The complexities of communication between the shrimp and the goby were first revealed by Lynn Moehring in 1972 when she produced her Master's Thesis at the University of Hawaii. These findings were later published under her new last name, Preston, in 1979. The symbionts she used are shown artistically in the image to the right. The goby was Psilogobius mainlandi and the shrimp, Alpheus rapax and A. rapicida. They are the same species I'm studying as part of a Predation study on Shrimp-Gobies.
She found that there is a complex warning communication between the two. The goby is essentially the 'guardian of the hole' as the shrimp has very limited visual abilities. Because of this, the shrimp, while outside the burrow, holds one antennae on the goby. If the goby sees a potential threat, it will give a slight tail flick. This vibration is picked up by the shrimp who consequently darts into the hole. If the danger approaches further, the goby will shoot into the hole through a quick C-bend of the body and enter the hole.