When my shovel started turning up unusual purplish clams, I tossed them back in the hole with hardly a thought. But as the number increased and invasive species became news,

I began to suspect things were going to change, one way or the other.

The microscopic offspring of purple varnish clams arrive in bilge water that collects in the bottom of boats and ballast water taken on by ships carrying light cargoes. Ships pump it in one place and pump it out another, efficiently transferring creatures all over the world. It’s a practical solution that’s created a huge problem.

We should have seen it coming. The term bilge water is used to describe lies, drivel and nonsense, and as a name for slimy characters.

The idea of foodstuffs imported in bilge water doesn’t immediately whet the appetite. But realizing I’ve been mindlessly selecting the purple varnish clams for survival by leaving them on the beach to reproduce while removing butter clams and little necks, last week I pushed squeamish emotion aside and applied cold logic. Somewhere in the world, somebody must eat this species. I would too.

Nervous, sweating, ready to bail at the slightest sign of odd behavior, bad smell or questionable taste, I dug a dinner’s worth of purple varnish clams, left them overnight in saltwater and cornmeal, and cooked them. Then I ate them. With melted butter, naturally.

I lived. I can still move my arms and legs. I pronounce purple varnish clams perfectly good to eat. They taste much the same as butter clams, maybe a little more tender. Folks who find clams rubbery might actually like the purple ones better.

A constant stream of news tells of problems with invasive species. Land invaders are often introduced intentionally by gardeners smitten with lovely flowers. Sometimes the plan goes awry, as anyone who’s battled Himalayan blackberry can attest.

Marine invasives are a different kettle of fish. Unseen, beneath the surface, they’re spreading every bit as aggressively as our thorny upland enemy.

The purple varnish clam pushes out little neck and butter clams. The European green crab eats the food that usually nourishes juvenile Dungeness, zebra mussels and sea squirts colonize whole bays.

Legal and technical fixes such as filtering ballast water are coming, but the creatures are already here, merrily multiplying.

Join the various efforts to stamp out invasive species. Cut back blackberries, dig up spartina, wash your boat before taking it from one body of water to another, don’t dump that pet fish your kid is tired of into the lake. And, get over the idea that invasives aren’t good to eat.

If we eat them instead of the natives, the native species can recover. If every man, woman and child on Whidbey picked a gallon of blackberries each August and ate several pies (Twist my arm!), the next generation might look at old photos of the island and ask “What are those stickerbush berms along the highway?”

Same with the other purple invader. When digging clams, take the purple ones along with the little necks and butters.

Or better yet, eat only the purples, plant the natives back in the sand with their little butt cheeks down, (take a look, you’ll see what I mean.) Fill in the hole.

On Maui recently, some top chefs took part in the “Invasive Species Cook-Off,” serving a fish that threatens coral reefs.

Whidbey needs an annual “Eat the Invaders” bash. Local restaurants could serve Green Crab Bisque, Zebra Mussels Mariniere and Purple Clam Chowder. We could have a cook-off: entrants devise recipes for non-natives, cook them up for judges and win fabulous prizes, such as trips to the homeland of their ingredients. Dessert? Blackberry pie of course.

Want to share a technique for cooking an invasive? Send it to tidallife@whidbey.com.

Information about invasive species:

Department of Agriculture, www.invasivespeciesinfo.gov/toolkit/detgrcrab.shtml”www.invasivespeciesinfo.gov/toolkit/detgrcrab.shtml.

Dept. of Fish and Wildlife, wdfw.wa.gov/fish/ans/index.htm.

Check for beach closures before digging:

Dept. of Fish and Wildlife Shellfish Hotline, 1-800-562-5632.

For hands-on clam digging lessons check out the WSU Beach Watchers “Digging for Dinner” series.

The next class meets from 9 to 10 a.m. Saturday, Aug. 16 in the Double Bluff Beach parking lot in Freeland.