Mee-Kwa-Mooks Beach 5/6/12

Coordinates: Lat. 47.56465
Lon. -122.40846
Weather: 65 degrees F and fully sunny! But just as last time, strong winds keep us chilled.

10am-- The tide is receding as we move along the beach. Low-tide is at 11:30am and should be especially low today as a result of the supermoon. The beach, as described in my previous entry about Mee-Kwa-Mooks is completely rocky. The upper 20-30m of beach are fairly dry--likely that they haven't been underwater in a while. But just beneath this dry strip, where rocks are dispersed over sand, you immediately find a plethora of aggregating anemone (Anthopleura elegantissima). These anemone are not attached to tocks, but rather are rooted in the sand. Often times they are found in clumps of 15 or more all in a close circle about 1ft x1ft. Each anemone is about 4-5 cm across and completely sucked in- the tentacles are not visible. Curiously, however, all of the anemone in the upper section of the beach are covered in small bits of white shell. The shell is piled onto the green anemone, but is not necessarily scattered about on the area surrounding the anemone body. In other words, it looks deliberately piled onto the creature. I imagine that the shell protects the anemone-- it certainly looks like a kind of armor. The brilliant white might help to repel UV rays from the sun, as well as camouflage the anemone from predators. The anemone closer to the water do not have this shell protectant. They spend less time exposed to the sun and predators than the anemone that live higher up the beach, so perhaps they simply have not adapted such a mechanism. The anemone form close circles as a result of their aggregating nature-- they reproduce asexually by cloning. Often, when you see hundreds of anemone clumped or spread across a beach, they are really just clones of a single anemone.
The large abandoned tire that creates a little tide pool has a tidepool sculpin today! (Oligocottus maculosus). It sits perfectly still on a barnacled rock, probably barely 6cm deep in the water. The water feels warm to the touch under the hot sun. I wonder how well this tiny creature does with swift temperature changes? Does it change an animal's metabolism?
Walking down the beach I discover a very small pool of water (one of a million) that contains a floppy, shaggy creature: a nudibranch! It is somewhat rare (or at least special) that you discover a nudibranch on the beach, especially not one as large as this! This nudibranch was about 11cm long when fully extended, but could squish it body into a small ball when not moving. Its mauve coloring and flattened cerata give it the appearance of a shag rug: therein earning its name Shaggy Mouse nudibranch (Aeolidia papillosa). The color of the nudibranch is effected by the food it has been eating- fluctuating from pink to orange to grey or white. Nudibranchs feed primarily on sea anemones--often of a singular species due to their limited mobility.
Later, we find another tiny nudibranch among the eel grass, this one only about 2 cm long, with translucent blue, shimmery tentacles at its front. Its shimmer distinguishes this sea slug as an opalescent sea slug (Hermissenda crassicornis).
Other highlights were finding many sun flower sea stars, and a Troschel's sea star at the lowest part of the beach, just before the tide turned.

Species List:
Ochre Sea Star (Pisaster ochraceus)
Sunflower Sea Star (Pynopodia helianthoides)
Troschel's Sea Star (Evasterias troschellii)

Shaggy Mouse nudibranch (Aeolidia papillosa)
Opalescent nudibranch (Hermissenda crassicornis)

Aggregating anemone (Anthopleura elegantissima)

Tide pool sculpin (Oligocottus maculosus)

Publicado por jesscubb jesscubb, 01 de junio de 2012

Observaciones

Fotos / Sonidos

Observ.

jesscubb

Fecha

Mayo 6, 2012

Descripción

We found this little nudibranch (sea slug) when we scooped water into a tray from a bed of eel grass. Here it is pictured on top of a sand collar. The body was only about 2 cm long. I am guessing it was a young nudibranch, but I don't think that this species grows all that much larger.

Fotos / Sonidos

Observ.

jesscubb

Fecha

Mayo 6, 2012

Descripción

Troschel's Sea Star is not unlike the Ochre or Purple sea star except in that it's limbs are considerably slimmer and the central disk much smaller. This one was exposed on a rock at low tide, but at the very lowest portion of the inter-tidal zone, only about 1m from the water at the tide's lowest point.

Fotos / Sonidos

Qué

Anémona Elegante (Anthopleura elegantissima)

Observ.

jesscubb

Fecha

Mayo 6, 2012

Descripción

These small anemone (3-5cm across) completely cover the sandy areas of Mee Kwa Mooks. The two pictures included depict anemones from farther up the beach (furthest from the water) and others nearer the water. The anemone higher up on the beach are consistently covered in bits of shell, while the ones closer to the water are quite exposed. It seems that the bits of shell must be an adaptation to the greater exposure high up the shore- more time under the sun and in the open air. The bits of brilliant white hell would efficiently deflect UV rays from the delicate anemone. I am guessing that these are aggregating anemones, which means that they are clones of each other.

Fotos / Sonidos

Qué

Charrasco de Piscina de Marea (Oligocottus maculosus)

Observ.

jesscubb

Fecha

Mayo 6, 2012

Descripción

Though it seems pretty clear that this is a sculpin, I am unclear as to the species. I only guess tidepool because it was discovered in a tide pool! A huge tire left on the beach has filled with water and now acts as a tide pool full of creatures. This fish was about 9cm long, seemingly resting on the stone in the tide pool.

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