Consider the mussel. Not the invasive zebra or quagga mussel – those freshwater invasives that plug sewers and ruin turbines in the midwest – nor the foul tasting ribbed mussel that buries itself in salt marsh mud and tastes just like it. No, consider the blue mussel, Mytilus edulus – “edulus” from the latin: edible.
So edible, in fact, that Moules et frites is one of Belgium’s national dishes. A Belgian restaurant in Washington D.C. we ate in once had what seemed like dozens of delicious-sounding variants on the menu. Moules marinière, Moules natures, Moules à la crème, Moules parquées, Moules à la bière, Moules à l’ail, etc. – the blue bivalve seems to electrify the culinary imagination.
Once steamed open, there are two distinctly different types of blue mussels – yellow and orange. They taste identical and there are about equal numbers of the two colors. Turns out that the creamy white ones are male while females are described as being of a “warmish orange”. It makes one wonder if our species’ propensity for racial bigotry might evaporate if the sexes of us humans were similarly divided by color.
Blue mussels epitomize the word sedentary – spending their adult lives stuck fast to the surface they first settle on – but “sedentary” doesn’t do justice to the tenacity with which they adhere to structure. Wresting them off the rocks to which they typically anchor themselves can be nearly impossible thanks to a two part system involving a unique glue laid down at the ends of multiple thread-like structures known as “the beard” to mussel eaters and byssus to marine biologists. For eaters, the beard is a bother. It feels like a foreign body in the mouth and tastes and feels like chewing on sewing thread. Attached to a muscular organ in the muscle’s innards it needs to be forcefully removed before the mussels are cooked. But to bioengineers and inventors, what byssus is made of and how it is formed is a beckoning path to fame and fortune. The threads are unique among fibers since they combine bungee cord elasticity (stretchable to 160% of original length) with Herculean strength (5 times stronger than the human Achilles tendon) – an extremely unusual combination of fiber properties. https://www2.clarku.edu/departments/biology/biol201/2002/LBrentner/byssal_threads.html,https://www.npr.org/templates/story/story.php?storyId=124319594
How byssus fibers adhere to rocks has been another active focus of scientific investigation. There are mighty few good glues that can be used under water, yet mussels know how to make an excellent one. Sadly, they never patented the process. Now, after slicing, dicing, crushing and otherwise murdering to dissect bushels of mussels, bioengineers from Genex and Bio-polymers have done just that. Soon heart surgeons may have a glue to close bloody wounds, the U.S. Navy may be doing underwater glue repairs and we may someday see a ruptured Achilles tendon replaced with a byssal cable stuck to our heel and calf muscle with mussel glue! Stockholders in Genex and Biopolymers will smile but it’s unlikely that marine ecologists studying mussel dieoff will see big grants based on mussel royalties.
We H. sapiens are not the only ones with a taste for Mytilus edulus. Like our own species, a blue mussel typically spends its youth drifting around aimlessly – though these little mussel trochophores, veligers and pediveligers face armies of filter feeders ranging from sunflower seed-sized crustaceans to schoolbus-sized whale sharks. And even after they settle down and stick themselves fast to a huge chunk of granite they remain vulnerable to being harvested and boiled alive by us, swallowed whole by diving ducks, crushed by the toothy jaws of blackfish, drilled into by dog whelks, or subjected to the dismal fate of being pried open by a starfish’s arms and then hosting that creature’s whole stomach which the echinoderm has everted onto the mussel’s newly exposed innards.
As a child, summering on the Rhode Island coast where the rock-drop from receding glaciers makes perfect mussel habitat, I could pick a meal’s worth in half an hour. That was well before they started showing up in supermarket seafood cases in the ‘70’s followed soon after by appearances in NYTimes recipes. Since then, I’ve watched their price steadily increase and their numbers among the rocks steadily dwindle to the point that a summer supper of wild mussels is now almost unheard of.
Speculation about the causes of the decline includes over-harvesting, pollution, ingestion of microplastics, higher water temperature, excessive non-human predation, degradation of native DNA by the escaped gametes of coddled farmed mussels, a mussel epidemic or some villainous mix of all these usual suspects. Scientific consensus seems to be settling on the fact that the decline’s causes are multifold and man-made, a fate now being suffered by untold numbers of other species. One peer reviewed paper documented that the southernmost edge of the blue mussel’s range drifted 350 km northward from Cape Hatteras North Carolina to Lewes, Delaware between 1960 and 2010. In Rhode Island now, if we find any they’re hidden in deep crevices on the northeast side of rocks – protected from the intense heat of the afternoon sun. And now when we bring home a meal’s worth of mussels, they come from farms in colder Canadian waters.
It’s humbling to consider the mussel while watching surf crash on the Rhode Island boulders where a few still remain . Here is a species that seems to have been around for about 200 million years. It spends its infancy drifting defenseless in the ocean currents. Then after two or three months when it finally decides to settle down it typically chooses a spot regularly bashed by three or four foot waves every 15 seconds and by twelve or thirteen foot rogue rollers whenever an angry coastal storm comes along – and apparently loving it. The fact that this hardy creature is now in trouble, as are so many other fellow travelers on spaceship earth is telling us something.
Credible investigators https://www.livescience.com/24805-undiscovered-marine-species.htm put the number of different species in the ocean at about a million, with about three quarters yet to be discovered! Meanwhile we go on turning up the ocean heat with our greenhouse gasses and producing plastic from fossil fuel at a geometrically accelerating rate with annual production rising from zero to 400 million tons between 1950 and today https://ourworldindata.org/plastic-pollution. One can only wonder what kind of miraculously useful substances like byssus and mussel glue will come from those yet to be discovered marine creatures if we can just get to them before warmer oceans cooks them out of existence or we clog them to extinction with plastic.