Behavioral Study: Discussion

In goby bay, snapping shrimp (Alpheus rapax) and shrimp-gobies (Psiligobius mainlandi) are found together on almost every occasion (except a few small gobies seen occasionally – pers. Obs.). They are, like many other shrimp gobies considered to be obligate partners (Moehring, 1972; Karplus, 1987). The question, however, is: “Does this make them mutualistic in their association.” The answer is no. It does not mean they have to be mutualistic. Yet, many authors have noted this, even though no quantifiable studies have been conducted proving this case. This study attempted to fill this void.

The data collected suggests that there is a significant impact on the shrimp’s behavior, elicited by a removal of the goby. When a goby was removed the shrimp spent less time out of the hole, less time out of the hole on a single ‘bout’ and a greater percentage of the bouts that it did take, were digging. Each of these measurements seem to indicate that the shrimp’s activity is dampened because of the absence of the goby.

When shrimp are out of the hole they have time to scout the surrounding sand for objects to bring back into the hole. They will often release loads of sand and then seem to ‘search’ for food around the entrance. This activity though, was only done when gobies were present out of the hole. When there wasn’t a goby they never searched. Instead, they spent every amount of time digging. This activity may in fact be necessary for the maintenance of the hole while spending time outside is not.

The next step that must be taken is to determine what benefit the shrimp gets from being out of the hole and not digging. While it seems that it could be searching for food, it is not that obvious. If there is in fact a significant benefit too being out of the hole, the gobies give them that benefit, thus making the relationship mutualistic in nature. If it is found that the food is actually acquired inside the hole, and that the only reason for being outside the hole is for the gobies sake, then the shrimp may be altruistic in nature. What it comes down to is the cost and benefit each individual gets from the association. This question, however, may be more difficult to answer than determining whether not the shrimp changes its behavior when a goby is removed.

Acknowledgements

I would like to thank Dr. George Losey for his support and help setting up the camera apparatus and for giving me permission to use his wet lab for aquarium studies. I would also like to thank Dr. Tim Tricas and Dr. Jim Parrish for their comments and suggestions. Thanks also to Georgi Kinsela and Kimberly Goetz for help sampling.

References

• Harada, I. 1969. On the interspecific association of a snapping shrimp and gobioid fishes. Publ. Seto Mar. Biol. Lab. 16: 315-334.
• Karplus, I. 1981. Goby-Shrimp partner specificity. II. The behavioural mechanisms regulating partner specificity. J. Exp. Mar. Biol Ecol. 51: 21-35.
• Karplus, I. 1987. The association between gobiid fishes and burrowing alpheid shrimps. Oceanogr. Mar. Biol. Ann. Rev. 25: 507-562.
• Karplus, I., Szlep, R. and Tsurnamal, M. 1981. Goby-Shrimp partner specificity I. Distribution in the northern Red-Sea and partner specificity. J. Exp. Mar. Biol. Ecol. 51: 1-19.
• Luther, W. 1958. Symbiose von Fischen (Gobiidae) mit einem Krebs (Alpheus djiboutensis) in Roten Meer. Z. Tierpsychol. 15: 175-177.
• Magnus, D.B.E. 1967. Zur Okologie sedimentbewohnender Alpheus Garnelen (Decapoda, Natantia) des Roten Meers. Helgolaender. Wiss. Meeresunters. 15: 506-522.
• Moehring, L.J. 1972. Communication systems of a goby shrimp symbiosis. Ph.D. thesis, University of Hawaii, 373 pp.
  Polunin, N.V.C. and Lubbock, R. 1977. Prawn-associated gobies (Teleostei: Gobiidae) from the Seychelles, western Indian Ocean: Systematics and ecology. J. Zool., Lond. 183: 63-101.
• Yanagisawa, Y. 1984. Studies on the interspecific relationship between gobiid fish and snapping shrimp. 2. Life history and pair formation of snapping shrimp Alpheus bellulus. Pbul. Seto. Mar. Biol. Lab. 29: 93-116.
• Yanagisawa, Y. 1978. Studies on the interspecific relationship between gobiid fish and snapping shrimp. 1. Gobiid fishes associated with snapping shrimps in Japan. Publ. Seto mar. Biol. Lab. 24: 269-325
• Yanagisawa, Y. 1982. Social behavior and mating system of the gobiid fish Amblyeleotris japonica. Jap. J. Ichthyol. 28: 401-422.