Dive Dry with Dr. Bill

#245: Jellies... Without The Sting

Back in the 1950's when my family lived on the beach in northern Florida (well, actually in a home near the beach), my mother was stung by the notorious Portuguese man-of-war. While not a true jellyfish, this siphonophore is often linked with them. I've had a healthy respect of soft translucent "thingies" that can sting ever since. The only jelly I really love is the jelly belly (yum). Fortunately most of our local jellyfish don't have the zing or toxicity of the man-of-war... I know, I've been stung by several while trying to get up close and personal when filming them.

In early August the King Neptune anchored at Blue Car Wreck below Avalon's dump, and our divers entered the water. I had informed them of all the "turtle eggs" on the bottom there... you know, the ones with dimples and names like Titleist, Spaulding and Wilson. As I submerged, I immediately encountered the highlight of my dive. There were dozens, if not a few hundred, translucent "jellies" drifting and pulsing in the water. However, these "jellies" carry no sting. They were "comb jellies," known scientifically as ctenophores.

Ctenophores are somewhat unique in the invertebrate world, and are members of their own phylum or group. They have eight rows of ciliated plates called ctenes, and are the largest critters to use cilia for locomotion.... come on baby, do the locomotion with me (shades of Little Eva in 1962, or Grand Funk Railroad in 1974 for those of us old enough to remember). The ciliated "combs," stacked up on one another, actually look like a series of the combs favored by our lovely Latin women to hold their hair in place. When they beat, beautiful rainbow colored patterns are created through irridescence, light diffracted by the closely-spaced combs similar to the effect of a prism on sunlight. This effect is not like the bioluminescence you see in our waters at night... or when you flush your salt water toilet (the "green flush") without the lights on. However, some ctenophores can also bioluminesce.

Some ctenophores live a planktonic life in the upper water column and may enter coastal waters, but many are denizens of the deep ocean... much deeper than Dr. Bill will dive to! Although they are jelly-like and active carnivores , they are not closely related to our stinging jellies in the phylum Cnidaria. They lack the nematocysts that can make a close encounter with that group one of the "worst kind." Many comb jelly species feed on animal plankton, and some will prey on other comb jellies. Their transparency is their primary defense against visual predators like fish and turtles, but does them no good against other enemies like true jelly "fish" which do not feed by sight.

Ctenophores have a structure known as a statocyst which has a tiny calcareous particle in contact with ciliated nerve cells. It allows these brainless critters to sense their position in the water column and adjust their orientation. They can even change their buoyancy without the need for a BCD! Of course we used to do that when diving "vintage" equipment back in the 1960's!

This column would be incomplete, and my readers disappointed, if I didn't at least touch on the sex life of ctenophores! Most species have both male and female organs and are simultaneous hermaphrodites. A few species have separate genders. Although they release sperm and eggs into the water where they fertilize and develop into drifting larvae, some are capable of self-fertilization (now what fun is that?).

I observed at least two species on this dive, neither with a common name. The most abundant was Leucothea pulchra which may reach 10" in length and has distinctive brownish-orange papillae making identification easy. They have lobes on either side of the mouth that are folded together into a tube to slurp up copepods and other plankton. The other, Beroe forskalii, is shaped like a flattened ice cream cone with one end broad and the other pointed. It hunts in a spiral pattern and engulfs its food, which includes smaller Leucotheas, in its huge mouth. When food is abundant, and they have eaten more than their share, they can appear to swell up like a big balloon. I resemble that at times.

While filming these two species, I noted they served as home or habitat for a few other, unrelated species. I saw a skeleton shrimp or caprellid amphipod attached to one Leucothea. It appeared to jump off the comb jelly and snatch food out of the nearby water column, although I think they may also feed on some of the host's tissue. Two others had fish larvae living on their surfaces. The larvae also darted off to snatch food, but quickly returned. One was uniquely shaped like a triangle. Unfortunately even my high definition video (HDV) camcorder couldn't capture enough detail to identify them.

Since many of these comb jellies were in the upper twenty feet of the water column, I could film them without the need for my now-departed video lights. Having them would have brought out the irridescence as their combs beat along the side of their body, but until I find a sponsor who can fund this educational endeavor properly... wishful thinking is all I can muster.

© 2007 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. Please help me climb out of self-imposed poverty... buy my "Munching and Mating in the Macrocystis," "Great White Sharks of Guadalupe," "Calimari Concupiscence: Mating Squid, " "Playful Pinnipeds: California Sea Lions," "Belize It or Not: Western Caribbean Invertebrates, Fish and Turtles," "Gentle Giants: Giant Sea Bass" or "Common Fish and Invertebrates of the Sea of Cortez" DVD's. Yes, take Dr. Bill home with you... we'll both be glad you did!

The comb jellies Leucothea pulchra (top) and Beroe forskalii (bottom).

This document maintained by Dr. Bill Bushing.
Material and images © 2007 Star Thrower Educational Multimedia