobbit worm that exists today, the researchers say – these scary-looking modern creatures can grow up to 10 feet (3 meters) long, grabbing and catching their food with powerful jaws and sharp mouthparts.
While the history of worms like this is thought to go back hundreds of millions of years – perhaps as far as the early Paleozoic Era – their soft body parts mean there is a largely incomplete fossil record for them, making this new find significant.
The team behind the new study recovered and processed 319 specimens to reconstruct a trace fossil (the trace of an animal, rather than the animal itself), an L-shaped cave about 2-3 centimeters in diameter (0, 8-1.2 inches) and up to 2 meters (about 6 and a half feet) long.
The trace fossil, which is also known as an ichnospecies, has been named Pennichnus beautiful!; Based on an analysis of the size and shape of the cave, as well as the signs of the disturbance left in the bedrock, it appears that it was home to an ancient worm that also jumped out of the sea floor to catch prey .
“These morphological features of Pennichnus are consistent with the activities of an ambush predator, which is why we hypothesize that giant polychaetes, such as bobbit worms, are the most likely spore makers, ” the researchers write in their paper.
One of those morphological features is the high concentration of iron up to the top of the cave. This suggests that the ancient worms used slime to rebuild their burrows after an attack, because bacteria feeding on this slime would have left traces of iron behind.
Other potential residents of P. formosaincluding shrimp and mollusks were excluded: shrimp tend to make more open and complex burrows, while the shape and structure of the burrow does not match the patterns left by mollusks.
The findings fill a gap in our understanding of how these types of creatures evolved and evolved over time – and how dramatic life (and death) at the bottom of the oceans has been for millions of years.
In summary, we hypothesize that about 20 million years ago, on the southeastern border of the Eurasian continent, ancient Bobbit worms colonized the sea floor in ambush waiting for a passing meal, the researchers write.
When the prey got close to a worm, it exploded out of its burrow, grabbed and dragged the prey down into the sediment. Below the sea floor, the prey desperate to escape, further disrupting the sediment around the hole. “
The research is published in Scientific reports.