Life is tough for a soft-bodied worm living in the ocean – you don’t move very fast, and your soft body means you’ve practically done half the digestion work for any predators. That was as true half a billion years ago as it is today, which is why a discovery by researchers at the University of Cambridge and Yunnan University in China is particularly enlightening: Collinsium ciliosum, or Hairy Collins’ Monster, is one of the earliest-known examples of an animal developing armor for protection.
The creature is also an example of diversity in the evolutionary history of velvet worms, which are all similar today but have poorly understood origins.
Found in the waters off southern China, Collins’ Monster would have lived on the sea floor, where it filtered food particles out of the water with it’s six feather-like front limbs. It’s nine rear legs were firm, with claws at the end. That’s not a recipe for effective locomotion on a muddy seabed, which is why researchers believe it likely clung to rocks and sea sponges, similar to some modern species.
That lack of mobility would have proved a liability for Collins’ Monster, especially since it was just a soft-bodied worm. That’s why it developed something that was, at the time, truly remarkable: It’s body was covered in up to 72 pointy spikes, effectively acting as armor. The spikes, with a cone-in-cone nesting design, are found today in the claws of some velvet worms, as well as the better-known Hallucigenia.
“Animals during the Cambrian were incredibly diverse, with lots of interesting behaviours and modes of living,” said Dr Javier Ortega-Hernández of Cambridge’s Department of Earth Sciences. “The Chinese Collins’ Monster was one of these evolutionary ‘experiments’ – one which ultimately failed as they have no living direct ancestors – but it’s amazing to see how specialised many animals were hundreds of millions of years ago. At its core, the study of the fossil record seeks answers about the evolution of life on Earth that can only be found in deep time. All the major biological events responsible for shaping the world we inhabit, such as the origin of life, the early diversification of animals, or the establishment of the modern biosphere, are intimately linked to the complex geological history of our planet.”
The results from the study are published in the journal PNAS.