The Finger of Death is a death sentence for a slow-moving creature like a starfish. Photo: YouTube//Screenshot
Our planet is full of incredible phenomena. One of the most incredible is something called a “finger of death,” a sliver of super-cooled ice that grows downwards from the underside of sheet ice. It has a less-foreboding name too, of course: a brinicle. But finger of death is way cooler.
Brinicles, as the name implies, are a combination of brine and icicles. They’re so incredibly cold that they basically flash-freeze anything they come into contact with. They’re made up of super-salty water called brine. Seawater along the surface of the ocean freezes when the temperature drops enough, but as that happens, salt is forced out into the surrounding waters. That lowers its freezing point, so that it can get super cold without turning to ice. Luckily, they’re relatively rare and don’t occur on scales large enough to alter the ecosystem in a big way.
“I have seen the aftermath in person (the pools of dead animals) and then videos of them actually getting caught,” explained Andrew Thurber, an assistant professor in ocean ecology and biogeochemistry at Oregon State University. “They are a very, very localized problem for animals. They tend to only occur in the shallows, and the species that occur there tend to be both abundant and common. So while small patches of dead animals that result from them, overall they very likely play a minor if any role in the population size of those animals.”
The concentrated briny water is cold enough to freeze the surrounding seawater as it sinks, forming a tube of ice in which the outside is constantly freezing as the inside stays liquid. While it was first observed sometime in the ’60s, the process wasn’t filmed until 2011. Even now, they’re still not entirely understood.
They can grow extraordinarily quickly, too — several meters per day — and when they hit the bottom, they spread out into a sheet of ice. That’s where slow-moving creatures like starfish and urchins are in danger, because if they’re caught up, they freeze almost instantly.
