Some Ancient Comb Jellyfish Had Armored Bodies and Lacked Tentacles

Posted on August 2, 2015

Ancient skeletonized comb jellies

Modern comb jellies are known for their gelatinous tissue and tentacles. They were not always like this. New fossil discoveries have found that ancient comb jellyfish lacked tentacles and had spiky armored bodies and skeletons. Six fossils of the 520-million-year-old jellyfish were found by researchers in China.

A report on the ancient comb jellies can be found here in the journal, Science Advances, in an article called, "A vanished history of skeletonization in Cambrian comb jellies." The fossils show some of the creatures had radiating flap-like structures with spokes and comb rows. They also had other spokes, spines and hard body parts.

Qiang Ou, a co-author of the study from the China University of Geosciences, told LiveScience, "I was most surprised when I realized they were skeletonized comb jellies. That they were overlooked is more or less because such fossils are very rare."

Without tentacles the ancient comb jellies would need a different way to capture prey. Some modern ctenophores also lack tentacles and are still capable of feeding. Rebecca Helm, a biologist at Brown University, explained to LiveScience that lobate ctenophores capture prey by trapping it in "an ever-contracting dome of flesh." Helm says, "Prey is forced closer and closer to the ctenophore mouth, until eventually it is consumed."

A PDF file describing the different Cambrian comb jelly fossils discovered can be found here.

Photo: Qiang Ou/Science Advances