Jelly: our most distant relative

 Casey Dunn

Jelly: our most distant relative

Sometimes sailors on Rhode Island Sound or Naragansett Bay can see blue bioluminescent flashes in the water. When they do, they are looking at glimmerings from the most distant past of the animal kingdom. The flashes come from the comb jelly Mnemiopsis leidyi, which plays a starring role in this week’s issue of the journal Science. A National Institutes of Health-led team of researchers including Brown’s Casey Dunn, from ecology and evolutionary biology, reports that the comb jelly and its fellow Ctenophores may be a “sister group” on the evolution family tree to all other animals including people. Based on sequencing M. leidyi’s genome and then a careful statistical analysis of that data, the scientists report that long, long ago the Ctenophores split from the branch that would ultimately lead to all other animals and have continued to evolve as their own lineage to this day. In their analysis the scientists found that these jellies use very different genes to build and operate their muscles and nerves, which may indicate that they independently evolved some of these structures. The paper concludes: “This evolutionary framework, along with the comprehensive genomic resources made available through this study, will undoubtedly yield a myriad of new discoveries about our most distant animal relatives, many of which will shed new light not only on the biology of these extant organisms but also on the evolutionary history of all animal species, including our own.”