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An Elegy for Not Exactly Rocket Science


Everything ends, so let’s start there. Effective immediately, I’m closing down this blog.

I’m not going anywhere, though; since 2015, I’ve been working at The Atlantic as their first staff science writer, and will now be focusing fully on my writing there.

Having ended, let’s return to the start. I started this blog—Not Exactly Rocket Science—in August 2006, on little more than a whim. It was my first proper foray into science writing. I told my friends that I wanted to get regular practice, and to build up a portfolio of work that I could then show editors. But mainly: I really wanted to write. I had an urge to explain, to describe, to tell stories—an itch that my day job at a cancer charity wasn’t scratching.

I’ve since written more than 1,800 pieces under its banner. At first, I wrote for free, to an audience that numbered in the low dozens. Then, I moved to a succession of paying communities: the ScienceBlogs network (then run by the now-defunct SEED magazine), the Discover blogs network, and finally National Geographic’s Phenomena.

This is where I honed my skills through nigh-daily practice, built my reputation, and taught myself how to do journalism. I started collecting links to the pieces I had read during the week. I won awards, including the National Academies Keck Award for Science Communication in 2010. Editors did contact me to do freelance work for them after reading my posts, conference organizers asked me to speak to their delegates, and social scientists wrote papers about the blog. Not Exactly Rocket Science has been the centrepiece of my career.

But everything ends.

Over time, as I wrote for more publications, and as I began to self-identify as a journalist rather than a science communicator, my approach to blogging also changed. More and more of the posts were fully reported, and the writing style skewed closer and closer to what I’d write in paying publications. And yet, for the longest time, Not Exactly Rocket Science remained the one place where I had control over which stories I should cover, and over how I should cover them. Blogging was freedom.

But The Atlantic, whose online writers have long fused the freewheeling ethos of blogging with the traditional rigours of journalism, now offers a similar freedom, combined with all the benefits of editorial support. Consequently, it’s where I’ve decided to devote all of my energy. It’s where Not Exactly Rocket Science will live on, in spirit if not in name.

This blog changed my life. It gave me a career. It cemented my desire to write. It connected me with communities that opened my eyes to the art of journalism and the realities of social justice. It led to friendship and love.

It’s ending now, but not really dying. It just became something else, right under my nose. (The same has been said for blogging in general in countless hot takes.)

In this final post, I’d like to sincerely thank: National Geographic for hosting Not Exactly Rocket Science since 2012; Virginia Hughes, Amos Zeeberg, and Jamie Shreeve for recruiting me into their various networks; to Carl Zimmer for being a constant source of encouragement since the very earliest days; and to everyone who has read my work over the last decade.

If you’d like to keep up with my writing, you can subscribe to this feed, or sign up for my email newsletter, The Ed’s Up.



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This Animal Tears Its Face Off to Open Its Mouth

There’s a small, tentacled freshwater animal called a hydra, whose mouth disappears every time it closes.

I really mean that: it disappears. When your mouth closes, the two halves are still distinct. No matter how tightly you purse your lips together, they’re still separate bits of flesh. The same is true for the enormous mouths of whales and the tiny ones of mice, the beaks of birds and the expandable jaws of snakes. But not a hydra—its closed mouth fuses shut to form a continuous, sealed sheet. In the words of one scientist,  “when a hydra closes its mouth, it obliterates it.”

Which means that whenever a hydra opens its mouth, it must tear itself apart.

In Greek mythology, Hydra was a venomous, many-headed snake monster with amazing powers of regeneration. Real hydras… aren’t actually that far off. They’re small and not that terrifying, but their shape—a tubular body crowned by wavy tentacles—recalls the beast of mythology. Like their cousins, the jellyfish, sea anemones, and corals, they’re armed with stinging cells that fire venomous harpoons. And they do regenerate with incredible skill; some biologists have even suggested that they’re effectively immortal.  They are amazing creatures, which feature (along with their microbes) in my upcoming book, I CONTAIN MULTITUDES. But until recently, I had no idea about their weird mouths.

Hydra viridissima.
Hydra viridissima.
Frank Fox CC BY-SA 3.0

In the 1970s, scientists saw that hydras can open their mouths wider than the diameter of their own bodies, allowing them to swallow prey far larger than themselves. They also noticed that the mouth seemed to disappear whenever it closed. They couldn’t see it, not even with powerful microscopes.

In 1987, Richard Campbell from the University of California, Irvine discovered why: a hydra mouth is not a permanent opening. It constantly forms and vanishes. When it closes, a wide ring of cells around the edge of the mouth collapses into a small mound called a hypostome, with a rosette of 6 to 12 cells at its centre.  These cells are stapled together by small junctions, so that not even a tiny pore remains between them.  In many ways, Campbell wrote, closing the mouth is very much like healing a wound.

When a hydra opens its mouth, these rosette cells slowly stretch and flatten over a minute or so. Finally, a small rupture appears between them. As soon as this happens, the mouth quickly snaps open. Within half a second, a gap that extends between two or three cells becomes a gaping maw with hundreds of cells around its margin.

Campbell described this process in huge detail using careful microscopy but there was still a lot he didn’t understand. Now, three decades later, Eva-Maria Collins from the University of California, San Francisco has discovered more about this process, by studying genetically engineered hydra that have glowing molecules in their heads.

Hydra’s hypostome contains contractible filaments called myonemes, which are arranged in rings and spokes, much like a spider web. Collins proved that the mouth opens when the spokes contract, and presumably closes when the rings do. (A similar process dilates and constricts the pupils in your eyes.) Her team also showed that the cells around the opening mouth don’t rearrange themselves, as Campbell suggested. Instead, they just change shape, becoming longer and narrower to accommodate the creature’s widening gape.

Of course, none of this explains why the hydras have evolved such a weird way of opening and closing their mouths. Slaying the mythical Hydra was the second of Hercules’ great labours. And understanding the biology of real hydras is proving to be no less a feat.