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 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 plankt