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Sometimes themes or topics emerge when you aren’t looking for them — and yet, they are oddly perfect for the moment. I credit this month’s topic to my mother, who, like me, is a lover of poetry. Unbeknownst to her, on the day she inspired this topic, I had just written my first “Intertidal” for this paper about Eric Carle’s stories “A House for a Hermit Crab” and “Mr. Seahorse,” using the hermit crab outgrowing its shell as a metaphor for my column finding a new home in the Anchor. The poem she shared with me is about another shelled marine creature. “The Chambered Nautilus” was written by the American poet Oliver Wendell Holmes Sr.
While both have shells, a chambered nautilus (Nautilus pompilius) is quite a different creature than a hermit crab. A hermit crab is a crustacean that, like its relatives — lobsters, shrimp and barnacles — has a hard exoskeleton. A nautilus, however, is a squishy-bodied animal like its cephalopod relatives — squid, cuttlefish and octopuses.
All cephalopods evolved to “lose” their shells except for the nautilus. Its lovely spiraled and uniquely chambered shell evolved around 500 million years ago and hasn’t changed much. The chambered nautilus found in the Indian and Pacific oceans today look much like their relatives who lived at the time of the dinosaurs.
While Nautilus pompilius doesn’t live in the Atlantic Ocean, its more modern relatives do. They’re not as easy to find as a scurrying hermit crab, but I have been lucky enough to see a few octopuses and squid right off our coast. I had not realized until recently their connection to an ancient relative, the chambered nautilus.
In Holmes’ poem, the nautilus, like the hermit crab, gets too big for its shell. But, rather than leave its current one in search of a new one, it builds an addition. This reminds me of the classic New England farmhouse that was built as a small saltbox and became a sort of jalopy of little added cubicles, some stacked and some put end to end, that expanded the space over time to meet the needs of a growing family. The allegory here is that a living creature is always growing in some way and needs new capacity to accommodate this growth. It’s a lovely idea, particularly for an adult who stopped physically growing many decades ago and is constantly amazed by the continued growth of her teenage daughters!
The difference between the farmhouse model and that of the nautilus is that the nautilus isn’t exactly making its living space bigger. In fact, it closes off each old chamber of its shell before moving into a new one. Like the hermit crab, the nautilus abandons its old house and keeps it as a kind of ghostly reminder of its past life — perhaps a reminder of its recent progress toward something new and improved. “Leave thy low-vaulted past! / Let each new temple, nobler than the last / Shut thee from heaven with a dome more vast,” writes Holmes.
This method of sealing off the old and building anew allows the nautilus to make a fresh start while staying physically connected to what came before. The old chambers are not useless, however. They serve a functional purpose, allowing the nautilus to migrate up and down in the water column by trapping air in each chamber to control its buoyancy.
Perhaps the metaphor in Holmes’ poem is evolution itself. He concludes the poem with the lines, “Till thou at length art free, / Leaving thine outgrown shell by life’s unresting sea!”
Cephalopods did, in a sense, leave their shells behind when, around 300 million years ago, some of them evolved into “modern” creatures like squid and octopuses. That’s when they evolved things like complex eyes, highly functional tentacles, and the ability to change color and pattern in mere seconds — new skills that were necessities without the protection of a shell. These seemingly vulnerable creatures have been found to be some of the most intelligent on Earth.
I’m grateful for Oliver Wendell Holmes’ reminder of the wonder of nature’s ability to constantly and unceasingly evolve new capabilities, and how this might inspire us to think about our own capacity for continuous growth.
