Picture a beach at night. A wave rolls in and, as it breaks, it flashes a bright, glowing blue. It looks like something from a film, but it is real. Glowing waves have been seen on beaches in Chennai, along the Karnataka coast, in Visakhapatnam, on Havelock Island in the Andamans and on Bangaram Island in Lakshadweep.
The tiny light-makers
The glow comes from tiny living things floating in the sea. One of them is called Noctiluca scintillans, nicknamed “sea sparkle”. Each one is a single cell, only about as big as a grain of sand. But when huge numbers gather together in what scientists call a bloom, they can light up the water.
How do they glow?
Making light inside a living body is called bioluminescence. Inside these tiny organisms, a substance called luciferin reacts with oxygen, helped by an enzyme (a helper chemical) called luciferase. This reaction gives off cold light, which means it makes almost no heat. The organisms flash when they are disturbed, so the glow shows up most where waves crash.
Beautiful, but a warning
Scientists enjoy the show, but they also watch it carefully.
- Sea sparkle is often found in water that has little oxygen.
- It is a predator that eats other tiny sea life, which can upset the food chain (who eats whom in the sea).
- It can give off ammonia, which in large amounts can kill many fish.
- Some experts think more blooms may be a sign of unhealthy waters and of climate change.
Blooms are seen more often in warm weather. So a glowing beach is both a wonder and a message from the sea that scientists want to understand.
Watching safely
If you are lucky enough to see glowing waves, enjoy them from the shore with an adult. Never go into the sea at night.
Wonder about: If glowing waves can be a warning sign, what changes in the sea do you think scientists should check first?