This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
It has been widely noted that 2016 has been a remarkably crummy year. Let’s end the year on a better note with a creature of remarkable beauty that materialized in May during exploration by NOAA's Okeanos Explorer: a dandelion siphonpohore.
Grammar Police: It should be “Portuguese men o’ war”. Or perhaps Portuguese persons o’ war. Or best of all: Portuguese borg o’ war (see below). But no Portuguese man o’ wars. I’m guessing that white balloon in the center of the dandelion is a gas-filled buoyancy device, similar to the glassy bag that surmounts the Portuguese man o’ war.
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According to NOAA, dandelion siphonophores are usually found attached to the sea floor, so seeing one actively swimming does seem to be an unusual.
Nautilus Live – the ocean expedition sponsored by Bob Ballard -- had its own encounter with some less comely but still dandelion-like siphophores (“siphonofriend!”) off the coast of California this summer, but these had their anchor cables intact.
Those wet-spaghetti-looking tethers do not seem like they should be able to hold the animal in place, but perhaps they have something in common with spider silk.
All of these siphonophores are notable because, being compact and semi-stationary, they are quite unlike the lengthy drifting siphonphores you may be more familiar with (and Nautilus Live saw one of those this year too).
Just what is a siphonophore? Relatives of jellyfish and coral, siphonophores are both one animal and a colony of animals. A siphonophore starts life as a single embryo like the rest of us, but that embryo clones itself into dozens, hundreds, or thousands of conjoined twins, according to scientist and blogger Casey Dunn. The animals are budded – sometimes continuously -- from one or more pluripotent zones whose tissues can form any cell type (in animals, such substances are called “stem cells”, while in plants, they would be called “meristems” ).
Unlike conjoined human twins, however, each siphonophore clone contains only the anatomy necessary for it to perform one or a few tasks. Some individuals serve as fishing lines and stomachs, others as gonads, and others as thrusters. The clones share resources or services with each other to make the whole animal work. Siphonophore clones represent an alternative path to forming a large, complex multicellular organism -- one that strikes those of us whose ancestors took a radically different path as deeply alien, and often bizarrely beautiful.
Happy New Year, readers. I’ll see you in 2017.
