Dancing in the dark

Three views of one animal look like a magical dancing sprite in the night sea. A relative of the Man-o’-War, the predatory siphonophore Rhizophysa, is four inches high when contracted (middle) but its stinging tentacles stretch to a couple of feet when fishing. A scuba diver captured this one in the mid-Atlantic, and part of its DNA was analyzed and recorded for the Census of Marine Zooplankton project. (Photo by Larry Madin, Woods Hole Oceanographic Institution)