At Nordsøen Oceanarium in Hirtshals, they know quite a bit about the phenomenon. We've spoken to Kim Fogt, who works daily as an outreach coordinator and educator about marine life, and who through his work has encountered thousands of the organisms that make the sea light up. The ‘culprit’ creature is the dinoflagellate. Noctiluca scintillans, a single-celled planktonic organism that lives freely in seawater and can illuminate the sea when disturbed by waves, fish, or people moving in the water, for example. When it feels disturbed, it triggers a chemical reaction that causes it to emit a brief, bluish flash of light.
It's a form of self-defence, Kim explains. The light can confuse predators like herring and mackerel that would otherwise eat phytoplankton organisms. Other organisms in the sea use bioluminescence for completely different purposes, such as attracting prey, camouflaging themselves from predators, finding a mate, or communicating with members of their own species. The light in the sea is therefore not just beautiful; it is also functional. It is nature's way of navigating, warning, and surviving, and it has fascinated humans for centuries.
In Denmark, sea sparkle isn't something you see every day. It requires special conditions. The weather needs to be warm, the water nutrient-rich, and the sea calm. Late summer is often the best time, especially August and September, and preferably on moonless evenings where the darkness makes it easier to see the light. The best spots are typically shallow bays or sheltered harbours where the water isn't too heavily disturbed by wind and currents, and these requirements were met in Nykøbing Mors on the night leading up to Sunday, 27th July.
Although it is a spectacular phenomenon, it is not something many people ask about at the North Sea Oceanarium, says Kim. “We don't actually get many questions about bioluminescence, even though it's incredibly fascinating. But when we talk about it, people immediately become curious. I think many are surprised that something so exotic can be experienced right here in North Jutland.”
Kim has not yet seen the phenomenon in the wild himself, but has seen plenty of Noctiluca He uses a microscope in connection with teaching. He finds that children and young people are both surprised and captivated when they discover how much life is hidden beneath the surface, and that it can even glow.
Nordsøen Oceanarium has previously held exhibitions focusing on bioluminescence and underwater light phenomena. In December, they will return to the theme with the exhibition “Light in the Dark,” where visitors can learn about the mysteries of the deep sea, where luminous fish, jellyfish, and other deep-sea species have made light a vital characteristic. Bioluminescence is not just something that happens on the surface. In the darkest corners of the oceans, light is what creates contact, conflict, and survival.
For Kim is the fascination not only about the visible light in the darkness but about what it represents: the diversity and complexity of marine ecosystems., “I believe many have no idea how much life actually exists in the North Sea. Bioluminescence is a reminder that there's a whole world beneath the surface – and that it's more alive than we think.” According to him, this is precisely why it is so important to convey such nature experiences. “Nature education is the keyword. The more we teach children and adults about the sea, the greater the chance that they will also look after it.”
He hopes that the phenomenon can help open the door for more curious souls and send people into nature on their own discoveries. “We hope that with good stories, we can inspire people to go out and experience it for themselves. Sometimes, a love for nature starts with something that glimmers in the dark.”
His message is clear: “The sea gives life – protect it.”
