Visitors at the Yokohama Yakkeijima Sea Paradise aquarium in Japan got more than what they bargained for on Monday. In the mesmerising blue waters of the tank, a stingray devoured its tank-mate, a squid, who struggled to save itself by grasping the glass wall to avoid being eaten up.

As the stingray got on with its squid feast, black ink – the dark pigment released as an escape mechanism – spread through the water. The video (above) also captured the gasps of the visitors as they watched the dramatic scene unfold. On Twitter, people questioned how the incident occurred, considering predators and their prey are kept separately in aquariums. They’re also given food at regular intervals to avoid such attacks.

In January 2016, a similar incident occurred at the COEX Aquarium in South Korea, where a tiger shark preyed on a banded hound shark.