The pistol shrimp has terrible eyesight. But some species of the shrimp get help -- not spectacles, but a companion fish: a goby. It keeps an eye out for predators. In turn, the shrimp maintains a burrow that’s used by both of them.
The pistol shrimp gets its name from one of its claws, which is larger than the other. It snaps the claw shut quickly, generating bubbles. When the bubbles collapse, they produce a loud sound -- like a gunshot. That can stun prey, and allow the shrimp to communicate with other shrimp around it.
After just an hour or so without oxygen, your heart develops permanent damage. Shortly afterward, it stops beating entirely. Not so with the resilient hagfish, a slimy eel-like creature that feeds on dead marine animals that fall to the ocean floor. In fact, the hagfish’s heart continues beating and supporting normal activity for up 36 hours without any oxygen at all. What scientists haven’t understood is how or why.
