If this animal were named the "sausage worm", would you be reading this article right now? Probably not, but who cares, because we know that organisms become infinitely more interesting when they resemble the male genitalia.
Like our wonderful penis snakes, penis worms rightfully earned this name because of their unfortunately hilarious phallic shape. These marine worms burst onto the scene some 500 million years ago, during the Cambrian period, and there are still many species alive today. But it seems there has been a whole world of penis worms that managed to slip through scientists’ radars, until now.
After collecting and analyzing fossilized teeth of these willy-like worms from all across the world, scientists have compiled what they are nicknaming a “dentist’s handbook,” which has indicated that these animals were more diverse than originally believed. Furthermore, researchers may have discovered several species which were previously unknown to science. The findings have been published today in the journal Palaeontology.
Penis worms, or priapulids, are floppy, tubular animals that can be found sitting snugly in self-made holes on the sea floor. They might not look overtly threatening, but size isn’t everything: these worms are believed to have been rapacious predators during the Cambrian, devouring any small marine critter they could get their chops around. Rather revoltingly, they also possess an eversible mouthpart - which means it can turn inside out - called a proboscis which is lined with sharp teeth, somewhat resembling a cheese grater.
Alongside using these gnashers to devour prey, the animals used their toothy proboscis to cling onto the seabed and pull themselves along, slowly slithering across the sediment. Beautiful imagery.
Although the fossil record has indicated that priapulids were extremely common during the Cambrian period, our knowledge of the species present and their distribution during this time has been limited by the fact that they are soft-bodied animals. That means that they are much less likely than hard-bodied organisms to leave behind a fossil for scientists to find. But luckily for us, many left some of their teeth, providing scientists with a window of opportunity to find out more about their diversity.
So researchers from the University of Cambridge began scouring through specimens collected from the Burgess Shale, a rock formation in Canada renowned for being extremely rich in Cambrian fossils, with the hope of finding some of these teeth. This was no mean feat, given the fact that they are only around 1 millimeter in length and easily mistaken for spores. However, after scrutinizing the samples with a microscope, they managed to find a treasure trove of teeth belonging to the species Ottoia prolifica, which ranged from spiky cones to claw-shaped.
After compiling a handbook of all the different teeth they found, they discovered that some just didn’t seem to fit in with the rest. For example, some were lined with a different number of prongs to the rest, indicating that they likely belonged to a different species. The scientists therefore suggest that some O. prolifica samples may have been wrongly labeled, and may actually belong to a new species, which has been dubbed O. tricuspida.
But the work isn’t over yet, as the researchers believe there could be numerous other species waiting to be discovered in these rocks, which suggests that these animals were likely even more diverse than long believed.