[Tweeters] Birds and Bivalves

Jeff Gibson gibsondesign at msn.com
Tue Sep 2 19:38:10 PDT 2014








I'm back in Mudville (AKA Everett), and also back on the "boat job from hell" - sanding a boat parked in a boathouse at the Everett marina.
One of the side benefits of the job is being down on the water and seeing interesting sea life. Last time I was here the entertainment was largely various fish. A lot fewer fish around this week - a sea change, I guess. But there's always something going on, and lacking fish, mostly, I turned to Barnacle, and Mussel watching. "Whoa, how exciting!" you may not be thinking. However these animals are interesting, I think, and so do many birds.
I wrote a post about barnacles a while back because I enjoy barnacle watching, and the watching is pretty good now on the floats and pilings of the boathouse : when looking down a piling at high tide, the barnacle colonies are shimmering with the movements of feathery barnacle feet. Pretty cool, really. If that's too much excitement for you, try Mussel watching.
Now Mussel watching isn't for just any idiot - it takes a certain set of skills, patience being one. Why? Because Mussels are apparently doing nothing under water except just sitting there - or so it looks like to most folks. Actually, Mussels are quite busy, breathing and eating. If you watch a Mussel long enough, you might have some sort of epiphany ,or something like one. Watch closely.
Mussels, and Clams, are bivalves, are filter feeders, and are pretty talented. For one thing, they practice circular breathing - drawing water in one siphon, and through their gills for oxygen - then blowing the water out another siphon, in a continuous flow. Some hominids have used circular breathing for a meditation, and some for music (or both at once) - Australian aborigines use it when playing those didgeridoo's , and other folks use it to get extra long notes out of their various wind instruments. You might wanna try it yourself.
These bivalves are also accomplished multi-taskers - they eat and breathe at the same time - the water they draw through their gills for oxygen, is also full of the tiny planktonic stuff they eat, which is filtered through the gills and to the stomach. This is one skill you might leave to the bivalves - if you try breathing at home while ingesting food, you might wind up blowing milk out of your nose, or get food down the wrong tube, or whatever.
Yup, bivalves are talented and entertaining - I could go on. Everybody thinks that the brainy Octopus is the best Mollusk, but I say, give bivalves a chance - check 'em out. Many birds are.
Of course birds are interested in bivalves for food, and so am I. There are a number of strategies that birds use to eat those bivalves; Oystercatcher's and Turnstones eat mussels by prying open the shells with their beaks; Surfbirds eat mussels shell and all, apparently, as do a number of diving ducks, such as Harlequins, Scoters, etc. ( having watched Barrows Goldeneyes eat mussels off of dock floats in Everett in the winter, and Surf Scoters hork down big ones , I can only imagine their "gizzards of iron").
And then, there is the well known "operation bivalve drop" as performed by Gulls and Crows dropping clams on a hard place to break them open. I read a great excerpt from the book "Gifts of the Crow", by John Marzluff, and Tony Angell , about Crows learning new ways to break open clams at a Washington State Ferry dock. At the ferry, the Crows gathered clams from the nearby beach , dropped them on the empty offloading lane of the ferry dock, and then flew back to get more, and dropped those too. The Crows waited until the offloading ferry traffic from the next boat had crushed all the clams, and only then came back to eat all the cracked clams - after the offloading was done , and the lane now free of traffic.
Jeff Gibsonmollusk watcherEverett Wa










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