The Sumida Aquarium, which is housed in the Tokyo Skytree tower, noticed that its (link in Japanese) hundreds of tiny spotted garden eels have started acting oddly, such as burrowing into the sand when aquarium workers pass by the tank.
The aquarium says that’s because the eels have become unfamiliar with humans, as it has been closed to visitors since March 1.
Garden eels are by nature highly vigilant and sensitive and do submerge themselves in the sand when triggered, but the aquarium said that the eels had learned to accept the presence of humans because there were so many visitors.
According to the California Academy of Sciences, spotted garden eels are often mistaken for plants because of their slim size and the way they burrow partially into the seafloor in order to sweep up passing zooplankton.
This article features the following image: “Spotted Garden Eel – Heteroconger hassi,” by zsispeo, licensed under CC BY-NC-SA 2.0.