Busyconidae

Perverse lightning whelk Sinistrofulgur perversum, copyright H. Zell.

Belongs within: Echinofulguridae.
Contains: Busycotypinae.

Crossing the Busycon
Published 28 October 2021

I must admit that when I think about the biodiversity hotspots of the world, the eastern seabord of the United States would not be among the first regions to come to mind. But for this post, I’m looking at a dramatic and eye-catching radiation of molluscs for which this is their centre of distribution. I speak of the giant whelks of the Busyconidae.

Left-handed whelk or lightning whelk Sinistrofulgur sinistrum, copyright Andrea Westmoreland.

Busyconid whelks first appeared in the waters of eastern North America during the early Oligocene, about 32 million years ago, in what was then the Mississippi Sea and is now the Mississippi River Basin. As the oceans receded from the Mississippi, they spread into the Gulf of Mexico and are now found between Massachusetts in the north and the Yucatan Peninsula in the south. Except for an introduced population of the channeled whelk Busycotypus canaliculatus that has become established in San Francisco Bay in California since the 1930s, the family has never been found elsewhere. These are remarkably large snails: smaller examples are still more than five centimetres in length, and the largest of all get close to a foot (Petuch et al. 2015). Mature shells have a large body whorl, generally higher than the visible spire, with a long siphonal canal. SCulpture of the shell, if present, is dominated by spiral elements, and the shoulder of the whorls may be marked by prominent carinae and/or spines. As is standard for neogastropods, the classification of this group has shifted around a bit over the years, whether treated as their own family or as a subfamily Busyconinae of the related families Buccinidae or Melongenidae. In a recent review of the busyconids, Petuch et al. (2015) recognised fifteen living species in six genera. The number of fossil species that has been described is significantly larger (over one hundred); not surprisingly, these large solid shells have an excellent fossil record. However, it is worth noting that some of the living species may be remarkably variable in shell morphology and I don’t know whether fossil representatives have been subject to the same systematic scrutiny.

Knobbed whelk Busycon carica, copyright Matt Tillett.

All busyconids are predators on bivalves, particularly on burrowing clams. In general, the whelk envelops its victim in its muscular foot and then uses the edge of the shell lip to open the clam’s shell, allowing the whelk to insert its radula and rasp out the clam’s flesh. The preferred method of opening the shell depends on the species of whelk and may be classed as ‘wedging’ and ‘chipping’. ‘Wedging’ is the most straightforward method and believed to be the more primitive; wedgers insert the shell lip into the gap between valves and directly force them apart and/or prevent the clam shell from closing. ‘Chipping’ is more involved and performed by members of the genera Busycon and Sinistrofulgur. In this method, the edge of the whelk shell is rhythmically pounded against the commissure between the clam shell valves, progressively wearing at the valve margins until enough of an opening has been made to insert the radula. The process may take multiple hours of patient hammering. Chipping requires more power and a heavier shell than wedging (chipping whelks may damage their own shell as well as the prey’s) but also allows the whelk to attack thicker-shelled clams.

Though each species of busyconid will generally use one or the other method of opening prey, there are borderline examples. Larger individuals of Busycotypus canaliculatus, usually a wedger, may adopt a process like chipping though their attacks on the prey shell are usually less systematic than true chippers. And while I haven’t found anywhere that says as much, I suspect that young chippers may spend the earlier parts of their life as wedgers untill they have developed the shell strength for chipping. Dietl (2004) suggested that chipping behaviour may have originated twice among busyconids, based on the fossil evidence of its traces left on clam shells. The modern chippers appear to derive from a single origin in the later Pliocene. However, evidence of an earlier and now seemingly extinct chipping lineage was also found in shells from the late Miocene. These earlier chippers seemingly did not belong to any of the modern chipping genera which are not known from the Miocene deposits in which chipped clams were found. Instead, Dietl proposed that the culprit was a large Busycotypus.

Channeled whelk Busycotypus canaliculatus laying a string of egg cases, copyright Eric Heupel.

Busyconid whelks have long been of significance to people living in areas where they are found. Not only are the shells eye-catching and ornamental objects in themselves, the animals are also harvested for food (though their meat is often sold under misleading names such as ‘conch’ or ‘clam strips’). Archaeological examples have been found of busycon shells being used for tools; Petuch et al. (2015) illustrate an example of a left-handed whelk Sinistrofulgur sinistrum shell with holes drilled into it that would have allowed it to be attached to a stick and used as a shovel. These animals are truly an icon of North America’s eastern seaboard.

Systematics of Busyconidae
Busyconidae [Busyconinae]PMB15
|--Spinifulgur Petuch 1994PMB15
| |--*S. spiniger (Conrad 1848)PMB15
| |--S. armiger Petuch 2004PMB15
| |--S. epispiniger (Gardner 1944)PMB15
| |--S. gemmulatum Petuch 1997PMB15
| |--S. nodulatum (Conrad 1849)PMB15
| |--S. onslowensis (Kellum 1926)PMB15
| |--S. perizonatum (Dall 1890)PMB15
| |--S. proterum (Gardner 1944)PMB15
| |--S. stellatum (Dall 1890)PMB15
| `--S. tampaensis (Dall 1890)PMB15
`--+--BusycotypinaePMB15
|--+--Sycopsis Conrad 1867PMB15, P12
| | |--*S. tuberculatum (Conrad 1839)PMB15
| | |--S. carinatum (Conrad 1862)PMB15
| | `--S. lindae Petuch 1988PMB15
| `--Turrifulgur Petuch 1988PMB15
| |--*T. fusiforme (Conrad 1839)PMB15
| |--T. aldrichi (Gardner 1944)PMB15
| |--T. atractoides (Gardner 1944)PMB15
| |--T. covepointensis Petuch 2004PMB15
| |--T. dasum (Gardner 1944)PMB15
| |--T. foerstei (Gardner 1944)PMB15
| |--T. marylandicum Petuch 1993PMB15
| |--T. prunicola Petuch 1993PMB15
| `--T. turriculus Petuch 1988PMB15
`--+--Lindafulgur Petuch 2004PMB15
| |--*L. lindajoyceae (Petuch 1991) [=Busycon lindajoyceae]KF22
| |--L. alencasterae Perrilliat 1963PMB15
| |--L. candelabrum (Lamarck 1816) [=Pyrula candelabrum, Busycon candelabrum, Fulgur candelabrum]PMB15
| |--L. lyonsi (Petuch 1987) [=Busycon (Busycoarctum) lyonsi]PMB15
| `--L. miamiensis (Petuch 1991)PMB15
|--Busycoarctum Hollister 1958PMB15
| |--*B. coarctatum (Sowerby 1825) [=Pyrula coarctata]KF22
| |--B. rapum (Heilprin 1886)PMB15
| |--B. superbus (Petuch 1994)PMB15
| |--B. tropicalis (Petuch 1994)PMB15
| `--B. tudiculatum (Dall 1890)PMB15
|--Busycon Röding 1798PMB15, BR05 [incl. Fulgur Montfort 1810BR05; Busyconini, Fulguridae, Fulgurinae]
| |--B. carica (Gmelin 1791)BR17 (see below for synonymy)
| | |--B. c. caricaPMB15
| | `--B. c. eliceans (Montfort 1810)PMB15 (see below for synonymy)
| |--B. alumense (Mansfield 1930)PMB15
| |--B. auroraensis Petuch 1994PMB15
| |--B. blakei Conrad 1855C64
| |--B. burnsi Dall 1890PMB15
| |--B. diegelae Petuch 2004PMB15
| |--B. duerri Petuch 1994PMB15
| |--B. filosum Conrad 1862 [incl. B. filosum var. tritonis Conrad 1863]PMB15
| |--B. gilmorei Petuch 1994PMB15
| |--B. maximus (Conrad 1839)PMB15
| |--B. montforti Aldrich 1909PMB15
| |--B. pachyus Petuch 1994PMB15
| |--B. radix Gardner 1944PMB15
| |--B. rucksorum Petuch 1994PMB15
| `--B. titan Petuch 1994PMB15
`--Sinistrofulgur Hollister 1958PMB15
|--*S. sinistrum (Hollister 1958) (see below for synonymy)PBM15
|--S. adversarium (Conrad 1862)PMB15
|--S. caloosahatcheensis Petuch 1994PMB15
|--S. contrarium (Conrad 1840) [=Busycon contrarium]PMB15
|--S. grabaui Petuch 1994PMB15
|--S. holeylandicum Petuch 1994PMB15
|--S. hollisteri Petuch 1994PMB15
|--S. labelleensis Petuch 1994PMB15
|--S. laeostomum (Kent 1982) [=Busycon laeostomum]PMB15
|--S. palmbeachensis Petuch 1994PMB15
|--S. pamlico Petuch 1994PMB15
|--S. perversum (Linnaeus 1758) (see below for synonymy)PMB15
| |--S. p. perversumPMB15
| `--S. p. okeechobeensis Petuch 1994PMB15
|--S. pulleyi (Hollister 1958) [=Busycon (Sinistrofulgur) pulleyi, B. perversum pulleyi]PMB15
|--S. robesonense (Gardner 1948)PMB15
|--S. roseae Petuch 1991PMB15
`--S. yeehaw Petuch 1994PMB15

Busycon carica (Gmelin 1791)BR17 [=Murex caricaBR17, Fulgur caricaPMB15, Pyrula caricaPMB15; incl. *Busycon muricatum Röding 1798KF22]

Busycon carica eliceans (Montfort 1810)PMB15 [=*Fulgur eliceansBR17; incl. Pyrula perversa var. dextra Kiener 1840PMB15]

Sinistrofulgur perversum (Linnaeus 1758) [=Murex perversus, Busycon perversum, Fulgur perversum; incl. F. gibbosum Conrad 1853, Pyrula kieneri Philippi 1848]PMB15

*Sinistrofulgur sinistrum (Hollister 1958) [=Busycon (*Sinistrofulgur) sinistrum; incl. B. (S.) aspinosum Hollister 1958]PBM15

*Type species of generic name indicated

References

[BR05] Bouchet, P., & J.-P. Rocroi. 2005. Classification and nomenclator of gastropod families. Malacologia 47 (1–2): 1–397.

[BR17] Bouchet, P., J.-P. Rocroi, B. Hausdorf, A. Kaim, Y. Kano, A. Nützel, P. Parkhaev, M. Schrödl & E. E. Strong. 2017. Revised classification, nomenclator and typification of gastropod and monoplacophoran families. Malacologia 61 (1–2): 1–526.

[C64] Carpenter, P. P. 1864. Supplementary report on the present state of our knowledge with regard to the Mollusca of the west coast of North America. Report of the British Association for the Advancement of Science 33: 517–686.

Dietl, G. P. 2004. Origins and circumstances of adaptive divergence in whelk feeding behavior. Palaeogeography, Palaeoclimatology, Palaeoecology 208: 279–291.

[KF22] Kantor, Y. I., A. E. Fedosov, A. R. Kosyan, N. Puillandre, P. A. Sorokin, Y. Kano, R. Clark & P. Bouchet. 2022. Molecular phylogeny and revised classification of the Buccinoidea (Neogastropoda). Zoological Journal of the Linnean Society 194 (3): 789–857.

[P12] Petuch, E. J. 2012. Miocene asteroid impacts: proposed effects on the biogeography and extinction patterns of eastern North American gastropods. In: Talent, J. A. (ed.) Earth and Life: Global biodiversity, extinction intervals and biogeographic perturbations through time pp. 967–981. Springer.

[PMB15] Petuch, E. J., R. F. Myers & D. P. Berschauer. 2015. The Living and Fossil Busycon Whelks: Iconic Mollusks of Eastern North America. San Diego Shell Club, Inc.

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