If you’ve ever walked along the beach on a windy day, you’ve probably felt foam squishing between your toes along with the sand. But how does this frothy ocean top layer form? The recipe involves proteins, fats, air, water, and agitation from wind and waves. Explore how these ingredients come together in the graphic below!
Want to make your own "sea foam"? Check out our hands-on activity relating this formation process to the milk foam in your favorite winter latte!
Sea foam is made up of micelles, which are small spheres made of surfactants surrounding air. These surfactants are proteins and fats that came from decaying marine life, like plankton. (Image credit: NOAA Office of Education)
Decaying marine life
In the ocean, decaying marine life breaks down into organic molecules, including proteins and fats.
Surfactant
Some proteins and fats can act as surfactants. Surfactants have a hydrophilic or “water-loving” end that is attracted to water and a hydrophobic or “water-fearing” end that is repelled by water. This dual nature means that these molecules end up collecting on surfaces – the surface of the water, an air bubble, a particle of dirt, or a droplet of oil, for example.
micelle
Surfactants form spheres called micelles with their hydrophilic ends in the water and their hydrophobic ends pointing toward the surface.
Foam
In the case of sea foam, wind and waves mix the water, and surfactants form micelles around air bubbles, stabilizing them so the bubbles don’t pop right away. This is how sea foam forms!