You Know the Ocean’s in Trouble When Your Shell Starts Melting

Things are getting really dicey for a little ocean creature called a pteropod. Better known as the “sea butterfly,” this delicate little sea snail is serving as an unfortunate bellwether of the deteriorating state of our oceans. Why?

Conditions in the Antarctic ocean and along the West Coast of the U.S. have become so unnaturally acidic that the shells of sea butterflies are literally dissolving away.

“We did not expect to see pteropods being affected to this extent in our coastal region for several decades,” said Dr. William Peterson, an oceanographer at National Oceanic and Atmospheric Administration (NOAA)’s Northwest Fisheries Science Center, in a NOAA press release.

Damage that’s “several decades” early is a big alarm bell. We’d better pay close attention before it’s too late.

healthy pteropod

A pteropod with a healthy exterior shell. Photo credit: NOAA

What Were Doing to Our Oceans

The chemistry of the world’s oceans is changing, thanks to the carbon dioxide humans continue to spew into our atmosphere. Oceans absorb between one quarter to one third of that carbon dioxide. Over time, it has turned the ocean from a slightly alkaline state to a bit more acidic.

According to some estimates, the ocean’s pH level 150 years ago was about 8.2. It’s now about 8.1. It may seem to be an infinitesimal shift, but it’s worse than it sounds. The more acidic the ocean gets, the harder it is for marine life like oysters, clams and corals to form calcium carbonite skeletons and shells.

In the case of pteropods, the increased acidity of the ocean is actually eating away at their shells.

dissolving pteropod

Pteropod with shell beginning to dissolve. Photo credit: NOAA

“The first thing that happens is the dissolution of their shell,” NOAA’s Dr. Nina Bednarsek told PBS. “Dissolution can be mild, [to] very severe. Once you have it dissolving on the outside, you have to put so much more energy into the shell in order to maintain it. The energy that you would otherwise use for other important physiological maintenance you are putting in the shell maintenance.”

Researchers working off the coast of Oregon, Washington and California in 2011 discovered that over half of the sea butterflies they found onshore were victims of “severe dissolution damage.” Offshore, about 24 percent were damaged.

If we don’t change our ways, by 2050, researchers estimate that coastal waters will be 70 percent more acidic than they were in the pre-industrial era.

The Importance of Sea Butterflies

Pteropods are little swimming snails. They earned their nickname because of the little “wings” they use to swim, which make them resemble graceful underwater butterflies.

The devastating impact of the ocean’s corrosive water on sea butterflies’ shells is not just bad news for the pteropods themselves. A number of other ocean dwellers that rely on pteropods for food will suffer.

surface dissolution of pteropod shel

Closeup of surface dissolution of a pteropod shell. Photo credit: NOAA

“In the Arctic, [the] species get really big,” Dr. Bednarsek told PBS. “A lot of organisms actually depend on them among them birds, fish, whales.”

In certain areas, sea butterflies make up 60 percent of the diet of young pink salmon, for example. Herring and mackerel rely also on them for sustenance. Pteropods are one of the first rungs in the ocean’s food chain. Without them, the other higher links in that chain may not survive.

The influence of industrialized mankind on our environment is undeniably negative. Our reliance on fossil fuels must change if we are to have any chance of reversing these negative impacts.

The entire ocean-based food chain now depends on us. We must make things right before it’s too late.

Photo credit: Thinkstock


Carrie-Anne Brown

thanks for sharing :)

Janice Thompson
Janice Thompson3 years ago

Clean up our oceans.

Debbie Crowe
Debbie Crowe3 years ago

Stop relying on fossil fuels!!

Mark Donners
Mark Donner3 years ago

Anything dependent on humanity is usually doomed.

federico bortoletto
federico b3 years ago

Grazie per la condivisione.

Jennifer H.
Jennifer H3 years ago

What a mess we have created and with so many deniers in denial I don't see any hope for improvement.

Elizabeth Nipper
Beth Nipper3 years ago

So sad. So few believe. :-(

Graziella Veri
Graziella Veri3 years ago

WOW...but is also horrible and terrible...sad.Thanks for sharing!

Melania Padilla
Melania Padilla3 years ago

Just one of the consequences of ocean acidification....

Manuela C.
Manuela C3 years ago

How sad...