More than half a billion years ago, a bizarre creature swam in the oceans near modern Greenland. The shrimp-like species, named Tamisiocaris borealis or "weird shrimp" by scientists, was over two feet long, but that alone that wasn't what made it unique. According to research published this week in the journal Nature, this animal had an unusual feeding method that set it apart from its relatives of the day.
Unlike other shrimp-like species of the Cambrian era, which snared their food with sharp claws, the newly discovered Tamisiocaris borealis had two long, comb-like appendages attached to its face. These comb-like structures would sweep the water in front of the shrimp to trap tiny plankton as small as 0.5 millimeters in size. This is similar to the filter-feeding method used by today's blue whales, which use baleen to suck tiny food particles out of the water. The researchers who described the species based on recently discovered fossils call it a gentle giant compared to other species of the day.
"Tamisiocaris would have been a sweep net feeder, collecting particles in the fine mesh formed when it curled its appendage up against its mouth," co-author Dr. Martin Stein of the University of Copenhagen said in a news release. "This is a rare instance when you can actually say something concrete about the feeding ecology of these types of ancient creatures with some confidence." You can see these feeding appendages in action in this computer simulation created by Stein:
Lead author Dr. Jakob Vinther of the University of Bristol said the "weird shrimp" were sort of like "the sharks and whales of the Cambrian era. In both sharks and whales, some species evolved into suspension feeders and became gigantic, slow-moving animals that in turn fed on the smallest animals in the water."
This feeding action may have been "gentle," but it also required Tamisiocaris to burn a lot of energy while it swam around. That meant it also needed to eat a lot. The researchers say the revelations about Tamisiocaris reveal that the group of animals called anomalocarids — previously considered to be an evolutionary failure — were in fact enjoying what another co-author called "a major evolutionary explosion," which allowed them to do "everything from acting as top predators to feeding on tiny plankton."
The researchers say this reveals new information about the ecosystem of the Cambrian period. They also hint that there may be more revelations to come. The same expeditions that discovered the "weird shrimp" also uncovered many other fossils that are still sitting in laboratories, waiting to be described. We can only hope that they will be equally weird and wonderful.
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