Move over, sponges
Tuesday, January 27, 2009 - 13:07
in Biology & Nature
A new and comprehensive analysis confirms that the evolutionary relationships among animals are not as simple as previously thought. The traditional idea that animal evolution has followed a trajectory from simple to complex - from sponge to chordate - meets a dramatic exception in the metazoan tree of life. New work suggests that the so-called 'lower' metazoans (including Placozoa, corals, and jellyfish) evolved in parallel to 'higher' animals (all other metazoans, from flatworms to chordates). It also appears that Placozoans - large amoeba-shaped, multi-cellular animals - have passed over sponges and other organisms as an animal that most closely mirrors the root of this tree of life...