Time-lapse video shows army of sea urchins marching in southern Taiwan

Amazing time-lapse video shows hordes of heart sea urchins migrating in Kenting

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Army of sea urchins. (Screenshot of Terence Chen's YouTube video)

TAIPEI (Taiwan News) -- An amazing time-lapse video showing a massive migration of maretia heart sea urchins in southern Taiwan's vacation destination Kenting has gone viral, reported ETtoday.

In the video uploaded to YouTube on July 3, diving enthusiast Terence Chen, uses time-lapse footage of a huge gathering of the normally slow-moving sea urchins to show that they are in fact marching in unison in the same direction. In his description for the video, Chen wrote that there were more even more sea urchins than last year, though their bodies were slightly smaller in size, and that many horned helmet sea snails could also be seen cruising along. 

Though many netizens attributed the mass exodus to recent typhoon activity, Museum of National Science scholar Lee Kun-hsuan believes that it is natural migration pattern, similar to what has been observed along an artificial reef off of southwestern Taiwan, as well as the Philippines and Bali in Indonesia. 

Lee said that the massive gathering of sea urchins is larger in scale than previously observed and appears to be different than the mating behavior or of other species of sea urchin. Though he is not sure what is causing the behavior, Lee does not believe it is related to the recent typhoon. 


Sea of sea urchins on the march. (Screenshot from Terence Chen YouTube video)

Because Taiwanese people are fond of eating sea urchins, some are worried that this large concentration will make them vulnerable to fishermen. Lee said that maretia heart sea urchins have a very thin, small shell with little in the way of edible meat inside. However, Lee said what would be interesting to research would be what such a large group of sea urchins is feeding on. 

Lee said the maretia heart sea urchin can usually be found buried under a thin layer of coral sand. They do not have teeth, instead they have a membrane through which they ingest grains of sand and organic detritus from the ocean floor. 


Up close view of maretia heart sea urchins. (Screenshot from Terence Chen YouTube video)

Over the past two years, they have been appearing en masse around June or July, Lee did not exclude the possibility that it has something to do with the rainy season. Lee calls on the diving community to continue to observe the behavior of this sea urchin army. 


Diver's glove gives perspective of how small the urchins really are. (Screenshot from Terence Chen YouTube video)