Ancient 'Shrimp Cousin' Filtered Food like Modern Whales, Researchers Say

A new study on a weird shrimp-like creature called Tamisiocaris borealis shows the species diversified from its hunter-cousins and started combing the waters to feed on tiny creatures. The research also sheds light on the explosion of life during the Cambrian period.

The feeding habits of Tamisiocaris borealis were similar to that of modern baleen whales and whale sharks. These gentle giants are huge, slow moving creatures that feed on small animals like krill.

T borealis was 70-cm-long  and belonged to a group of animals called anomalocarids, which are an ancient relative of arthropods (includes insects, shrimps and spiders). Anomalocarids are an iconic group of large predators during Cambrian period- a time in the history of life known for the sudden arrival of a large number of organisms.

The present study by researchers at University of Bristol and colleagues shows how a member of apex predators started using a net-like appendage in its mouth to eat 0.5 milimeter-sized crustaceans. T borealis lived 520 million years ago during the Early Cambrian period.

Their study was based on fossil remains of T borealis, which were found in 2009 at the northern-most tip of Greenland, Reuters reported.

 "These primitive arthropods were, ecologically speaking, 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," Dr Jakob Vinther, a lecturer in macroevolution at the University of Bristol and lead author of the study, according to a news release.

For the study, researchers created a 3D computer animation of the feeding appendage to understand how this body part moved.

Sponges are popular as filter feeders. These creatures just sit on the ocean floor and sieve the water to obtain food. According to Vinther, the filter feeding system in swimming creatures has evolved several times, especially when there was plenty of food to eat. However, T. borealis was the oldest creature to choose eating small crustaceans over large prey.

The Cambrian Period more explosive than earlier considered

The present study on Tamisiocaris borealis shows that the Cambrian period might have seen a bigger explosion of life than previously assumed. Researchers found that several species of anomalocaridids evolved and developed, meaning that there was an abundant supply of food available.

"The fact that large, free-swimming suspension feeders roamed the oceans tells us a lot about the ecosystem," Dr Vinther said in a news release. "Feeding on the smallest particles by filtering them out of the water while actively swimming around requires a lot of energy - and therefore lots of food."

The study also challenges the idea that anomalocarids were a weird, failed experiment, according to Longrich at the University of Bath. Not only did anomalocarids remain as an apex predator, but also fed on tiny plankton. Their evolution was a remarkable feat.

The study paper," A suspension feeding anomalocarid from the early Cambrian," is published in the journal Nature.