Microscopic placozoans carry the genetic blueprint for complex bodies they no longer possess
The simple, disc-shaped Placozoa possess the complex Hox genes required to build symmetrical bodies and organs, despite having no mouth, gut, or nervous system of their own.
Trichoplax adhaerens, a member of the Placozoa phylum, is a millimeter-sized creature that lacks organs, symmetry, and a digestive tract, yet it carries the genetic instructions for a far more complex body. These animals possess Hox-like genes, the master controllers usually responsible for patterning heads, tails, and limbs in advanced organisms. Their genetic makeup suggests they are not primitive survivors, but rather the descendants of more complex ancestors that underwent extreme physical simplification approximately 600 million years ago.
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