561 words • 3~4 min read

#TaxonomyFail: Salps, Jellyfish, and the Diablo Canyon Nuclear Power Plant

I’m a bit late to the party, but last week, several news outlets reported that the Diablo Canyon Nuclear Power Plant was taken offline by “jellyfish-like creatures” that clogged several cooling intakes. While most sources were careful to point out that these were “jellyfish-like” organisms, some secondary sources truncated the description and announced that “Nuclear Power Plant Knocked Offline By Tiny Jellyfish, The Invasion Has Begun”. Unfortunately, these organisms are salps, not jellyfish, and you’d be more correct to describe them as human-like rather than jellyfish-like.

Salps, photo by Lars Plougmann

Salps, photo by Lars Plougmann

Salps are free-swimming pelagic tunicates, one of the most basal members of the chordate phylum. While they superficially resemble jellies to the untrained eye, they are far more derived, possessing three tissue layers (compared to the jelly’s two), a primitive, larval notochord, a perforated pharynx, and the rudimentary beginnings of a centralized nervous system. They form large, clonal colonies that are able to take advantage of plankton blooms by rapidly producing more clones to capitalize on an unpredicatable food source. Although I don’t have first hand reports, this is likely what happened in Diablo Canyon, as warm water discharges from nuclear power plants can trigger massive plankton blooms. Far from a “jellyfish invasion”, this was probably the natural response of a predator to increased food availability.

There’s been quite a few taxonomy fails in the news recently, from carcass monsters to frapachino beetles. Several years ago, Alex Wild of Myrmecos proposed the “Taxonomy Fail Index” a measure of how bad a species identification is “scaled by the amount of error in absolute time against the error of misidentifying a human with a chimp“. Describing a person as a bonobo would be a TFI of 1. Wild’s example of a possum misidentified as a cat pulls in a TFI of 24.6.

So what about misidentifying salps as jellyfish? TimeTree is a pretty good resource for calculating divergence time between species, and yields 891.8 million years for a representative salp genus and a representative cnidarian genus. Other sources confirm this estimate and put the divergence time at between 800 and 900 million years ago. At 891.8 MYA over the 6.4 MYA used to scale to a human/chimp identification, our jellyFAIL has a whopping TFI of 139.3!

So here’s my challenge to our readers: find me a mainstream media taxonomy fail in domain Eukaryota with a TFI higher than 139.3. The winner will receive a copy of “The NEW SCIENCE of SKIN and SCUBA DIVING” a 1960′s era SCUBA manual full of hilarious historical anecdotes and illustrations. Happy hunting!


Deep-sea biologist, population/conservation geneticist, backyard farm advocate. The deep sea is Earth's last great wilderness.


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