Researchers have used the fossils of Bobbit worm burrows to reconstruct its feeding behavior. This animal more than six feet long, which still exists today, haunted the oceans already in the Cambrian.
This creature seems to come straight out of the planet Tatooine from Star Wars. Imagine a giant worm more than 6.5 feet long, buried in the underwater sediment. Suddenly, a fish innocently passes overhead, suddenly, the worm springs from the sand and seizes its prey using powerful jaws to carry it still alive into its burrow, where it will be eaten and digested. This scenario is not taken from a science fiction novel but from a new study published in Scientific Reports, which describes the feeding behavior of the Bobbit worm, Eunice aphroditois, a species of sea worm that lived 20 million ago years.
The Bobbit worm, which has a diameter of one inch and a little more than three inches long (although specimens of ten feet have been discovered previously), still exists today. Most of the polychaete worms to which Eunice aphroditois belongs, however, do not have a predatory behavior, instead feed on detritus via deposits or filtration of seawater. They appeared at the beginning of the Cambrian, but their body being made up mainly of soft parts, fossils dating from this period are rare. It is therefore difficult to have an idea of the morphology and behavior of these ancient worms.
This is not a worm fossil that researchers at National Taiwan University in Taipei have described, but traces of its L-shaped burrow. The team based it’s dindings on the observation of 319 worm burrows more or less complete to reconstitute its habitat, which gives a good idea of its magnitude : a diameter of three inches and six and a half in length. The smooth-looking, non-collapsing burrow suggests that the worm occupied the burrow most of the time, waiting to capture prey. The researchers also observed a high concentration of iron near the mouth of the burrow, indicating that the worm probably had to rebuild it often with its mucus, the entrance to the burrow was probably continuously being destroyed by the desperate attempts, of the prey trying to escape its predator.
Other animals known to build tunnels in the sand, are shrimp or bivalves. However, “shrimp burrows generally have labyrinthine shapes and include turning spaces,” the research authors attest. Bivalve burrows, on the other hand, are not cylindrical in shape and tend to collapse. “In addition, no trace of a shell has been observed in the fossils,” note Ludvig Löwemark and his colleagues.
The Bobbit worm wasn’t the only one to haunt the oceans during the Miocene era. These were also populated by sperm whales and giant sharks such as Megalodons, which could measure up to sixty-five feet in length. Rhamphosuchus, a ferocious ten-foot-long walrus species with the jaws of a hyena, was something we would not want to run into either. In South America, also lived Megapiranha paranensis, a piranha weighing no less than 22 pounds. The rivers were also a nightmare, where giant caimans and gharials evolved like reptiles or beak crocodiles, which would make the current existing crocodiles look like dwarfs. A charming period to which we rejoice to have escaped.
