Taking the Pulse of the Ocean’s Comb Jellies

New kinds of molecular probes are revealing the true extent of ctenophores, a form of ocean life that has long eluded firm reckonings.

The enormousness of the global sea has, over ages of exploration, made the appraisals of prime inhabitants more like rough sketches than detailed portraits. Now, scientists have devised a precise way of detecting one of the ocean’s more exotic creatures. Estimates of its global abundance, they say, will likely soar. The organisms are known as ctenophores. While looking superficially like jellyfish, they have no stingers and none of the usual body pulsations and rhythms that power jellyfish. Instead, what moves them through seawater are pulsating rows of feathery cilia. The tiny hairlike bundles resemble the teeth of a comb, giving the creatures their other name: comb jellies.