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| Macrobrachium dienbienphuense Dang & Nguyen, 1972 Parading shrimps synchronously walking on land at night at the Lamduan Rapids, Ubon Ratchathani, Thailand. in Hongjamrassilp, Maiphrom et Blumstein, 2020. DOI: 10.1111/jzo.12841 Photos: Watcharapong Hongjamrassilp |
Abstract
An understanding of the mechanisms and functions of animal migratory behaviour may provide insights into its evolution. Furthermore, knowledge about migration may be important for conservation of rare species and may help to manage species in a rapidly changing world. Upstream migration is common in riverine animals, but little is known about proximate cues and functions of the upstream migration in aquatic macroinvertebrates. In Ubon Ratchathani, Thailand, locals have observed a synchronous mass migration of freshwater shrimps on land. This so‐called ‘parading behaviour' occurs annually during the rainy season and has become a large ecotourism event. Yet, we know little about the natural history, proximate causation and function of this extraordinary behaviour. Here we describe the natural history of parading behaviour and report the results from a series of experiments and observations to address its mechanisms and functions. Parading behaviour is not associated with breeding and spawning; rather, shrimps leave the water to escape strong currents. Conditions promoting shrimps to leave the water include low light, high water velocity and low air temperature. In addition, there is variation explained the specific location. River topology that creates hydrological variability and turbulence plays a role in triggering the shrimps to move out of water. Furthermore, turbidity and water chemistry were associated with shrimp activity. Finally, our results support that parading behaviour in freshwater shrimps is a mass movement upstream due to hydrological displacement. This study highlights the mechanisms that stimulate parading behaviour; a common activity in Macrobrachium and other decapod crustaceans.
Keywords: collective movement, freshwater prawn, Macrobrachium dienbienphuense, migration, Southeast Asia
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| Parading shrimps synchronously walking on land at night at the Lamduan Rapids, Ubon Ratchathani, Thailand. Photo: Watcharapong Hongjamrassilp. |
W. Hongjamrassilp, W. Maiphrom and D. T. Blumstein. 2020. Why do Shrimps leave the Water? Mechanisms and Functions of Parading Behaviour in Freshwater Shrimps. Journal of Zoology. DOI: 10.1111/jzo.12841
These Shrimp Leave the Safety of Water and Walk on Land. But Why?
A biologist decided to investigate a shrimp parade that attracts thousands of tourists in a province of Thailand.
