Species-specific behaviors drive the initiation and maintenance of snapping shrimp-goby mutualisms

Animals in obligate mutualisms perform behaviors to indicate their willingness to form partnerships and to communicate their quality to potential partners. Obligate mutualisms are difficult to study since they are formed quickly and remain in place until one partner is lost or dies. A remarkable system to ask how obligate mutualisms are initiated and maintained are those between snapping shrimp and gobies. In these mutualisms, snapping shrimp dig a burrow that provides both partners with shelter, while gobies warn the shrimp of nearby predators using tactile warning signals. To address how these mutualisms are initiated and maintained, we recorded unpartnered tiger snapping shrimp, Alpheus bellulus, and yellow watchman gobies, Cryptocentrus cinctus, interacting prior to, during, and after partnership initiation. From these recordings, we investigated the fine behavioral dynamics of initiation and the subsequent maintenance of these partnerships. While gobies lead the initiation of these partnerships through persistent contact and following of snapping shrimp, both species have an active role in initiation. To motivate gobies to initiate partnerships with them and to communicate their ability to provide shelter, snapping shrimp dig. To maintain the partnerships, we show that snapping shrimp recognize and spend significantly more time contacting their partner goby compared to a stranger goby. Altogether, our work shows that snapping shrimp-goby mutualisms require active participation by both species to be successfully initiated and maintained. Ultimately, snapping shrimp-goby mutualisms rely on species-specific roles, where the goby primarily initiates the partnership and the snapping shrimp maintains the mutualism through partner recognition behaviors.