East Coast - One Of The Rarest Canadian Animals Under Your Feet
Burntcoat Head is a perfect place to explore the Bay of Fundy’s exposed ocean floor at low tide, and see one of its most striking geological features: sweeping red mudstone and sandstone that formed 200 million years ago. It’s also hiding one of Canada’s rarest animals, tucked into tiny almost invisible holes in the rock. Today we learn all about them, their unique evolution, and what a knife edge they’re living on.
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TRANSCRIPT
Exploring the shoreline of the Bay of Fundy, you’ll come across these stunning outcrops of red. They’re deposits of Triassic mudstone mixed with Jurassic sandstone, laid down starting 220 million years ago, now being ceaselessly worn down by the wind and tides into natural sculptures.
Like here on the south shore of the Minas Basin, at Burntcoat Head - incidentally the very spot where the Bay of Fundy’s ‘highest tides in the world’ were actually measured.
It’s so easy to get swept up in the grandeur here that you miss what’s right under your feet - in this case tiny holes in the rock hiding one of Canada’s rarest animals taking full advantage of the malleable rock.
They begin life as free-floating larvae. Just one of thousands of planktonic species at the mercy of tides, currents and predators.
But after about a month they start to settle down. They grow a specialized muscle called a foot, using it to probe the ocean floor for a place to put down roots.
And they’ve got very specific needs: oxygenated water, like the kind constantly churned by the Bay of Fundy’s massive tides. And, red mudstone - like the kind at Burntcoat Head.
When they find that magic combo, they use their newly grown ‘foot’ to dig straight into the rock.
As they age, grow and start to form a shell, they keep burrowing deeper - meaning their hole naturally becomes conical.
Until finally they arrive at their adult form: the Atlantic Mud Piddock. And if the name seems a little ignoble, they’re also known as fallen angel wings for the shape of their shells.
Piddocks are bivalves, related to scallops, clams and mussels. Which is a bit odd because the defining feature of a bivalve is they grow this big strong shell for protection. But… do you need that when you’ve already got a ‘shell’ of solid rock?
In fact Piddocks do seem to be evolving in the direction of ‘who needs it?’. Their bodies grow so big they can’t physically retract them into their shells anymore. And those shells have become so brittle that it’s quite rare to find them. The action of waves against rocks usually pulverizes them.
Their conical homes certainly do protect them, but it also means the piddocks have trapped themselves. They spend their whole lives - on average eleven years - in their burrows.
That means they’ve gotta do everything through that one, tiny hole. To eat, they extend a siphon out into the water to filter feed, catching organic matter as it floats by them. And they have a second siphon to expel waste.
Same issue with breeding. Colonies of piddocks need to release sperm and eggs into the open water and just hope they find each other.
To someone on a stroll at Burntcoat Head, the unique, secretive lives of piddocks make them nearly invisible. You’d have to look out for tiny holes in the rocks or watch the tidepools for little puffs as they clear sediment out of their burrows.
But their very particular habitat also means that this overlooked lil bivalve is one of the rarest animals in the country.
Their need for that specific mix of well-oxygenated water and red mudstone keeps them constrained to very specific spots in the Minas Basin.
So these red outcrops that started forming 220 million years ago are now hosting an incredibly fragile community. Habitat for the Atlantic Mud Piddock is a whopping 1.84km squared. That’s all they’ve got to work with - in the whole country.
It’s only recently that we’ve woken up to just how fragile they are. In 2017, they were finally listed as a threatened species.
Now, there are ongoing efforts to preserve and protect them. At Burntcoat Head, stretches of the shoreline are fully off limits to visitors, to give them free reign.
The battle isn’t just against us encroaching on them. Climate change is bringing more frequent and severe storms that are liable to smother and destroy their red oases.
And it’s gonna be really tough to assess if they’re even recovering. I mean - how do you accurately and non-invasively count a population buried in the rock?
For now, the best the rest of us can do is always mind our feet when walking on the ocean floor and remind ourselves that, more often than not, we’re walking on someone’s home.