Of tides and maps and worm poops

The stretch of beach that I wandered around this week while the sun shone (we're back to cloudy daytime skies and low tides after sunset again) is an almost-flat rock slab with hundreds of large rocks scattered on top, glacier droppings, not part of the base rock. The intertidal zone reaches out some 200 metres, and then the bottom falls away.

Google map view. The usual intertidal zone goes out to the white wave line. Most of the rocks line up, leaving large, smooth areas of rock. 

(I fell down another rabbit hole. I've spent all afternoon crawling around a map of the sea bottom  of this area. It is meant for boaters and fishers, but it includes all sorts of things in the intertidal zone; pilings, shipwrecked hulks — the Matane is one, another I'll go and look for —, large rocks, lights and docks and waves and kelp beds and mud flats ... The lighter area on the Google map corresponds to the 2 metre line on the boating map.)

The first bit of this beach, near the shore line, is sandy and the sand is busy.

Worm poops. Lugworm fecal castings. The worms, Abarenicola spp., live in a J-shaped burrow head-down in the sand, where they swallow sand, digest the organic detritus, then eject the cleaned sand onto the surface.

One worm's pile.

A periwinkle snail, Littorina sitkana. With a red alga I haven't been able to identify.

Snail trail. Lumps in the sand are his cousins, already in hiding until the water comes back.

Two limpets. Conditions in the intertidal zone for animals that don't hide at low tide are harsh, and these limpets' shells are badly weathered.

On this beach, I didn't see any sand dollars; they hang out in the mid to lower intertidal zones, and here, the rock lower down has, at most, a slight dusting of sand. Nor were there any moon snails, which also need deep sand.

Next: the rock dwellers.

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La playa que visité esta semana mientras brillaba el sol (y ahora ya regresaron los dias nublados y las mareas bajas nocturnas);  la playa es una placa plana de piedra, y encima están esparcidas cientos de rocas sueltas, estas abandonadas por los glaciares. La zona intermareal se extiende por unos 200 metros, y aquí el fondo se hunde y desaparece a la vista.

    1. Mapa de Google. La zona intermareal alcanza hasta la linea marcada por las olas. Las rocas se arreglan en lineas rectas, dejando amplias areas limpias, lisas.

(Me distraje otra vez. He pasado toda la tarde estudiando un mapa del fondo del mar de esta zona. Está orientado a los navegantes y pescadores, pero incluye detalles de cosas que se encuentran en la zona intermareal: pilotes, barcos hundidos — uno es el Matane y hay otro que iré a buscar —, rocas grandes, faros y muelles y olas y lodazales y sitios donde crece el quelpo ... El area más claro en el mapa de Google corresponde al nivel con menos de 2 metros de agua en el mapa para navegantes.)

El tramo superior de esta playa, cerca de la orilla, es arenosa.  Y la arena está poblada.

    2.  Roscas fecales de gusanos poliquetos. Estos gusanos, Abarenicola spp., viven cabeza abajo en una madriguera qque hacen en la arena en forma de J; allí ingieren arena, digieren la materia orgánica, y luego expulsan la arena limpia en la superficie.

    3. Una rosca de uno de estos poliquetos.

    4. Un caracol Littorina sitkana, con algas rojas que no he podido reconocer.

    5. La huella de uno de estos caracolitos. Sus primos ya están escondidos bajo la arena, protegidos hasta que regrese el agua.

    6. Dos lapas. Las condiciones en la zona intermareal para los animales que no se esconden en las horas de marea baja son difíciles. Estas lapas tienen las conchas muy desgastadas.

En esta playa no vi ningún dólar de arena; se congregan en las zonas intermareales mediana y baja. Aquí en esta playa las rocas más bajas tienen acaso un salpicón de arena.  Ni tampoco había ningún caracol luna, que también necesitaría una profundidad amplia de arena.

Siguiente: animales de las rocas.

Mountain peaks on the flats

More oldies dug out of the hard drive. Just because.

Worm poop mountain, Boundary Bay beach.

And barnacle peak, White Rock beach.

Good excuses

Why it takes us an hour to walk one kilometre, on flat sand. It's easy going, with nothing to slow us down.

Boundary Bay, with Mount Baker, at low, low tide.

But we keep stopping to take another photo.

Clam in a tidepool, with refracted light, through a few inches of water.

Empty clamshell

Crab molt

Foot long polychaete worm, from my tank, returning to home base.

In every tidepool, hundreds of tiny, darting fish fled at our approach. These ones were "escaping" from Laurie, while I stood off to the side, without moving, except for my shutter finger.

Feather, pink and brown clam shell, worm poop, bird footprint, and a few sandy snails. As found.

Detail of feather. Worth clicking to see the tips full size.

Wave-carved sand patterns

Lugworm egg case. Most are large oval bags; this one is almost round. With worm hill and poop.

Tiny Baltic macoma shell. Most of the ones on this beach are pink. Very fragile; half the ones I bring home don't make it.

Speckled stone, with dwarf eelgrass, Zostera japonica. The stem just to the left of the stone has a row of seeds in a half sheath.

Spying on an underground community

So, I've been trying to take photos in the dark. Not dark dark, midnight dark, but in shadow, illuminated only by a weak, yellowish overhead light, and dimmed even more when I used an auxiliary lens. And I couldn't use flash*.

See, the floor of the aquarium is covered with 2 inches of sand (more or less, as the crabs dig out valleys and hills). I brought the sand from their home territory, in the upper intertidal zone of Boundary Bay, draining off the fine sediment and muck before I used it. It was "live" sand; I reserved a half-cupful and left it overnight in a white bowl. In the morning, tiny, pinpoint snails were climbing the walls, and a few worms had re-established their tubes. Their tentacles, fishing for food, were only visible with my hand microscope.

All to the good; worms in the sand clean up tiny bits of food that the hermits and crabs scatter. (Messy eaters, the lot of them!) Along with the mud snails and Nassas that plow through the sand looking for food, they help to keep the sand oxygenated, so that it doesn't develop those stinky, black dead zones that we find on the beach where the sand is too compacted.

Within days, the sand in the aquarium was riddled with hair-thin worm burrows. Some are right up against the glass wall, and I have been watching them.

The problem is, they don't like light. Very emphatically, they do not like it. Move the lamp so that light falls on the glass, and they're gone, retracted back into the dark sand. They're fast. All I usually see is a hint of moving colour at the bottom of the burrow, then nothing.

The camera is better than my eyes, even here. I set the camera down an inch from the glass, focused, held the focus so that the worms that fled the red focusing light could return, then pressed the shutter. Click ... ... ... ... click. I didn't release the shutter until the second click, to avoid shaking the camera while it worked on the scene. (The little pocket Sony was better at this than the bigger Nikon.)

Here are the results.

What the camera saw in the dark. Burrows and red worms. Some light percolates down through the top half inch of the glass wall.

I get the camera ready, finger on the shutter button, and turn on the light. This is what I see:

Empty burrows. A hint of red at the bottom of the long burrow on the right; a slowpoke worm.

Clean, nicely rounded tunnels. The worm wobbles its body back and forth to shape the sides. 

The tunnels are now about as wide as a line written by a fine lead pencil. The worms are obviously eating well and growing fast. The longest burrows are about three inches long, taking their meandering into account. They each open at the top onto the surface of the sand, and I have seen a couple at the opening, fishing.

I cropped the clearest photos, lightened them 'way up, and saturated the colour in the worms to compensate. As far as I can tell, there are three species of worms.

A long, smooth, round worm, lightly marked on the red. Lugworm?

A couple more of the long ones, and a short, fat worm (or segment of worm), much redder. It has some projections at the sides, parapodia, probably. Another polychaete?

Another of the long, smooth worms, head and tail both in the sand.

In the top right corner of the first photo above, there is a stripy worm. Here it is, magnified.

There were also a few translucent, unmarked, very smooth-skinned worms, just slightly pinkish. The cameras absolutely refused to take notice of them. At this size, I can't identify any of them.

And no wonder I can't find any on the beach; they are too fast for human hands, mostly too small for human eyes even when I do dig them up.

* The flash would have bounced off the glass, and made everything inside invisible.

What I will never understand ...

... is how, whenever I dig for worms on the beach, no matter how fast or furiously I dig, I hardly ever find any large enough to see with the naked eye.

And yet, the millions upon millions of worm poop piles are topped with ropes of worm poop icing fatter than the length of most of the worms.

For scale, the mud snails are 1/2 to 1 inch long. The grass is dwarf eelgrass; its blades are  about  1  1/2 mm. wide.

Half-submerged mound, a couple of inches high.

That's a lot of poop for a tiny worm!

Upper intertidal zone, Boundary Bay, mid-September.

Ice cream worm

For years, I've been seeing lugworm poop on our beaches; I've dug down below the mounds often, the last time about a foot down. I've never seen a lugworm, except in books. Until this afternoon.

At the top of the intertidal zone, by the boat ramp at Beach Grove, I turned over one of the broken paving stones, and there was my first lugworm. So easy!

Neapolitan lugworm, Abarenicola pacifica. The head is partially hidden in the sand ; it's trying to escape the light.

Here it is, clean, digging in. Plus an unidentified worm, probably a ribbon worm, also burrowing out of sight.

The head end is greenish, the mid-section pink, and the long, thinner tail end is, at first glance, a creamy colour; this may have inspired the name, "Neapolitan"; it reminded someone of three-layer ice cream. I see the tail as more green and yellow, with a pink stripe down mid-back.

Along the sides of the mid-section are the bright red gills, just visible in this photo, half-buried in the sand as it is.

With the sand washed off, this is a beautiful worm. 

Lugworm castings, further down the beach.

I never thought of turning the paving stones before. Of four that I flipped this afternoon, two had surprises. Tomorrow, I'll post photos of the second.

Two mountains

Worm mountain:

Towering above the plain.

People mountain:

Mount Baker, up to its old flying tricks again.

From another low tide at Boundary Bay.

October colours, with mud for contrast

The mud flats. It's been a while since we last squelched across them. This Sunday afternoon felt right; we parked near the inner reaches of Boundary Bay and ventured out. The tide was low and the afternoon warm. A couple of kids, far out on the mud, were digging for clams, using only their hands. (I talked to them, and showed them how to find the exit tunnel of a mud dweller. And were they ever a mess! Mud critters, themselves.) A man threw sticks for his dog in the distance; other than that, the flats were quiet.

Those white spots are golf balls. There were several dozens scattered about, some new, some old. How and why they got there, I don't know.

Across the water, Mount Baker was practicing its levitation techniques. And hundreds of sandpipers fished for goodies far away along the tide line.

Mount Baker, flying. Sandpipers, wading.

The mud was not too deep here. It squished between our toes and spattered our legs, but didn't try to steal our sandals. We collected pink Macoma shells (with the two flatworms, but I didn't know that) and washed them off in little pools. We left the lugworms and snails in peace.

Lugworm heaven.

Lugworm poop.

Snail trails.

Trail blazers.

Under this volcano, a clam hides. I dug one out; it was flat and brown.

We walked to the edge. The tide was coming in, racing, the way it does here; we beat it back to the shore, and a passageway to the street. The fall foliage was a welcome sight after all that grey-brown.

Orange, yellow, red. And a pair of mailboxes.

Rose hips.

A pair of dragonflies, darners, were visiting the fruiting heads of sumac. They ignored the leaves. I wondered if they were feeding on insects feeding on the fruit.

Darner, possibly the Blue-eyed darner. A male, going by the three appendages on the tail end.

Red, yellow, green, blue.

Back at the car, a neighbourhood cat watched the street from our roof.

Whitey

We washed our feet under a handy tap beside a driveway, and went to Tim Horton's.

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Watching where we step

On a mile-wide, featureless, sandy beach, what is there to see, besides sand and sky? Plenty. But it's mostly in hiding. I've been having fun blowing up our photos of Sunday's walk to full size, to see what we missed.

Sea lettuce and a mudflat snail, Batillaria attramentaria. No telling what's underneath.


Brown seaweed, probably a dulse. Eelgrass and roots.

So far, so good. Eelgrass and seaweed are easy to see. But look again! See those little yellowish dots on the eelgrass? They're egg cases, possibly of the Black Dog Whelk, Illyanasa obsoleta*.

Here are some more, doing their best to blend in with the bubbles.

Brown tuft, navel-lint algae. With eelgrass and snail eggs.

The snails are even better at hiding; they burrow right under the wet sand. I dug a few out; mostly Black Turbans, and a whelk or two. One on the upper left, below, looks like a mudflat snail, going by the shape.


In a photo of seaweeds and eelgrass, I found this tiny collection:

White tube discarded by a worm. And what looks like whelk eggs. (Nucella sp.)

If I had seen this at the time, I would have taken a close-up. But they were so small, I missed them even on the first two examinations of the photo.

This tangle of weeds and -- something -- is intriguing:

What is that red, segmented, tentacled thing? Worm or weed?


A close-up of the end, with "tentacles". Some kind of spaghetti worm? **

This is a worm, at least. We found it writhing in an inch of water. It's about 6 inches long.

Red-banded Bamboo worm, Axiothella rubrocincta. The red rings are bristled. (Barely visible.)


Clear view of the tail end. The head is already back under the sand, and digging fast.

Their tubes were scattered here and there around this area of the beach, mostly poking just an inch or so above ground. The worms stay in these tubes; I wonder why this one was on the surface.

On the opposite side of the bay, at Boundary Bay Beach (and this is all Boundary Bay, but this side is Crescent Beach), the sand is dotted with the fecal castings of lugworms. On the Crescent Beach side, the coils of worm poop are less frequent, smaller, and finer. Look for them around these geoducks:

Pacific geoduck, Panopea abrupta. Up to 9 inches across the shell, and 20 lbs. Lifespan: 168 years!

When I touched this geoduck (pronounced gooey duck) with a toe, it retracted itself back under the sand, squirting at me as it went.

A horse clam, covered with algae and seaweed, and accompanied by grey mounds of worm poop.

(Update: I had identified this as a geoduck. I was wrong. Looking more closely at the siphon mouth, I realized that the edge of the mantle is tentacled; this identifies it as the gaper, or horse clam, Tresus nutalli. (The tentacles are green, which distinguish it from T. capax, where they are gold. I still think, though I could be wrong, that the first one is a geoduck. Neither it, nor one other similar one that we photographed show any sign of tentacles, and the other one has the characteristic one siphon, two openings of the geoduck.)

Look in front of the clam siphon; that brown coil is not lugworm poop; it looks more like a ribbon worm of some kind.

Mouth of the gaper clam.

One last critter. There were quite a few of these. But we never saw them unless we were about to step on them; then they shot out of the sand, sped a few feet away, and -- disappeared, even though we were looking right at them. One moment they were swimming, the next, there was not a trace of them.

Can you see the tidepool sculpin here? I have increased the contrast to make him stand out.

Tidepool sculpin, Oligocottus maculosus. Supremely camouflaged.

So many new things! So much to learn! What fun!

* Photo in Marine Life of the Pacific Northwest, MC198, p.228. Also, see my last year's post, No boots, no bags, some goodies anyhow, for macro photos.

** It's really an eelgrass root, with its rootlet "tentacles".

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