Wednesday, November 01, 2017

Tide-wrack; October collection

Each stretch of shore, and each season, even each weather pattern, has its own assortment of toss-ups. Towards the end of October, after several days of wind and wild waves, the northern section of Oyster Bay had refreshed its collection, substituting kelps for the usual eelgrass fragments and sea lettuce salad.

Possibly a broad-rib kelp, Pleurophycus gardneri

The various kelps look as if they should be easy to identify by asking a few questions: do they have a stipe, and what's it like? Are they smooth, winged, frilled, or blistered? What is the holdfast like? Do they carry floats?

Once they land up on the beach, in fragments, they become confusing.

Blistered, with a stipe-like centre. Similar to seersucker kelp, but missing the 5 ribs.

Nice holdfast, with two stipes, one bearing a blistered and ribbed blade, one with a smooth blade.

Alien invader

I took the photo of that mess with the frog (I think that's what it's supposed to be), because I was annoyed at the intrusion. I carried the critter out, dumped it in the garbage. One less bit of plastic left on the beach.

But before I deleted the photo, I blew it up and looked at it closely, wondering what else was there in that hodge-podge of land-based and wave-tossed vegetation. See the little fly on the blade of kelp just above the neat, round leaf?

But there's more: I noticed first one, then another and another ... transparent segmented tubes, small and smaller, scattered here and there. I chopped them out of the larger photo:


What are they? Plant stems? Leftover worm tubes? Plastic trash? Now I'll have to go back and look for more.

Clamshell. At least this is easy to identify.

A small branch, riddled with shipworm tunnels.

The shipworm (Teredinidae) is a clam, disguised as a worm. It has a long, worm-like body, up to about a metre long, depending on the species. But it wears two hard, ridged clam shells on its head, and uses them to carve out its burrow in the wood, lining some of the burrows with a calcareous coating.

When shipworms bore into submerged wood, bacteria ... digest the cellulose exposed in the fine particles created by the excavation. (Wikipedia)

This one was a larger, fatter clam than most I see on these beaches, and the wood is fresh, (most Teredos eat rotting wood), exposing the beautiful grain of the wood. (Click to look at it full-size.)

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