THE flip side of evolution is extinction. The fossil record is replete with groups, once mighty, that are no more. But sometimes the Darwinian reaper misses a species or two within such a group and these, the last of their kind, cling on to existence to remind the world of the way it once was.
The coelacanth, a fish from the Indian Ocean; the tuatara, a reptile from New Zealand; the pearly nautilus, a tentacled mollusc of the tropical seas—all are “living fossils” of this sort. And so is Trichoplax, a flat, sheet-like creature about half a millimetre across that is the only known member of a phylum called the Placozoa. This species seems little changed from the Ediacaran period, before the Cambrian explosion of animal life.
The Ediacarans are a mystery, not least because none of those known from fossils has any sign of a gut, or any other obvious way of feeding itself. But a study of Trichoplax, just published in PLOS One, by Carolyn Smith of the National Institute of Neurological Diseases and Stroke, in Bethesda, Maryland, and her colleagues, may explain how they...
from The Economist: Science and technology http://ift.tt/1PNyvBF
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