The tattoo on Cara Santa Maria’s inner right forearm isn’t exactly the kind of ink drunken sailors get. “Yeah, this is Archeopyeryx Lithographica,” she says of the pencil-length array of bones. “It’s actually the Berlin specimen, which is a pretty famous transitional fossil, because some people call it a bird, some call it a dinosaur. Personally, I like it because it’s kind of a fuck-you to creationists.”

Got it. It doesn’t take much time with Santa Maria to discern that almost everything is personal with her. Not that she’s touchy or overly self-involved. But her work as the writer, voice, and face of Huffington Post’s “Talk Nerdy To Me”—a weekly video series on science-related stuff that ranges from the topical (Tennessee’s anti-evolution law) to the evergreen (death)—meshes so thoroughly with her personality and passions (or are they obsessions?) that it’s nearly impossible to untangle the threads. For one thing, it won’t be a surprise—given her explanation of the tattoo—to learn that she’s a devout and outspoken atheist, and that this influences her coverage of everything from biology to the environment.

In January 2012, when HuffPost launched its science section, Santa Maria was elevated from a utility player in the site’s science-oriented programming to become the anchor of the “Talk Nerdy” vertical. With a master’s in neuroscience and a zeal for research, Santa Maria was certainly qualified. But her boss, David Freeman, the former managing editor for health topics at CBSnews.com who was brought in to overhaul HuffPost’s science coverage, says her mandate was “not just to alert people to important issues, but to make it fun, accessible, and playful.”

Delivering serious science coverage in a playful package was a tricky, and critical, challenge for HuffPost, as its various efforts on the beat prior to launching the new section had been widely derided—by this publication and others—for trafficking in pseudoscience and New-Age hooey. Most problematic were a number of misleading columns that made spurious connections between things like vaccines and autism, and antibiotics and cancer.

As it happens, playful comes as naturally to Santa Maria as her commitment to good science. The evidence, once again, is in the ink. Tattooed on the left side of her rib cage is a quote from her hero, Carl Sagan—“We are a way for the cosmos to know itself”—which to her means “there is no greater consciousness,” only us and nature. And she notes that she’s also got a skull and crossbones on board. Where? “I’m not going to tell you,” she says. As a teenager, Santa Maria got inked up, not defiantly—her mom accompanied her—but “because it was cool.”

In the same way, “Talk Nerdy” surrounds its intellectual ambitions with thrashy guitar, whizzing graphics and animation, and Santa Maria herself, whose flirtatious eye contact with the camera enforces an enthusiasm that she seems barely able to contain. On Halloween, she donned various costumes—werewolf, zombie, etc.—for a show about rare syndromes.

The “Talk Nerdy” formula—a smarty-pants expert who also happens to be charming and attractive on camera—is pretty standard. But the Web adds a useful interactivity to this proven broadcast strategy. HuffPost wouldn’t provide specific traffic numbers for “Talk Nerdy,” but its active comments section suggests what should be obvious: Santa Maria plays well to the male-heavy, geeky, and obsessive nature of so much of the Internet. (For the record, she says her most-viewed episode to date is “What Happens When You Die?” an exploration of the brain chemistry of impending death. Its comments section was closed at 7,728.)

It wouldn’t be entirely accurate to say that Santa Maria caused a stir one day last November when she arrived on the sunny terrace of a sandwich joint near her office in a new-media ghetto of Beverly Hills. But studiously casual heads did turn. Whether that was due to her ration of online visibility or just the overall aesthetic is hard to say.

Fred Schruers is a freelance writer based in Los Angeles.