Friend or foe? A California two-spot octopus (Octopus bimaculoides) gives observers the eye at the Marine Biological Laboratory in Woods Hole, Mass.
Tom Kleindinst/Marine Biological Laboratory
It's a bacteria-eat-bacteria world, scientists say. Bdellovibrio bacteriovorus, shown here in false color, attacks common germs six times its size, then devours them from the inside out.
Alfred Pasieka/Science Source
A white-throated round-eared bat (Tonatia silvicola) catches — and munches — a katydid on Barro Colorado Island in Panama. Katydids are "the potato chips of the rain forest," scientists say.
Christian Ziegler/ Minden Pictures/Getty Images