A Guide to Crustaceans, Bivalves and Molluscs, or Why You Should Be Eating Exoskeleton-Bearing Aquatic Invertebrates

by Mark Sisson
Mark’s Daily Apple

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I grew up in a coastal fishing village in Maine, and one of my favorite memories is being out on the flats at low-tide, digging for the clams that would accompany our occasional lobster feasts (back when lobster was well under a dollar a pound). I can still feel the excitement of pulling that clam rake up and looking for the tasty bivalves that would soon become the first course.

We humans like our shellfish. Nearly every coastal region which hosted humans features massive shell collections, often called shell heaps, or middens. You've even got inland piles, like the 11,000-year-old midden full of snail shells in inland Vietnam, indicating that even inlanders knew shellfish were worth eating. Back in my marathon training days, I recall running a mountain trail in Woodside, CA, ten miles inland, and coming across layers of thousand year-old strata embedded with all manner of seashell left behind by the coastal Indian tribes. Because the entirety was just full of seashells, you had to look closely to discern the individual shells. These folks definitely liked their shellfish.

Recounting a classic Weston A. Price observation, Chris Masterjohn describes how two perpetually warring New Guinean tribes would broker temporary peace to trade shellfish for sweet potatoes. The upland tribes would put aside the spears and bring down some tubers, while the coastal tribes would relent and offer shellfish. It was a beautiful arrangement, far more harmonious than the alternative (which sometimes occurred) – the highlanders selectively hunting and eating the livers and organs of fishermen of the coastal tribes.

But why? What can explain the persistent shell middens all over the world, both inland and on the coasts? Why were there so many seashells embedded in that Woodside strata? What's so great about shellfish that it stops multigenerational tribal warfare in its tracks and drives sweet potato eaters to prize the organs of fishermen who eat it?

They're tasty, sure, but I wouldn't put oysters, mussels, and clams over a grass-fed lamb shoulder roast, and I doubt the flavor of those New Guinean fisherman livers reflected the shellfish content of their diet. No, the taste isn't the driving factor. It's the uniquely dense nutrition inherent to most shellfish. Since they spend their lives immersed in mineral rich water, they're excellent repositories of those same minerals, including zinc, iodine, selenium, and magnesium, along with vitamin A and B-vitamins (especially B12). Plus, when we eat shellfish, we're eating the entire animal (except for the shell). All that muscle meat and digestive tissue and organ mass slides right down. Humans can get these nutrients on land through other animals and some plants, but rarely can they get them in such a concentrated, easy-to-consume form. And you all know how much we like to make things easy for ourselves.

Let's go down the list of species and make a case for including shellfish in your diet:

Oysters

The most nutrient dense, the most expensive, the perfect accompaniment to lemon and hot sauce, oysters are truly the stars of the shellfish world. Recent evidence of an early "oyster bar" puts our infatuation with the bivalves at around 125,000 years old, which is a pretty strong track record. The oyster's reputation as an aphrodisiac may have ground to stand on, as they are the single greatest source of dietary zinc, which our body needs to make testosterone.

Just four medium sized Pacific oysters supply a smattering of B-vitamins (including over 1000% of daily B12), 1200 IU of vitamin A, a third of daily folate, almost 7 mg of vitamin E, 3 mg copper, 280% of daily selenium, and 33 mg zinc. That comes with 18 g protein, 4 g fat, 1.5 g omega-3, 0.1 g omega-6, and 9 grams of carbohydrates.

At an Asian supermarket, I can buy those four oysters, still living, for $0.80 a pop. Or, I can head down to Malibu Seafood and pick up some for a couple bucks each. As to whether farmed oysters, which make up 95% of the market, are okay, they're fine. If you remember from last time, I described how most farmed shellfish live totally "natural" lives, only instead of being attached to a rock they're attached to an artificial construct. Same water and food, though. Eat these guys raw and living for the full effect (plus briny goodness). Canned, smoked oysters are also an option.

How to open oysters.

Clams

As a New England native, I'm contractually obliged to sing the praises of the clam. Now, they aren't quite as nutrient-rich as oysters, but they're still worth eating for a few reasons. First – the texture. Some people hate the chewiness; I love it. I can understand if you get clams cooked to the consistency of rubber, as many restaurants do, but not every food has to be tender. Frankly, I'd find it a little unsettling if clams just disintegrated in my mouth. Second, the versatility. Clams definitely have a flavor – they aren't blank canvases – but it's a flavor that lends itself to a lot of cooking styles. Spicy stir fried Asian clams? Yep, works. Steamed with butter, garlic, and white wine? Great stuff. And of course you've got New England clam chowder, which – by itself – justifies the presence of clams on this planet.

They're also nutritious. Fifteen medium raw clams (mixed species) gives a nice dose of vitamin A, B12, selenium, magnesium, and iron, plus 31 g protein, 7 g carbohydrate, and 300 mg omega-3.

Most clams are farmed, and that's okay.

Try making arctic char chowder, only with clams.

Mussels

When I was younger, mussels were more of a low-end shellfish that I avoided (after all, you could find scads of them clinging to every dock piling on the East Coast). With their appearance on more gourmet menus lately, I've taken a shine to them. In the shell, cooked in white wine, garlic, and butter, with about a cup of savory mussel broth left over is just incredible and super easy. Fast, too. It only takes me ten minutes to throw a big batch together. In fact, I could probably squeeze one in right now... Great. Now I'm hungry for mussels. Hold on while I fix some.

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June 25, 2011

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