Recently, it seems that my news feed has been littered with cases of whale carcasses washing up on popular beaches. On the 4th of July, a heavily decomposed whale carcass washed up on a popular Martha’s Vineyard beach. A few days before that a beloved humpback whale named Wally washed up on a Las Angeles beach. And last week a humpback whale named Snowplow washed up on a beach in New Hampshire.
It’s always a sad occasion when such charismatic animals die, but it’s also a great opportunity to engage a wider audience about what these animals face in the modern ocean and how truly majestic they really are. In fact, when I asked my mom to head out to her local beach last week and take some photos of Snowplow the humpback whale, she reported back about how amazed she was by the size of the animal. And this is after suffering through decades of listening to me yammer on about the awesomeness of whales and being forced to sit through who-knows-how-many whale watches with me. (Sorry, Mom!)
And while it seems like we’ve been hearing about a lot of whales on beaches over the past few weeks, if we consider all of the whales in all of the world’s oceans, we might expect to see a lot more whale carcasses.
So where do they go?
The bodies of dead whales are actually hugely ecologically important in the world oceans. If the body sinks to the ocean floor in shallow waters, it will generally be consumed by scavengers. But the real action takes place in deeper waters far from land.
In most areas of the open ocean, there isn’t really very much. Of anything. So when a whale dies, it actually creates something of a fishy attraction at sea. Generally it will float at the surface for awhile, providing food and shelter to various marine creatures. But eventually it sinks to the ocean floor. And that’s when the action really starts.
Whale falls, the term given to carcasses of large whales that have sunk to the deep ocean floor, create complex deep sea ecosystems in an otherwise barren landscape. And because of this, they attract a diverse array of unusual creatures including giant isopods and the almighty hagfish.
Some of you may know the hagfish as one of my favorite species of fish – second only to the Mola mola. If you’re questioning their awesomeness, check out this video.
These ecosystems are especially important – and scientists are especially interested – because they allow for the study of something called ecological succession. This is the process ecosystems experience as they change over time. And whale falls offer great opportunities to study these changes. Scientists at the Monterey Bay Aquarium and NOAA have been studying these changes off the coast of California and have identified at least three stages of succession at whale falls.
First, species like hagfish and sharks consume the soft tissues. And there’s a lot of it on a large whale – it can sometimes take several years for these scavengers to demolish a large whale.
Next, less mobile animals, including crustaceans like the giant isopod or polychaete worms, colonize the bones of the whale and the surrounding area to extract every last morsel of blubbery goodness from the area.
Finally, a specialized type of chemosynthetic bacteria colonize the whale fall. These chemosynthetic species are able to generate their own food – like plants – in the absence of oxygen, using only chemicals like hydrogen sulfide. Instead of using sunlight and oxygen, they’re using fat from the whale bones and sulfur naturally occurring in the oxygenless depths of the ocean – talk about awesome!
Anyways, these bacteria form mats that also provide food for other invertebrates like mussels, clams, and snails. And here’s the even crazier part – there are so many nutrients in the bones of whales that this final stage of succession can last up to 100 years!
So next time you see a whale, just think, even after that majestic creature has died, it’s body will continue providing the marine environment with life for another century