(Photo: Frank Fox)You can close your mouth, but yo...  ...e still a gap. It's a different situation for the Hydra viridissima. The hydra 's mouth disappears at the cellular level when clo...  ...niversity of California, Irvine discovered why: a hydra mouth is not a permanent op...

Deep inside the Strategic Homecooking Is E...  ...ng Logistics Division (S.H.I.E.L.D.) is a sleeper Hydra agent who goes by the Instagram nickname elholowi...