The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note of 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.
December 2013
Olympic National Park
Pacific Ocean Washington state coast
(All photos taken by me. In Lightbox, click for a larger view)
My inland waters of the Salish Sea have several kinds of anemones - white, brown, tan, pink, even striped - but the Great Green Anemones are rare, found only in places of high surf, rare and mostly inaccessible habitat in these quiet straits and bays. The Great Greens are also intolerant of pollution, limiting their distribution in developed areas.
So a trip out to the wild open coast, with big waves and unpopulated rocky coves, gives me a chance to find these gorgeous big anemones. Last week I went in search of Anthopleura xanthogrammica, the Great Green Anemone, that luminous creature you see above, along the shores of the Olympic peninsula.
The Great Green prefers to be covered by the sea most of the time. I went looking at low tide, first among the carved rocky headland north of Rialto Beach. The shoreline looks like this. Even at low tide you can see the surf rolling in, creating narrow channels where the anemones settle themselves, waiting for food to wash in.
This Great Green is sharing a tidepool with two kinds of coralline red algae. The green color of this anemone is a pigment generated by the anemone which acts to protect it from UV light. The Great Green also contain symbiotic green algae, zoochlorellae, which act much as the endosymbionts of corals do (anemones and corals are related, both are carnivorous animals with stinging tentacles). Warm water and pollution drive the endosymbionts from corals, a process known as bleaching; anemones are less susceptible and don't bleach as readily.
Follow me below the curly tentacles for more Great Greens...
A few miles south of there, the rocks are spaced more, creating nooks and tidepools, surrounded by sand, good Great Green habitat.
Where the Great Greens are more shaded by the rocks, they glow less brilliantly green in their deep pools, mostly high and dry right now at low tide.
Anemones close up their tentacles when the tide drops, partly because there's no need to be in feeding mode, but also as protection from dessication. The Great Greens attach a covering of small rocks and shells to their outer surface too.
Predators of the Great Green include some snails and nudibranchs, and the Leather Seastar. These Ochre Seastars are ignoring the anemones, in search of mussels and barnacles higher on this rock.
So what do these sedentary carnivorous creatures eat out here, and why do they need big surf action?
Their primary food is mussels (a bivalve mollusk) which are well attached to their rock substrate by strong threads.
Clumps of mussels are ripped from rocks by big waves, like the clump above. The Great Green snags a passing clump, pull it inside and digest the soft parts, ejecting the empty shells.
There's a special spot I like to climb out to on a headland near Second Beach, only accessible at a very low tide. It has a broad terrace of nothing but mussels, facing the oncoming waves which break directly on it.
There's a spot just behind the terrace I can safely avoid getting hit by the waves, mostly spent by intervening rock formations. It is exciting and dramatic to watch that surf rolling in, colliding with the rock. I can feel the booming right through my feet. The waves swirl around into a channel next to me.
Sharing my spot behind the mussely rock terrace are crevices filled with Great Green anemones, just waiting for a wave to pour over the top carrying yummy mussels. I was taking some photos of these anemones and turned my back on the surf just for a moment, when a sneaker wave blew around the corner, higher than any other during the time I'd been standing there. Split second decision: try to climb to higher ground or stand fast? I chose to stay put, holding on tight. It was ok. I got wet only to my knees. It was a squelchy walk back along the trail, but what fun to be in that dynamic oceanic element!
So this is a little of What I Did On My Holiday Trip to The Ocean. Thanks for coming along in this diary.
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