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Dive Dry with Dr. Bill

#530: Not All "Jellies" Sting

Over the past month or so our local waters have seen an influx of transparent to translucent jelly-like critters. I filmed several from Cabrillo Mole a month ago and while down at the dive park last weekend counted seven jellies right near the stairs. The next day I descended and filmed at least 13 of them before running low on air. Now the politically correct crowd prefers to call these critters sea jellies rather than jellyfish. They believe you and I are so stupid we think they might actually be a fish. You're not, are you? Of course not... only intelligent people read my column. Not so sure about the guy who writes them though.

Now I contend that "sea jellies" is an even worse misnomer than "jellyfish." Observant boaters, divers and beach combers have wisely noted that there have been a number of jelly-like critters offshore and on our beaches, not just the stinging kind formerly known as Prince... er, jellyfish. I have seen salps, ctenophores and even snails in the water column as well. None of these will sting you. In fact salps, or pelagic tunicates, are our closest relative in the invertebrate world since their larvae actually have a nerve chord. They are just about as far away on the evolutionary spectrum from jellyfish as you are from an earthworm!

Prior to diving to film the jellyfish, I presumed they were fried egg or egg yolk jellies (Phacellophora camtschatica). When healthy and reproductive, they look like a fried egg because the whitish bell of the jellyfish has orange gonads embedded around its center that look like a yolk. These individuals were dying and in very tattered shape, the result of a number of fish including kelp bass and garibaldi that munched away their tentacles for a spicy snack. Unfortunately that also made a positive identification difficult (I'm no expert on Cnidarians) since one key to knowing for sure is counting the 16 lobes that carry the tentacles. The "oral arms" that dangle below their "mouth" are complex and folded, and this helped me decide on the species.

The fried egg jellyfish is often seen in our waters, at least at certain times of the year. The recent invasion involved a lot more than I usually see close to shore. These sea jellies are known from Chile to Kamchatka, Alaska, and across the North Pacific to Japan. They may be found in other areas as well since they are planktonic and mostly drift with the currents. This species may reach a diameter of about two feet although most of the ones I've been seeing were about half that. Fortunately their sting is pretty mild so I knew I could get up close and personal without risking major discomfort. If intact, the tentacles may extend to 20 feet or more. One that I filmed had tentacles about 15 ft long, but on most they were missing. They use them to capture and feed on other sea jellies.

Now I prefer my fried eggs a bit scrambled as I'm not too fond of yolks. But you are probably wondering why the "yolks" weren't present in these specimens. I'm making a scientific guess here, but I think the reason relates to their imminent death. Frequently when an animal is in stress, such as occurs during the process of dying, it may also suffer from malnutrition. Obviously jellyfish which lack tentacles are not going to be very successful in capturing prey (or defending against predators). When food is not being obtained, non-essential organs may be reabsorbed to provide nutrients for survival. I'm guessing that these jellies may have "fed" on the orange gonads to sustain life. That's why I make sure to eat seven healthy meals a day!

But I mentioned that jellyfish are not the only sea jellies seen in our waters recently. Other gelatinous critters observed included ctenophores, known more commonly as comb jellies. Some seen here in the past few weeks included Leucothea pulchra, Beroe forskalli and the Venus' girdle (Cestum veneris). Sorry about the scientific names, but many critters in the sea just don't have common names. These invertebrates have rows of cilia (called combs) that beat to propel them through the water. The cilia refract light and make the comb jellies look almost as if they are lit up. Some feed on crustaceans, while others are cannibals munching on other comb jellies.

The salps have included Cyclosalpa affinis and Thetys vagina. I've written about both these species previously so check my web site. Most salps filter food out of the water column as they drift along. Internal organs may be quite obvious through the transparent to translucent bodies. They are more complex than a jellyfish but less advanced than a salp.

Finally another group of gelatinous goop has been seen in our waters. These are the heteropods... a group of snails with greatly reduced shells that live in the pelagic or open water zone. Rather than crawl slowly along the bottom like their shelled relatives, they too drift with the current as plankton. One species is the sea butterfly, Corolla calceola. Although more common north of Pt. Conception, they do enter SoCal. It has what appear to be oval wings which give it its common name. To feed they form a mucus sheet about six feet in diameter to capture planktonic food. Another species, Carinaria cristata, munches on salps as well as small crustaceans.

Years ago I used to do what we call blue water dives. We would head out in a boat several miles offshore (sometimes halfway to that "big island" across the water) and drift below the boat to film these "jellies" and other planktonic critters (not to mention a few curious sharks). One had to be pretty careful on these dives. If I dropped my camera, it could fall a few thousand feet to the bottom and I'd never retrieve it. So you see, not all "sea jellies" are jellyfish. Blue water diving is becoming quite popular these days. There's a fascinating world out there in the open ocean.

© 2013 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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Living fried egg jellyfish and one in "terminal phase;" the comb jelly Leucothea and the salp Cyclosalpa.

This document maintained by Dr. Bill Bushing.
Material and images © 2013 Star Thrower Educational Multimedia