Fish are, in a lot of ways, like humans. They're amazingly diverse. They have well-defined senses of taste and smell. They often travel in groups. They work really well with olive oil.
One other way fish are like us? They're also shedding cells, constantly. But while humans' cells generally slough off into air, the fishy ones end up in water. This leads to what one scientist refers to, accurately if somewhat horrifyingly, as "a soup of cells" in the sea. The ingredients of said soup? "Skin, damaged tissues, and ... body wastes."
The mixture is technically called eDNA, and you'd be forgiven for thinking that the "e" stands for "ewwwww." (It actually stands for "environmental.") And while you may prefer not to think about the stuff when planning your next beach vacation, eDNA could prove to be wonderfully useful. For science!
Traditionally, when researchers have needed to take censuses of the marine life populating particular areas, they've had to do it the old-fashioned way: by going out and sampling, netting animals or simply cataloguing them in their habitats. This is inefficient for obvious reasons. And eDNA—all that coded genetic material, just rolling in the deep—could obviate the need for it.
To test that potential, researchers at the University of Washington recently put eDNA sampling techniques to use. For that, they turned to a nicely concentrated source of that maritime genetic material: the enormous Open Sea Tank at the Monterey Bay Aquarium, which houses 13,000 live fish within 1.2 million gallons of water. From those contents, they extracted just two pint-sized glasses of water. (The researchers said, in retrospect, that their sample could have been smaller.) To zero in on vertebrate DNA, the researchers used a set of "primers"—molecular probes—that were designed by another group the year before they conducted their study.