Dive Dry with Dr. Bill

049: Sunny-side Up or Over Easy?

I rarely eat fried foods these days although as a high school swimmer I always cooked fried eggs for breakfast to go with my sausage and cereal (and Wheaties, of course... the breakfast of champions). Back then I could easily burn off 4,-6,000 calories. Today the closest I've come to one was a few weekends ago when a very large fried egg appeared above me while diving... a fried egg jellyfish.

Of course jellyfish are not fish any more than starfish are. They are cnidarians related to corals and sea anemones. This species is not common in our waters, but recently there have been several sightings off Catalina and a number of them were seen in the San Diego area in 1990 and again this year as well. They have a scattered distribution world-wide and are found from Chile to Alaska and Japan in the Pacific Ocean. Normally they are a pelagic species, drifting in the open ocean. In fact despite their size (up to 24" across), they are considered plankton due to their limited ability to swim against prevailing currents.

The bell of this jellyfish has 16 clusters of up to 25 tentacles each which may be 10-20 feet long. As it pulses through the water, these undulating clusters create a image of grace and beauty. Like its relatives, the tentacles have stinging cells known as nematocysts. These cells release little harpoon-like stingers attached by a thin cord. When the stingers strike potential food, they can hold it until the tentacles bring it to the central mouth on the underside.

I wanted to get up close and personal to take some good video of the tentacles and in the process the tentacles got some good shots at me! However the stings were very mild compared to my expectations. I watched one tentacle, torn loose by the rocks on shore, drift close to a kelp bass which eyed it, then swallowed it with no apparent negative effects. I guess it liked its food a little on the "spicy" side!

The yellow "yolk" of this jellyfish is actually the reproductive structures or gonads. Given their large mass in the specimen I observed, it may have been in reproductive mode. When the adult jellyfish releases its gametes, they fertilize and become larval forms known as planulae. The bell and other body parts are clear to white or pale yellow.

So what does an open water jellyfish with only a mild sting feed on? Hard to imagine they could catch fish given the kelp bass' response to its sting. In fact small fish are occasionally seen swimming among its tentacles. Apparently they feed on other jelly-like plankton including jellyfish. Now when you consider that most jellies are 95% water, that doesn't sound like a substantial diet unless you're looking to lose a lot of weight! Hmmm, perhaps I should try it.

The fried egg jellyfish is actually a tiny "ecosystem" itself. Symbiotic amphipods and juvenile crabs often live on its body. However, I did not observe any of these on this jellyfish. I kept shooting this beautiful creature until the surge sucked it into a hole between the rocks of the breakwater. When it briefly emerged, it was a bit tattered from the experience. Before I could get more than a few seconds of additional footage, it was sucked back into the hole and didn't re-appear. I guess its back to coffee and a banana for breakfast now.

© 2003 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Image caption: The fried egg jellyfish as it pulsed through shallow water
along the breakwater in the Casino Dive Park

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia