The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note any observations you have made of the world around you. Rain, sun, wind...insects, birds, flowers...meteorites, rocks...seasonal changes...all are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located. Each note is a record that we can refer to in the future as we try to understand the patterns that are quietly unwinding around us.
March 2, 2015
Salish Sea, Pacific Northwest
Spring has arrived in many parts of the country, as we've been sharing lately in the Bucket (though some folks are still waiting. Sorry! your time will come soon :)). In the Pacific Northwest one welcome sign of spring has nothing to do with warmth or flowers or the birds and the bees. It is seeing the beaches again, with our lowest tides now during daylight hours. Finally! In winter the water laps high against the driftwood during our short days. It's possible to explore the intertidal zone at night in winter when the water is way out, but I'm getting too rickety to risk tripping over rocks, slipping on seaweed or getting boots stuck in mud in the dark holding a flashlight in my teeth.
The other day I did some exploring at this muddy/sandy beach which at first glance looks pretty quiet and empty of life. Not so!
On a beach like this, if you're not a burrower, the most valuable real estate is hard surfaces, to attach to. That would make the derelict boat and the boulders magnets for life...but there's not much visible. Where are the critters? Yes, they've been hiding out under rocks, protected from wave action during high tide and dehydration when the water drops 8 feet vertically leaving the beach dry for hours.
So let's take a peek around and under some rocks and see who's here this spring - being careful to replace the boulders gently just as they were! That's their home.
Some animals are permanently affixed to the rock on an exposed surface, like this Purple Sponge and Acorn Barnacles, both filter-feeders, who wait for food washing past them in the current. If their boulder should roll over in rough seas pressing them against the mud they would go hungry unless they got lucky in another big storm.
Others are mobile to some degree. Under this rock the colorful garlands are the soft sticky tubes of Terebellid worms, decorated with bits of shells. The worms are detritivores, emerging partly from their tubes, sweeping tentacles across surfaces for bits of dead organic material. Sharing the underside of this boulder we find several kinds of mollusks: cone-shaped limpets, furry edged chitons, and various snails. The limpets and chitons rest during the day. Come nightfall they venture out to scrape algae and tiny hydroids off nearby rocks, and then each returns to this same spot to wait out the day.
I see a barnacle glued to the top of one chiton. Its fate is permanently linked to the chiton's, for better or worse.
(All photos by me. In Lightbox...click to enlarge)
Lots of other species of worms live under the rocks besides the various Terebellids, and some can move pretty fast, like the several here. The free-living worms are predatory carnivores.
There's actually space under the boulders as water washes through and rearranges the sediment underneath, creating a curved muddy pool. Plenty of room for small animals who stay wet there for the hours the tide is out.
This rock had a group of whelks piled amidst yellow eggs probably laid by other whelks since these look old and gnawed on. It wouldn't have been the green armadillo-shaped isopod cruising over the whelks since it's a herbivore, looking for seaweed.
A welcome discovery under this rock is a baby seastar - see it? After the massive epidemic last year that decimated seastars all along the west coast, this sighting could be a sign of a population recovery. This species is the 6-legged Seastar.
Some creatures under rocks are quicker than I am. A hermit crab darts away so fast its legs are a blur. From the photo I can tell it's a bit too big for its whelk shell home. This crab will be looking for a bigger shell soon.
Tiny Purple Shore crabs usually scuttle away as soon as I lift a rock. This one paused a moment, revealing its purple spots. Shore crabs are scavenging omnivores, and whelk eggs are a seasonal treat.
Enough water pools in the crevices under boulders to support even fish! Gunnels are common but will quickly slither out of sight. These fish can breathe air and safely snap up worms and crustaceans while the beach around them is dry.
Safely, meaning temporarily out of the reach of their aquatic predators: otters, diving birds and other fish. The boulders provide protection for all these creatures not just from dehydration and waves but also from animals hunting for prey in the shallow water of the bay and on the beach. The many empty shells on the beach attest to the marginal nature of that refuge. Birds along the beach are experts in reaching into crevices, like this gull.
There were lots of other critters under the rocks this day, and some I hoped to see but didn't (like a brittle star). Now the season is turning toward spring and summer I'll have many more chances to revisit the life hiding under rocks.
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The Bucket is open for your reports of what's happening in nature in your part of the country. Spring or winter? Wildlife you haven't seen in a while?
"Spotlight on Green News & Views" is posted every Saturday at 1:00 pm Pacific Time and Wednesday at 3:30 on the Daily Kos front page. It's a great way to catch up on diaries you might have missed. Be sure to recommend and comment in the diary.