Symbiosis
Another example is the goby fish, which sometimes lives together with a shrimp. The shrimp digs and cleans up a burrow in the sand in which both the shrimp and the goby live. The shrimp is almost blind, and is vulnerable to predators when above ground. When a predator approaches, the goby touches the shrimp with its tail as a signal. When that happens both the shrimp and goby quickly retreat into the burrow.