Tuesday, May 14, 2013

Living Fossils and Undying Jellyfish

Ever since Charles Darwin coined the term "living fossil," it's been bandied around very loosely.  One creature that desrves the label more than most is the coelacanth, which hasn't changed a whole lot in 300 million years. Sequencing its DNA tells us why: its genes don't evolve very fast. Those of reptiles and mammals evolve at twice this rate. Why? We're not sure.
We're not sure about this critter either - the immortal jellyfish. When it ages, it collapses into a pile of goo and starts the life cycle over again.  James Cameron never imagined anything so weird on Pandora.   

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