The tactile alarm system between the symbiotic goby Cryptocentrus steinitzi and its burrowing shrimp partner Alpheus purpurilenticularis was investigated by underwater observations in the northern Red Sea. Warning signals by the goby which elicit the retreat of the shrimp into its burrow consist mainly of rapid tail flicks transmitted to the shrimp through its long antenna. No warning signals are given without that contact. The daily rhythm of the antennal contacts was described. Warning signals are emitted by the goby in a selective manner only in response to the approach of certain species of fish to the burrow entrance. The response of the shrimp to warning signals was described. The goby-shrimp communication system was used to study predator recognition in a series of controlled experiments. The sequence of the acts of the goby and shrimp was analyzed.