Interestingly, the flock of shrimp “parades” to shore when the sun goes down.

At dusk, when the sun sets, it is also the time when the flock of shrimp “parades” towards the shore. They are concentrated on the rock near the river’s edge. Throughout the night, crustaceans about 2.5 cm long crawl on the rock.

The interesting scene was just filmed and shared by Watcharapong Hongjamrassilp, a graduate student at the University of California, Los Angeles (USA) on September 11.

The flock of shrimp “parade” usually appears in the rainy season from late August to early October each year in the northeast region of Thailand. That was also the time when the tourists came here very crowded. They brought lanterns to the riverbank to see the “shrimp walk” scene.

Watcharapong Hongjamrassilp knew about the shrimp parade 20 years ago. Since then, this phenomenon attracts hundreds of thousands of tourists every year. This phenomenon attracted Watcharapong, which caused him to return here to study.

Video recorded by the research team shows that the shrimp flock begins to move from dusk to dawn. They go upriver for up to 20m, and some of them are out of the water for up to 10 minutes.

“I was shocked and did not understand why they left their safe place underwater to go upriver in the dangerous dry land. Where are they going?” Watcharapong said.

The researcher then worked with wildlife center staff, surveying nine sites along a river in Thailand’s Ubon Ratchathani province. They continued to see this phenomenon at two of the sites: a rapid and a low dam.

DNA analysis results showed that these shrimp almost all belonged to the Macrobrachium dienbienphuense species of the shrimp family that lived mainly or safely in cold water. Many of these species spend their time moving upstream as their preferred habitat.

Most of the migratory shrimp the team found were small. They can come out of the water when the current is too strong. Older ones can withstand strong currents without being swept away, so they crawl less ashore than younger ones.

In fact, “walking” along the shore is very dangerous for small shrimp, even when moving around in the dark. Predators like frogs, snakes, and spiders are always on the hook.

Also, if lost, they can die before returning to the river. Sometimes Mr. Watcharapong would catch herds of stray shrimp lying on the rocks. They are sunburned, broiled until pink.

Today, the number of shrimp parades in Thailand is decreasing. Mr. Watcharapong said that this is related to tourist activities. Therefore, he hopes that his research can help in part to protect this shrimp.

Quoc Viet

According to the NY Times / Twitter