Inside the mouth of a hydra: Hydra rips its own skin apart just to open its mouth

Hydra is a genus of tiny freshwater animals that catch and sting prey using a ring of tentacles. But before a hydra can eat, it has to rip its own skin apart just to open its mouth. Scientists now illustrate the biomechanics of this process for the first time and find that a hydra's cells stretch to split apart in a dramatic deformation.