Two jellies

It's that time of year again. The jellyfish are washing ashore.

Lion's mane jelly, Cyanea capillata. Floating in a bed of shredded sea lettuce with browned eelgrass garnish.

The bell of the lion's mane jellyfish is scalloped into eight lobes (lappets), each lobe containing from 70 to 150 tentacles, arranged in four fairly distinct rows. Along the bell margin is a balance organ at each of the eight indentations between the lobes – the rhopalium – which helps the jellyfish orient itself. From the central mouth extend broad frilly oral arms with many stinging cells. Closer to its mouth, its total number of tentacles is around 1200. (Wikipedia)

The rhopalia are located in those orange Vs between the lobes. This year, the Vs were strongly marked in all the lion's manes that washed up at Oyster Bay; I looked back through older photos of the jellies, and they were either the same colour as the rest of the jelly, or just slightly yellower.

By the time the dying jelly reaches the shore, most of the tentacles have disappeared, and the edges are fraying.

Moon jelly, Aurelia labiata, with sea lettuce, rockweed, sea cauliflower, and eelgrass.

Moon jellies

At the marina, one afternoon last week, the currents had brought in a swarm of moon jellies. I discovered one in the deep shade between a boat and the dock.

Aurelia labiata. Large male, about 5 inches across.

Out in the open, the jellies are foggy blobs with pale pink horseshoes at the centre. In the dark, even the radial canals that transport liquids through the body are visible.

The pink circles are the gonads; the frilly stuff below (above in this photo, as the jelly turned upside-down for a moment) are the oral arms, that catch the jelly's food and move it up to the mouth in the centre. The stinging tentacles on this jelly are confined to a short fringe around the rim of the bell.

Right side up.

Everything is in multiples of four; four gonads, four oral arms, eight lobes, each divided into two, making 16 scallops along the outer fringe. At the outer corners of each lobe, sensory organs, rhopalia, are just visible in this photo. Each rhopalia contains eyespots, sensitive to light, and statocysts, which alert the jelly when he's off-kilter. (There's a good photo of the rhopalia on E-Fauna, here.)

Moon jelly as seen out of the shade.

GPS: 50.035183, -125.244761