Dr. Rob Dillon, Coordinator

Thursday, January 5, 2023

The Helisoma from the Black Lagoon!

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2023c)  The Helisoma from the Black Lagoon!  Pp 297 – 306 in The Freshwater Gastropods of North America Volume 7, Collected in Turn One, and Other EssaysFWGNA Project, Charleston, SC.

Last month [1] we toured all around Tallahassee and its immediate environs with the Comte de Castelnau, trying to figure out where The Count might have found a planorbid shell he gifted to John Clarkson Jay in 1838.  Jay described that peculiar flat-topped shell as Paludina scalaris, making wherever His Excellency might have picked it up the type locality of a species widespread and common throughout peninsular Florida.  And related in some very close way to Helisoma duryi (Wetherby 1879), which has been spread throughout the world.

Well, as the sun set on our first day of exploration, we had indeed found a couple Helisoma populations, both of which (alas!) bore disappointingly planispiral shells of dirt-common duryi morphology.  To find a population bearing the flat-topped “scalariform” morphology, we had resolved to venture further afield.


South and east of Tallahassee extend vast, marshy hinterlands drained by the St Marks River, with its primary tributary the Wakulla.  Although the formal appellation of “Everglades” has today been reserved for regions much further south down the Florida peninsula, much of the St Marks / Wakulla system might well have been colloquially referred to as everglades by its nineteenth-century denizens [2].  The hydraulics of the region are most unusual.  Picking up our story once again, in the words of Count Castelnau [3]:

"This river [the St. Marks] rises in Georgia, crosses Lake Mikasouky, sinks underground and soon comes forth as a pond at Brookhaven."

That area where the St. Marks “sinks underground” is today preserved in Natural Bridge State Park, about 13 miles SE of Tallahassee (G, map below).  In March of 1865, less than thirty years after The Count’s visit, a joint expeditionary force under the command of Maj. Gen. John Newton landed at the St. Marks Lighthouse 10 miles downstream and marched north intent on capturing the state capitol.  Newton was repulsed at Natural Bridge by a combined force of Florida cavalry, artillery, and militia, including cadets from the institution of higher learning that would become Florida State University.  Tallahassee was the only Confederate capitol east of the Mississippi River that did not fall to Yankees during the war.

I found The St Marks River forbiddingly black and deep as it enters Natural Bridge State Park, with very little freshwater gastropod habitat in evidence.  But in the nearby Natural Bridge Spring I recorded eight species, including more Helisoma bearing disappointingly-planispiral shells of the duryi type [4].

Continuing downstream on the St Marks River, The Count apparently visited the town of Magnolia, founded by four brothers from the state of Maine as a cotton trading port.   The town is classified as “extinct” by the state of Florida today, but even by 1837, it was apparently struggling:

"Magnolia is a little village, if this name may be given to two or three houses, situated seventeen miles from the Gulf of Mexico on the St. Marks River; it was built in 1827. It is almost abandoned today because of fear of the Seminole Indians who several times have committed massacres in the vicinity. The soil is fertile and the banks of the river are charming."

The historical footprint of Magnolia is approximately 1 mile north of the present-day town of Newport, where US98 crosses the St. Marks River (H).  I couldn’t find any public access to the river in Newport, but no decent freshwater gastropod habitat was visible from the bridge in any case, so screw it.


But now for the highlight of our visits to Florida, both of the Count’s in 1837 and my own in early 2021.  About 13 miles due south of Tallahassee is the aquatic wonderland of Wakulla Springs, “the largest and deepest natural spring in the world [5].”  Castelnau made his approach via water, rowing upstream from the town of St. Marks “by great effort, through snags.”

"Our little expedition left St. Marks at sunrise, and having gone around the point where the old fort is, entered Wakulla River; it is at first very wide and on its marshy shores there are a few scattered pines…  We had to struggle against a current of about a league per hour; the shores are very marshy and flooded, the river bed is covered with high grass which blocks the passage; in some places very big bushy canes also increase the difficulty of travel by water. We soon arrived among vast cypress groves whose trees are grouped in the form of islands; everywhere fallen tree trunks blocked our way."

I launched my kayak into the Wakulla River at the Shadeville Road bridge (I) and spent a lovely couple hours sampling the clear, cool, rich waters about three miles downstream from the spring.  I was especially charmed by the big Nerita reclivata grazing across the surfaces of the emergent Sagittaria grass beds, the first freshwater nerites I had ever seen in the wild [click to download an action shot.]

The freshwater gastropod fauna was otherwise disappointing, however; a gigantic population of grotesque Melanoides tuberculata outnumbering the native Pleurocera floridensis about a zillion-to-one.  I found no living hydrobioids, indeed counting myself lucky to net up a singleton Notogillia shell.  As for Helisoma, I was able to find exactly N = 2 in two hours of effort, both bearing entirely unremarkable shells of planispiral morphology.


And any thoughts I might have entertained about kayaking upstream to the springhead were dashed by a curtain of fencing hung across the entire width of the river above the bridge, festooned with signage most uncordial.  I loaded my kayak back into the truck and completed my journey to Wakulla Springs in routine, 21st century fashion. 

"The spring is oval in form and three hundred feet wide. By taking soundings we found that it was 76 feet deep. We were told however that in some places it was 100 feet deep; its water is wonderfully pure, and one can distinguish the smallest objects that are on the bottom;  Huge flocks of birds came to give life to the scene, we noticed especially among them beautiful herons of a dazzling white, pelicans with huge beaks provided with a big pocket below them, numerous long legged water fowl, the pretty Carolina parrakeet, etc., etc."

The Count did not mention any human residents of the area at his visit in 1837, but by 1875 enterprising locals were hosting guests and offering glass bottom boat tours of the spring.  Large scale commercial development was delayed until the 1920s but kicked into high gear in 1934, when financier Edward Ball purchased all the acreage around the spring and built a world-class resort hotel.

Wakulla Springs hosted US Army training maneuvers during World War II, including the detonation of underwater explosives [6].  In the postwar heyday that followed, the springs served as the filming location for at least one or two Tarzan movies, plus the 1954 cult classic, “Creature From The Black Lagoon.”  The property was acquired by the Florida State Park system in 1986, who have continued to run the hotel, beach, and boat tours very much in business.

Paying my $4 admission price as I passed through the contact station, the ranger glanced to the back of my pickup, noticed my kayak, and inquired, suspiciously, “You’re not planning to launch that in here, are you?”  “Gracious no!” I replied, “Such thoughts could not be further from my mind.”  “Good,” he cautioned, “The springs are a protected natural area.”  Protected from biologists in kayaks, apparently, but not from glass bottom motorboats or amphibious combat vehicles?


I had planned a rather unconventional itinerary for my visit, stopping first near the park entrance at the Sally Ward Spring Run (J). It materializes that there is a small, unfamous, and relatively ordinary spring in the cypress swamp upstream from the main tourist attraction, feeding into the spectacular head of the Wakulla River, within which the gill-faced Creatures lurk and upon which the glass-bottomed boats motor.

I found the malacofauna of the spring run similar to that I had just sampled in the main Wakulla River three miles downstream, although healthier [7].  And once again, dwelling on the muddy margins of the stream I found a sparse Helisoma population bearing shells of quite unremarkable, planispiral morphology, no different from the Helisoma I had seen at the Shadeville Rd bridge (I), or at the Natural Bridge Spring earlier in the morning (G), or indeed, on my explorations around Tallahassee the previous day.

Sally Ward Spring
Preliminary scouting work complete, I parked my truck at the back of the main parking lot for the tourist attraction and shucked off my hip waders so as not to attract attention, selecting instead a pair of well-worn Converse that I didn’t mind getting wet. I left my dipnet in the truck for the same reason, fearful that any overt show of scientific activity might be interpreted as threatening to the “protected natural area.”  Then putting my hands in my pockets, I strolled casually toward the waterfront (K).

The swimming beach was quiet on the brisk February morning of my visit and the tour boats not running.  But my attention was called to a hive of activity around the diving platform shown at the far left in the photo above.  Joining the throng on the top deck I was able to spy several manatees floating motionless in the crystalline waters below.


Oddly enough, however, I found myself more enchanted by the rooted-submerged macrophytic flora of the spring bottom than by the charismatic megafauna floating over it.  The waving jungles of Sagittaria and Vallisneria interspersed with white sand bottom were simply magical.  Pretty little fish and minnows nibbling about everywhere.  A coot paddled under my gaze, oblivious.  Where the hell are the snails, I thought to myself.


Where the hell, indeed?  I waded the entire shoreline accessible from the developed side, including weedy margins and all around the docks, to a depth of a foot or so, and did not find so much as a crap Physa.  Not a limpet on a leaf.  I can’t remember the last time I was skunked so thoroughly for so much effort.


Ah, but.  Around the shorelines of the Wakulla Spring pool one could hardly fail to note extensive deposits of relict shells.  And common among those relicts were Helisoma shells of the exact flat-top morphology demonstrated by the specimen presented to John Clarkson Jay by Comte de Castelnau in 1837.  I feel certain that Wakulla Springs is the type locality of Paludina scalaris Jay 1839.  For this conclusion I offer four lines of support:

Beach at Wakulla Springs

First, it seems quite possible that a living population of Helisoma scalare may inhabit Wakulla Springs today, and I simply missed it.  My readership will remember that the population of flat-topped Helisoma I sampled at the Forty-mile Bend were cowering in aquatic vegetation submerged several feet below the water surface [5Oct20].  I was only able to collect them by net, from a kayak.  Absent either of these tools in February of 2021, and stuck on the highly-disturbed south shore of the spring, I was simply unable to sample the habitat adequately.


Second.  Even if no flat-topped Helisoma population inhabits Wakulla Spring today, it is certainly possible that a living population existed in 1837 [8], subsequently extinguished by rampant commercial development, the glare of Kleig lights, and the underwater demolition necessary for successful amphibious assault.  Those relict shells I collected perhaps a foot above the waterline of the springa pool in early 2021 were not necessarily old.  In addition to the Helisoma, the figure above depicts one Pleurocera floridensis shell and two shells of Melanoides tuberculata, an exotic not recorded from anywhere in Florida until 1966 [10].  Might my chalky-white Helisoma scalare shell date but only to circa 1966, as well?


Third, even if no living population of Helisoma inhabited Wakulla Springs in 1837, the type shell presented by the Comte de Castelnau to John Clarkson Jay in 1839 was not live collected, either.  Indeed, it would seem more in keeping with the sensitivity of French nobility to pick up a clean white shell from the beach than yank some greenish-brown booger from the weeds, am I right?  That is Jay's AMNH type specimen refigured under the Creature mask way up at top of the present essay, to refresh your memory.

And finally.  I have been unable to find any scalariform Helisoma anywhere else The Count might have visited in 1837.  Of the ten other Castelnau sites I re-visited in 2021, six yielded no Helisoma at all, and four yielded Helisoma bearing unremarkable planispiral morphology.


All of which brings us back, one more time, to the question I’ve been nibbling around the edges of for nine essays now, and still not properly bit.  What is the relationship between Helisoma scalare and all those populations of large planorbids bearing unremarkable planispiral shells, traditionally identified as Helisoma duryi?  Next time we’ll answer that question.  I promise.


[1] If you’re just joining us.  This is the ninth essay in a long-running series that had its roots in 2005, picked up steam in 2020-21, and just resumed last month.  I won’t suggest that you go back and read the entire series unless you’re seriously interested in the science.  But the present essay won’t make much sense unless you’ve read my 6Dec22 post, at the minimum:

  • Shell morphology, current, and substrate [18Feb05]
  • Juvenile Helisoma [9Sept20]
  • The Flat-topped Helisoma of The Everglades [5Oct20]
  • Foolish things with Helisoma duryi [9Nov20]
  • The Emperor Speaks [3Dec20]
  • Collected in turn one [5Jan21]
  • Dr. Henry A. Pilsbry was a jackass [26Jan21]
  • In the Footsteps of the Comte de Castelnau [6Dec22]

[2] It will be remembered from last month’s essay [6Dec22] that Jay gave the type locality of Paludina scalaris as “The Everglades of Florida.”  And it will also be remembered from [5Oct20] that regions around Tallahassee do not qualify as “Everglades” today.


[3] This month’s Castelnau quotes are extracted from:

  • Castelnau, F., A.R. Seymour and M.F. Boyd (1948) Essay on Middle Florida, 1837 – 1838.  The Florida Historical Quarterly 26(3): 199 – 255.

[4] The freshwater gastropod fauna of Natural Bridge Spring: Viviparus goodrichi, Pleurocera floridensis, Spilochlamys conica (topotypic!), Amnicola limosa, Physa carolinae, Laevapex fuscus, Ferrissia fragilis, and the planispiral Helisoma.


[5] Here I’m quoting wakullasprings.org.  They did not share any data on the millions of other springs they must have measured worldwide to arrive at their conclusion.


[6] US Army training video, from the State Library and Archives of Florida:

Wakulla Springs Military Training and Underwater Explosions

[7] The Sally Ward Spring Run malacofauna is dominated by large populations of Pleurocera floridensis and Spilochlamys conica, with Melanoides nowhere in evidence.  Both Ferrissia rivularis and Laevapex cling to the macrophytes blades, with planispiral Helisoma and Physa carolinae populations grazing sparsely at the stream edges.  Scrappy evidence of Viviparus & Campeloma.


[8] My search of the worldwide idigbio database [9] for Planorbidae + Wakulla returned a single record in the University of Florida Museum that might be of interest: UF4855, collected from Wakulla Springs by J. Richardson in 1938.  That lot, identified as “Planorbella duryi,” demonstrates vanilla planispiral shell morphology, alas.  I thank Roger Portell for his help with this question.


[9] For more about the IdigBio internet resource, see:

  • 20 Years of Progress in the Museums [22May19]

[10] Clench, W.J. (1969) Melanoides tuberculata (Muller) in Florida.  Nautilus 83: 72.