Friday, October 16, 2009

Water jelly, with food comparisons.

We got to the White Rock beach yesterday just at the top of the tide; a very high flood tide it was, too. The waves were soaking the black shreds of dried eelgrass at the rim of the intertidal zone. We were almost alone on the narrow strip of rocks, except for a flock or two of silent seagulls, waiting to follow the tide out in search of unwary clams and crabs. We walked for a long time.

On the way back, the water had receded a few inches and left a little pool in the muck. Something round and shiny caught my eye. Some sort of jellyfish.

It's completely transparent; the eelgrass underneath is all that gives it colour. Dragged out of the water, and laid out on a flat piece of driftwood, it looks like a semi-poached egg, about the right size, with a mounded "yolk" in the centre, yellowish because of the wood underneath.

Or, looking straight down on it, like a rubbery silicone gasket. The thick bell is so completely transparent that the wood grain is clear and detailed. There should be a mouth; it may be where there's a slight distortion in the upper right quadrant.

The radial canals are visible in the outer section; I counted 16 in a quarter of the circle. And there's a tangle of something else (muscle fibers? Nerves?) towards the inner edge.

I touched the top, gingerly, in case of stings. It felt like the finger Jello that I used to make for the kids, cool, firm, but with a nice "give" to it. I flipped the entire thing over; the underside looked just like the top. No stingers there, either.

View from the side: around the margin, looking at the photo full size, I can see tips of other structures, possibly tentacles.

I carried it out into the waves, and washed it off the board. It moved away quickly; it seemed to be contracting and expanding as it went. In the murky water, among swirling clouds of eelgrass dust, it looked like a whitish doughnut.

From the Encyclopedia, I gather that it is probably one of the water jellies, or many-ribbed medusas, Aequorea spp. They grow to about 7 inches across (Kozloff says the usual size is 7 cm., just under 3 inches.)


  1. Hi Wanderin'! I live on the east coast, and love marine ecology though I don't live right on the water. My knowledge of pacific ecology is limited, but I wonder if this jelly could be what we would call a "moon jelly"? I really enjoy your blog-mine is The Hill-Stead Nature Blog. Cheers, Diane Tucker, Estate Naturalist, Hill-Stead Museum, Farmington, CT

  2. Hi, Diane,

    The moon jelly is similar, but it has four coloured "horseshoe" marks in the bell. I saw no sign of these, neither on the beach, nor in any of my photos. The little fringes on the rim look right, though.

    The scalloped jellies are the other possibility, except that they are lobed, and I saw no lobes in my specimen.

    Thanks for the suggestion; it is appreciated.

  3. Neat critters. I flew in from Powell R., although I live in Muskoka, ON!
    Great shots.


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