Tardigrades Are One Giant Head

No one would argue that tardigrades got stiffed in the weirdness department. These teensy animals, also called water bears, look roly-poly under a microscope. Less than a millimeter long, they can survive extremes of heat, cold, pressure, and radiation that are deadly to most other lifeforms. Under duress, a tardigrade may curl itself into a dried-up ball called a tun, then stay in a state of suspended animation for years before returning to life. Now, researchers poring over the animal's genes have found another oddity. The tardigrade, they say, is essentially one giant head. Frank Smith, who's a postdoc in Bob Goldstein's lab at the University of North Carolina, Chapel Hill, and their colleagues studied the evolution of tardigrades by looking at their genes. Specifically, they looked at bits of DNA called "Hox genes." These are master controllers that organize an animal's body. During development, Hox genes make sure all ...