Researchers have discovered that seemingly benign upside-down jellyfish utilize a unique, previously unrecognized weapon to capture prey: “Stinging mucus grenades.” It explains the “stinging water” pain that divers, snorkelers and waders sometimes experience without coming into actual contact with the jellies. Upside-down jellyfish have been recognized for some 200 years, but nobody knew this until now. TO ALL APPEARANCES, UPSIDE-DOWN JELLYFISH LIKE CASSIOPEA XAMACHANA spend their days resting on the shallow bottoms of reefs and
WHAT’S THE DIFFERENCE BETWEEN JELLYFISH AND COMB JELLIES? They both come in blobby shapes and gelatinous, transparent bodies. But comb jellies – ctenophores – are entirely different from their oceanic jellyfish neighbors. Most importantly: They don’t sting. And some of them put on fantastic light shows. Note that I said “neighbors,” not “cousins.” The difference between jellyfish and comb jellies runs far deeper than the absence of stinging. Recent research suggests that combs evolved with
LET’S TALK ABOUT HOW TO TREAT STINGS. My front page post, “Nematocysts and the Science of Sting,” discusses the way jellyfish, fire coral and other cnidarians bring about their painful stings. On dive boats, in dive shops and, of course, on the internet there are lots of theories about how to treat stings by cnidarians – most of it more urban legend than factual. Here are some facts, culled from medical resources. THINGS YOU SHOULDN’T
AT FIRST PASS, “CORALS EATING JELLYFISH” SOUNDS LIKE AN OXYMORON. But newly published research confirms that for at least one variety of stony corals, the concept of corals eating jellyfish is indeed a reality. Moreover, these tiny colonial animals appear to work together to capture and devour the much larger jellies. It’s the first described case of “protocooperation” among corals, say the authors of the article published in the journal Ecology. NORMALLY CARNIVORES, ANYWAY Coral polyps
TWO DENIZENS OF NOTE IN THE MANGROVE ENVIRONMENT are Cassiopea fronosa and Cassiopea xmanchana, both better known by the common name “Upside Down Jellyfish” (as we pseudo marine naturalist know, they should be called sea jellies but all the sources I.D. them as jellyfishes). NORMALLY ON THE BOTTOM Although they can swim, upside down jellies spend most of their time lying on their backs in shallow waters – mostly mangrove
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