Vinther said that evidence has also been found for water fleas, planktonic algae (which the fleas ate), small predators such as arrow worms, trilobites, comb jellies and other mid-sized species.
Taken together, he said the evidence strongly suggests that the Cambrian marine ecosystem “must have been highly productive, with a high density of production at the bottom of the food chain. This (filter feeding) strategy only evolves if there are high densities of food particles in the water, otherwise the main way to be that big is to eat things that are slightly less big with cunning stealth.”
Modern whales and whale sharks -- both filter feeders -- migrate between areas with high productivity, such as waters off the California coast and Antarctica. Baleen whales evolved when a highly-productive ecosystem first emerged around the Antarctic.
Greg Edgecombe, a researcher in the Earth Sciences Department at the National History Museum in London, told Discovery News that, until this new study, T. borealis had been known from just one specimen.
“The new specimens clear up the mystery of what this animal was,” Edgecombe said, adding that the conclusion that it was a filter feeder expands the range of feeding strategies known to have existed among the early shrimp relatives.
Derek Briggs, who is director of the Yale Peabody Museum of Natural History, told Discovery News, “Vinther and colleagues' paper provides the first clear evidence of a large anomalocaridid that fed on tiny planktonic animals rather than preying on larger forms.”
Briggs continued, “The existence of such large suspension feeders in the Cambrian was previously unknown. This discovery represents an important advance in our understanding of Cambrian ecosystems.”