20 million-year-old evidence discovered by scientists shows how nightmarish Bobbit worms hunted in the past.

Dreaded and Bizzare Bobbit Worm

With a staggering length of 10-feet, Bobbit worms burrow in the seafloor with their mouth sticking out as a trap. When fish, the unsuspecting prey, wanders near it, shoots with astounding speed, snaps its jaw and takes hold of its game. As its prey squirms, it drags the fish back to its lair, where it devours the fish alive.

Scientists now say that they've unearthed evidence that Bobbit worm's ancestors were laying siege to fish for over 20 million years.

Published in the journal Scientific Reports, researchers say that hundred of fossilized Bobbit worm remains in Taiwan show signs of struggle. However, scientists have not found signs of the worms themselves being invertebrates that are rarely fossilized. Scientists discover trace fossils and geological features that suggest the ancient animals' behavior in sandstone that once belonged on the seafloor.

Ludvig Lowemark, co-author and sedimentologist at national Taiwan University, says, "This is, we believe, the first time that we've actually found a trace fossil that shows how invertebrates like worms were feeding on vertebrates.

He explains that the trace fossils show how the worms burrowed in their holes, hiding in sediment, jumping out to catch their prey, and dragging them back within the sediment. A much more detailed behavior than that which was previously known.

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The fossilized burrows discovered are roughly 6.5 feet long. Based on their openings on the seafloor, Bobbit worms would burrow straight down into the much. Halfway down, worms would bend roughly by 45 degrees creating an "L." Near the entrances, researchers noticed collapse funnels or piles of sediment that built up inside the burrow. 

Scientists argue that the discovery shows signs of struggle preserved for over millions of years. It showed that as the worm dragged its victim down its hole, the fish spilled sediment that filled the void as it struggled.

Cross-section analysis shows feather-like structures within the main shaft branching off on each side. Researchers say this is due to the worm's feeding habits. Experts say that after digesting its prey, the worms reemerge out of the lairs back to the surface, reforming the collapsed tunnels.

Other sea critters burrow in the seafloor. However, scientists are confident that the recently discovered lair belongs to the ancestors of Bobbit worms. Their assurance stems from the circular shape of the 20 million-year burrows similar to modern-day Bobbit worms. Since the burrows lacked support, it would suggest that the creature inside acted as reinforcement to support the structure.

Lowemark explains, "The fact that we have a nice, round shape all the way down with no strong lining suggests that the animal was sitting in its burrow most of the time, then it rushes out. The collapse funnels represent the struggle of the prey being drawn underneath the sediment."


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