Friday, September 09, 2011

Tangled jelly

The tide was at its peak in Boundary Bay and had brought in a number of lion's mane jellyfish. They lay, drying and shrinking, on the roll of brown eelgrass, or disintegrated as the waves scraped them across rocks.

We found one a few feet away from the shore, apparently still alive, floating in about 6 inches of water. And I had the underwater camera with me; I held it down on the rocks to get a view of the underside of the jelly.

Lion's Mane, Cyanea capillata,  mirrored on the undersurface of the water. The upper and lower skins of the "umbrella" are visible.

The tangled mass is made up of the four oral arms (mouthparts). The stinging tentacles are thin and silvery; I barely see a hint of them here.

Top view. 

The lion's mane has eight lobes, clearly marked in this one by the pinkish Vs at the inner curves and the tips of rays at the widest points. Each of those Vs is a rhopalium:
The rhpoalia (singular rhopalium) are the small pink structures, 8 in number in our model, which can be seen located around the bell margin at regular intervals, between lappets. These are sensors. Each rhopalium contains a gravity sensor, which allows the jellyfish to tell which way is up and which way down, and to know how much its body is tilted. These organs may also contain what look like olfactory (smell) sensors and in some species each rhopalium has a tiny eye. These eyes may be simple light sensors, or they may be complex eyes equipped with a lens. Some jellyfish do not have eyes, but even these can detect light by other means. (From
Around the center mouth is a crown-like rim. Just outside that, if you look closely (or click on the photo to see it full-size), you can see the rings of muscles that close and open the bell.

1 comment:

  1. Great shots. I've only seen them washed up on shore. - Margy


If your comment is on a post older than a week, it will be held for moderation. Sorry about that, but spammers seem to love old posts!

Also, I have word verification on, because I found out that not only do I get spam without it, but it gets passed on to anyone commenting in that thread. Not cool!