Shrimps

A mutualistic symbiosis exists between the alga Sargassum spp. and two shrimp species, L. tenuicornis and L. fucorum. But little is known about how the shrimp locate their host alga. Both visual and chemical cues are potentially available. Visual cues would be presumably restricted at night but chemical cues are potentially available continuously. Additionally, a previous study has looked at both cue variables with results that are mixed. This current research elaborates on the previous study in an attempt to fully understand Sargassum shrimp chemoreception. A y-maze and four-chambered apparatus were used to test if the shrimp were able to detect Sargassum cues, conspecific cues, and Dimethylsulfoniopropionate (DMSP) cues. Neither shrimp species showed a strong directional response to any of the chemical cues, but the Sargassum and DMSP cues did cause more shrimp to exhibit searching behavior. Additionally, several differences in response between male and female shrimp were found for each cue. A weaker dilution of DMSP was tested in an attempt to determine sensitivity of L. fucorum shrimp to the chemical cue. This weaker dilution also caused L. fucorum to exhibit searching behavior, but the sensitivity to the cue was not found and further research is needed to fully answer this question. These results show the shrimp are able to detect chemical cues in their environment and help determine more accurately the role of chemoreception in initiating and maintaining this shrimp/algal association.

Periclimenes yucatanicus, P. pedersoni, and Thor sp. were nonrandomly distributed among three anemone species at different sites off southern Florida. Host selection tests showed that P. yucatanicus had a strong preference for one anemone, which could explain its field abundance with this same species. Host location tests showed that both Periclimenes species used chemical cues to detect their anemones--visual information seemed unimportant. Laboratory predation trials showed that shrimp survived significantly longer with an anemone than without in the presence of predatory fishes. The acclimation behavior of Periclimenes was described to analyze the protection mechanism. Legs and antennae were in frequent contact with the anemone, but the other body regions rarely contacted the tentacles. Additionally, antennae were used frequently to direct tentacles away from these other body regions. Coating of high contact areas with anemone mucus and avoidance of tentacles with other areas may be the method of protection.