Friday, August 19, 2011

A Boatload About Eupleura caudata (Say, 1822)

Splashing my bare feet in the edge of the summer ripples on
                   Paumanok’s sands, . . . .
                               ~ Walt Whitman, Leaves of Grass

On my annual pilgrimage to the fossil-forsaken wilds of Long Island (New York), I am free to spend days embracing the abundance that nature nicely brings to my summer cottage door (and, often, across my doorsill).  This has been a summer of seashells, fossil and otherwise, largely because I began my visit with a purchase at a local gem and mineral show of an inexpensive fossil shell of Aporrhais pespelecani (Linnaeus, 1758), that had been found at a Pliocene (5 to 3 million years ago) site in Italy.  According to the Paleobiology Database, A. pespelecani has been collected from European sites dating back to the Miocene (23 to 5 million years ago).  (More on the Database at the end of the posting.)  The fossil specimen below is 1 ¾ inches in length.   A. pespelecani is extant, living in the eastern Atlantic.

The wildly flowing “lip” of this gastropod (snail) shell generated its common name – Pelican’s Foot Shell – as well as its scientific name.  The genus portion is from the Greek aporrheo meaning to “flow away” and its species name is from the Latin pes and pelecani for, what else, “pelican’s foot.”

The outstretched wing (or foot) on these shells has inspired artists for centuries.  The website Gastropoda Stromboidea offers a wealth of information on, and historical images of, members of the Stromboidea, including the A. pespelecani.  The plate (shown below) from Niccolò Gualtieri’s Index Testarum Conchyliorum, quae adservantur in Museo Nicolai Gualtieri (1743), is particularly enjoyable.  Geologist Mark Wilson on the blog Wooster Geologists aptly described it as appearing to show the shells dancing.  (Source credit for the Gastropoda Stromboidea site is provided at the end of this posting.)

Now, that’s the European style of free flowing skirt on a gastropod.  There’s an American Aporrhais but the pictures I’ve seen suggest it’s much less attractive, somehow seeming to overdo the extended skirt.  Besides, A. occidentalis doesn’t appear on my Long Island beaches.  So, I’ve spent my time chasing the modestly flaring skirts of the shells of the gastropod Eupleura caudata (Say, 1822), the Thick-lipped Oyster Drill, a marine snail that does frequent Flander’s Bay, a short walk or bike ride away.  These sands teem with animal life of the invertebrate variety and with copious evidence of the death of same.  Here I can readily find the shells from E. caudata, with its two varices (prominent ridges), one of which flares outward as a skirt on the rim of the aperture on the underside.  Its style is decidedly more demure than that of its taxonomically and geographically far, far distant cousin A. pespelecani, though I think it can dance a gentle dance.  The specimen pictured below is 5/8 inches long.  The picture does not do it justice.

That I favor its attractive search image might contribute to the preponderance of E. caudata in my bags, far in excess of the spindle-shaped shells of its nearer cousin Urosalpinx cinerea (Say, 1822), the Atlantic Oyster Drill, an imbalance contrary to the conchology literature for this area.  Or perhaps the robustness of E. caudata shell enables it to more easily survive intact the constant scouring of the waves on sand.  I am thankful for what the bay gives me.  The U. cinerea pictured below is 11/16 inches long.  The lip curves in; certainly stylish in its own right.

I originally took the beach picture that opens this posting to highlight how E. caudata stands out, at least to me, from among all of the other distractions on the beach.  In this small stretch of sand, I’d spotted two E. caudata among the various shells on the sand; the others mostly Crepidula fornicata (Linnaeus, 1758), the Common Slipper Shell.  But, it’s now a testament to the limits of my “fine-tuned” search image.  As I put in the black arrows to mark the E. caudata shells in the beach picture, I spotted yet another one of these Drills.  The uncollected and embarrassingly obvious intruder is the smaller one of the pair on the left.

Admittedly, E. caudata has a well-earned reputation as a voracious killer, preying on young oysters and other bivalves by drilling a precise small hole through their shells to gain access to the soft animals within.  In its defense . . . Hey, that’s life.  Besides, cousin U. cinerea is more the villain in the Muricidae family, being the acknowledged devastator of oyster seed crops in Long Island Sound and the Chesapeake Bay.

Names are all important.  As noted, E. caudata carries the unflattering common name of “Thick-lipped Oyster Drill” – an unimaginative description of the outer edge of its aperture joined with a literal description of how it earns its living.  In contrast, the genus portion of its scientific name sings a bit, praising the aesthetic virtues of its shell, specifically that flaring varix.  Eupleura – the Greek eu means “good,” “well,” or “pleasing” and pleura means “side.”  “Pleasing side” or “pleasing sided” – I like it.  (The species name cauda reverts to the mundane – Latin for “tail.”)

As conchologists William K. Emerson and Morris K. Jacobson note, “Common names may change from place to place, scientific names from time to time.”  (Shells from Cape Cod to Cape May with Special Reference to the New York City Area, 1971)  The “Say” in the extended scientific name for E. caudata refers to Thomas Say (1787 – 1834) who, in a volume published in 1822, was the first to describe this creature and its shell and U. cinerea, though, as the parentheses note, the names he gave them changed after his publication.

When Say published on what is now known as E. caudata, he expressed displeasure in the generic name he felt compelled to apply, Ranella, a “generic name I think objectionable, inasmuch as it borders too closely upon Renilla, which designates a genus of the class Polypi of Lamarck.”  He characterized this animal as a “rather common species.”  (An Account  of Some of the Marine Shells of the United States, Journal of the Academy of Natural Sciences of Philadelphia, 1822, p. 236-237)

I must shamefully admit that, until I explored this taxonomic history, Thomas Say was unknown to me.  My great loss.  Say has been called the "Father of American Entomology," the "Father of American Conchology," and the "Father of American Zoology," titles David M. Damkaer describes as “well deserved.”  (The Copepodologist’s Cabinet:  A Biographical and Bibliographic History, Vol. 1, 2002.  A copepod is a member of a group of widespread, small crustaceans.)  According to Damkaer, Say was the first American entomologist to be considered equal to European entomologists; in the course of his life, Say identified over 1,500 new insects.  His descriptive volumes on American conchology broke new ground and have stood the test of time.  For the latter portion of his life, “Thomas Say was the highest authority on North American mollusks, insects, and crustaceans.”  (Damkaer, p. 172)

His was a fascinating albeit brief life.  A member of a Quaker family of some means, Say thwarted his father’s efforts to steer him to apothecary, partly by failing at the business.  Instead, his interest in natural history consumed him.  Say joined a Philadelphia circle of men with scientific interests that founded the Academy of Natural Sciences of Philadelphia in 1812.  (Guide to the Microfilm Publication of the Minutes and Correspondence of the Academy of Natural Sciences of Philadelphia 1812 – 1924, Venia T. Phillips, 1967)  Say ventured far afield in his natural history pursuits, exploring areas in the South, and serving as zoologist on two expeditions to the West.

In the winter of 1825 - 1826, he joined several of the Academy of Natural Sciences’ leading scientists who, along with many other educators, artists, and students, journeyed by riverboat to Robert Owen’s communal experiment in New Harmony, Indiana.  Called by Owen, the “boatload of knowledge,” this drawing of intellectual talent to New Harmony was in support of his belief that social reform necessitated widespread distribution of knowledge.  (Donald E. Pitzer, The Original Boatload of Knowledge Down the Ohio River:  William Maclure's and Robert Owen's Transfer of Science and Education to the Midwest, 1825-1826, Ohio Journal of Science, Vol. 89, No. 5, 1989)  The loss of talent negatively affected the Academy of Natural Sciences for many years, with the result, according to Damkaer, that “the U.S. center of natural history shifted to New Haven and Cambridge . . . .” from Philadelphia.  (Damkaer, p. 172)

In New Harmony, Say had responsibility for “Literature, Science, and Education.”  During the brief years left to him, Say completed his masterwork on shells, American Conchology, nearly all of it published in New Harmony during 1830-32.  Of the 68 plates for the work, 66 were by his wife Lucy whom he had married in 1827; she had been a fellow traveler on the “boatload of knowledge.”  Following Thomas’ death in 1834, she returned east and, in 1841, was admitted to the Academy of Natural Sciences, its first woman member.  (The University of Southern Indiana provides a useful website introducing the New Harmony experiment.)

Here is Lucy Say’s (“Mrs. Say” as she signed it) illustration for the Ranella caudata in Thomas Say’s American Conchology.   (The image is taken from The Complete Writings of Thomas Say, on the Conchology of the United States, edited by W. G. Binney, 1858.)

Not very impressive, I’m afraid.  The Maryland Geological Survey published a nice drawing of E. caudata in 1906, showing it as a fossil from the Pleistocene (3 million to 10,000 years ago).  (W. B. Clark, et al., Volume VI, Maryland Geological Survey, 1906.)

Unfortunately, E. caudata just has not inspired artists the way A. pespelecani has.

As for this gastropod’s fossil record, it seems to coincide generally with that of A. pespelecani, at least in terms of when it appears.  In 1890, paleontologist William Healey Dall summarized the taxonomic history of E. caudata and noted that it occurred as a fossil, possibly in the Miocene (23 to 5 mya), but definitely in the Pliocene (5 to 3 mya, South Carolina and Florida), and in, what he termed, the “Post-Pliocene” along “most of the Atlantic coast.”  (Tertiary Fauna of Florida, with Especial Reference to the Miocene Silex-Beds of Tampa and the Pliocene Beds of the Caloosahatchie River, Transactions of the Wagner Free Institute of Science of Philadelphia, Volume 3, August 1890.)  The Paleobiology Database basically confirms Dall, citing examples in the fossil record of E. caudata going back to the Miocene.

Dall went on to consider the distribution of the few Eupleura species that have appeared on either coast of the United States, and noted that on each coast there was a predominant representative joined with another possible species exhibiting greater physical and geographical variability.  He concluded that this group “though containing but few species, presents as pretty a series of modifications in space and time as any evolutionist could wish to see.”  (p. 144)

Which for me prompts a fundamental question, why did a flaring lip or edge evolve on A. pespelecani and E. caudata?  For defense?  For stability?  Because they accompanied genetically some other useful features that evolved in these organisms?  Why so dramatically on the former and not the latter?  Different environment, different pressures?  I need more knowledge.

Additional Source Information

For the sake of consistency with the scientific names for these organisms, I’ve relied exclusively on the World Register of Marine Species (otherwise known as WoRMS).

The Paleobiology Database, originally funded by the National Science Foundation and now by the Australian Research Council, is a very useful website providing taxonomic information (though not always in sync with WoRMS) and collection information for animals and plants regardless of geological age.

The Gualtieri image is from the Gastropoda Stromboidea website:  Ulrich Wieneke and Han Stoutjesdijk (Eds.), "Aporrhais pespelecani". In: Gastropoda Stromboidea. modified: August 16, 2011, at 08:53 PM, URL: (accessed: August 18, 2011, at 07:00 AM).

For information on these various shells, I relied primarily on an idiosyncratic collection of guides (it’s what the mildewy library in my summer cottage, the local library, and a hopelessly messy used bookstore had to offer).  In addition to Emerson and Jacobson’s Shells from Cape Code to Cape May (cited earlier), I used R. Tucker Abbott’s How to Know The American Marine Shells (1961); Kenneth L. Gosner’s A Field Guide to the Atlantic Shore (a Peterson Field Guide) (1978); and Emerson and Jacobson’s The American Museum of Natural History Guide to Shells:  Land, Freshwater, and Marine, from Nova Scotia to Florida (1976).  This last is particularly informative but generally only if you’ve already acquired some knowledge elsewhere and identified the shell at hand.

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