Winter shores

scores of intertidal invertebrates, and a nifty little fish

On a nice day of semi-sunshine and a soft breeze, we played hooky from whatever else we were supposed to be doing and spent several hours at one of our favorite activities—just poking around in some potentially interesting spot to see what we could see. What better way to spend a winter morning than doing a favorite thing with two favorite companions who like to do it too!

This time we went to the west side of Douglas Island and prospected along those bouldery, cobbly shores that pass for ‘beaches’ here in Southeast. We found a moderately low tide during daylight hours (no easy task in winter!) and cruised around peering in rocky crevices and gently turning over rocks (and turning them back again, of course).

The top of the beach had a deep berm of crushed clam and mussel shells, clear evidence of heavy-duty wave action. The beach fringe is the only kind of place I’ve ever seen the occasional native Douglas maple around here. The one we found was sizable and showed several arrays of sap wells in the bark, where a red-breasted sapsucker had foraged, perhaps last summer.

Getting close to the water’s edge required scrabbling over lots of sharp-edged barnacles and mussels while trying to protect hands and expensive rain pants. Deep in the crevices in the bedrock, we spotted some yellow sponges (I’ll spare you the sometimes-ponderous scientific names, even when we know them). There were three kinds of chitons, a few limpets, some large, lumpy red and green anemones, and many patches of pink coralline algae. We noted two (unknown) kinds of eggs stuck in clumps to the rock, so at least two kinds of critters were reproducing, even in winter.

Wedged between cobbles and under flattish rocks were rich aggregations of small beasts: hundreds of little six-armed sea stars, dozens of small tar-ball sea cucumbers and a few bigger false white sea cucumbers. We found a few of the clams known as hiatellas, burrowed down between the rocks with just their red-tipped siphons showing. Something entirely new to me was the barnacle-eating nudibranch; nudibranchs are actually molluscs that don’t have a shell, and many are brilliantly colored. This one, however, was dusky brown and in the act of guzzling up the juices of a hapless barnacle.

Scattered here and there were some very large mussels, much bigger and heftier than those in the usual crowded patches spread over the beach. These big ones were half-buried in sediments between the cobbles and invariably were solitary. They were a puzzlement: are they just common blue mussels that escaped from the crowds and the competition of many neighbors, so they could grow huge, or are they another species altogether? If so, what species? Southeast harbors the big California mussel in certain places, especially in more outside waters, but these specimens didn’t match the description for that one.

We also found a spectacularly red ribbon worm—a mighty predator that can get as long as eighty inches, although ours was much smaller—looking rather like a limp, soggy, worn-out shoestring. Ribbon worms typically feed by extruding a proboscis armed with a sharp dagger. After stabbing a victim several times and perhaps injecting a paralyzing toxin, the proboscis is retracted and hauls the prey back to the mouth. (One species feeds by climbing down the siphons of clams; imagine being a clam and feeling ones of those things crawling into your insides to do you in! Let’s hope our clams don’t have to deal with that one!).

Tidepools held hermit crabs of all sizes, some with capacious borrowed shells for their housing, but others with woefully inadequate covers for their tender bodies. There were some beautiful green burrowing anemones with banded tentacles, some scale worms, and several tide-pool sculpins of various sizes. Small snails called margarites and a few periwinkles were not common and we found only a few of the larger predatory snails that like to feed by drilling through the shells of clams. We discovered two uninhabited tubes of the so-called tusk worm (another new thing for me!). These tubes are curved cones (i.e. shaped like a tusk) built of tiny sand grains all stuck together so tidily that the surface is smooth. The worm typically lives head-down in the sediments, lapping up detritus as food, with the pointed end of the cone up.

The best prize was a small fish that we’d never seen before—or heard of, for that matter. Just a few inches long, it curled up in the bottom of a small tide pool. We caught it and put it in a water-filled plastic tub so we could inspect it. A strange-looking beast, it was— dark brown in color, a bulky tadpole-like body, much wider than the rear end, a flat catfish-like head with tiny eyes, long fins on its back and belly and wide pectoral fins. When we checked the books, it was obviously a tide-pool snailfish, which eats amphipods and isopods and other invertebrates. If we’d known to do so at the time, we’d have looked at the underside of this fish, where we’d have seen a sucker-disc made of converted pelvic fins. These fish can cling to kelp fronds when resting away from rocky pools. Sadly, I have so far failed to find out anything about its ecology and behavior.

Back on land again, we noted otter latrines in the usual locations on rocky headlands. And—another ‘plus’—a three-toed woodpecker neatly flaking bark chips off a scrawny hemlock tree, unperturbed by our presence. The yellow patch on the front of the head marked it as a male.

Another good day—not merely above ground (as they say) but outdoors, seeing and learning and sharing.

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