The Last Word On Nothing

Consistent with my policy of running posts that take me, virtually anyway, out of the pandemic present to somewhere or sometime that’s interesting and wide-angle, I offer you the Chesapeake Bay: born in violence, growing up geologically and then sociologically, and now hitting the present with utter tomfoolery. And revelation. This first ran March 31, 2011.

The Chesapeake Bay was born as the Susquehanna River.  Around 35 million years ago, an asteroid apparently smacked into what is now eastern Virginia and left a 50-mile-wide crater, a sink into which all the rivers – mainly the Susquehanna but also the Potomac and lesser rivers — coming east out of the Appalachians naturally flowed.  Millennia came and went, ice ages came and went, and about 8,000 years ago melting glaciers raised the level of the Atlantic enough that, over the next couple of thousand years, it flooded into that old crater and on up the river valleys and created the Chesapeake Bay.  I’m telling you this story mostly because I like it but please, bear with me, I do have a point.

A couple years back, during a day cruise around the Channel Islands, we found ourselves surrounded by a sizable school of common dolphins. (Not a mega-pod, alas, but even a few dozen dolphins is a pretty awe-inspiring sight.) Common dolphins are, as their name suggests, among the most abundant marine mammals in the world; it’s probably easier to name the coastlines where they don’t occur than where they do. (Here’s a range map, for the curious.) They’re famously social, energetic, and playful, and the pair above, along with their comrades, weaved around our vessel for a good 15 minutes, flying through the Pacific in graceful synchrony.

Despite their ubiquity, common dolphins are still a bit of a mystery. In 1994, Delphinus delphis, long considered a single species, was split into two, the long-beaked common dolphin (D. capensis) and the short-beaked common dolphin. The primary difference was — guess what? — the snout, which, in the long-beakers, “can be up to 10% of the total body size.” In 2015, though, the dolphin’s taxonomic story twisted again: Researchers declared Delphins capensis “invalid” on the basis of DNA evidence. All the world’s common dolphins allegedly belonged to Delphinus delphis, though the researchers did acknowledge the existence of a few subspecies, including D. d. bairdii, the eastern North Pacific long-beaked common dolphin, whose name is as long as its rostrum.

Got all that?

I’m reasonably certain the animals we saw in the Channel Islands were long-beakers (they tend to spend more time around coastlines rather than the open ocean, and are apparently more, well, common around the islands than the short-beakers), but I’ve been staring at dolphin photos for the last twenty minutes and feel no closer to a definitive diagnosis. If you’re a confident cetologist, get at me in the comments.

Photo: Ben Goldfarb