Drawn from the deepFebruary 17th, 2012 by Jeff Adams
OK, so we’re unlikely to witness the rise of a leviathan, but tomorrow evening (Saturday 2/18 from 7:30-8:30), you can join Kitsap Beach Naturalists, along with me and my WSU Kitsap Extension colleague Peg Tillery at the Bremerton Marina (map). We’re taking a break from the night time low tides to explore the subtidal and free-swimming life that can be enjoyed on almost any floating dock, at any time. Night time on a dock can bring even more sea life to the surface with the aid of a bright light.
You never know what might respond to lights pointed into the water at night. Ever watched squid jiggers at work – often in the cold, often in the wet, always in the dark? Their porcupine lures rise and sink through the water in or around a column of bright light. Schools of squid are attracted by the lights and often can’t help but embrace that brightly colored tube, entangling themselves in the lure’s spiny skirt. The jiggers are taking advantage of the many-armed tasty’s attraction to light.
What else will be attracted to the light? Many creatures spend the daylight hours below the photic zone – the top layer of the water where there’s enough light to support plant growth but also enough to be easily seen by predators. Every evening they come to the surface to feed under the safety of darkness, then return to the deep as the sun rises.
The spring blooms are yet to arrive but some small organisms and even some jellies still float around near the surface. Imagine you’re a tiny copepod (about as long as the thickness of a dime) and you’re happily filtering tiny particles out of the water. Leviathan being something of a matter of scale, the hairs near your cycloptic eye may rise in fear as dusk settles in and from below swims an torpedo-shaped arrow worm (Sagitta elegans). It’s 40 times your size (about the length of a football field compared to a tall human) with rows of hooked hunting spines on either side its head (ironically not unlike the squid jig). Yikes! … Back to your human self, just shake off your imagination and remember the arrow worm’s only an inch and a half or so long.
No guarantees on what we’ll see swimming in the water, but there’s always a spectacular show to take in on the submerged areas of the dock.
Most animals and plants on the docks don’t move through the open water and rely on the hard surfaces of the dock to give them a strong foothold that they would otherwise only find from rocks below the exchanging tide. Among these will be seaweeds, chitons, anemones, crabs, barnacles, stars, cucumbers, urchins, slugs and squirts… and (my personal favorite) the ugly clam.
Clams on a floating dock you may ask? This is no ordinary clam. In a natural environment, you’d find the ugly clam (Entodesma navicula) growing out of a crevice or between rocks, it’s shell deforming to fit its surroundings. It’s far easier to find these clams on docks where they are frequent inhabitants.
Another bivalve that lives on docks an form fits to its home is the false jingle shell (Pododesmus macroschisma). It’s bottom shell has a hole through which it attaches to it’s substrate. It also has bright orange lips that you can see while it’s feeding.
Speaking of lips, maybe we’ll be lucky enough to see a scallop or two flashing their bright smile.
Like the squid jiggers, it’s likely to be cold, wet, and dark, so bring flashlights or headlamps (something with a strap so it doesn’t fall in the water). Life jackets are a good idea for kids. Wear warm, waterproof clothes so you can even get down on belly if you like and get a closer look off the dock.
If you can’t join us tomorrow, go to the public docks nearest you any time they’re open. If you see something cool, let me know and even send a picture. I love that stuff and am happy to let you know more about what you found!
We’ll also be doing this again, so if you’d like to be kept in the loop, please contact me or Lisa Rillie 360-337-7157 x 3244 or firstname.lastname@example.org. Happy dock exploring!
Jeff Adams is a Washington Sea Grant Marine Water Quality Specialist, affiliated with the University of Washington’s College of the Environment, and based in Bremerton. You can follow his Sea Life blog, SalishSeaLife tweets, FaceBook and video posts, send email to email@example.com or call at 360-337-4619.