|Figure 1: Neogastropoda Diversity. Some neogastropods are among the most dazzling examples of the diversity that evolution has produced. Sculpturally the Neogastropoda include some of the most extreme shell morphology found in any living group, ranging from the exceedingly long, thin, many-whorled auger snails (family Terebridae, (1)), the amazing spines of some Muricids (family Muricidae, (10)), the elegance of the wonder shell, Thatcheria (family Turridae s.l. (9)), and Syrinx aruanus, the largest living snail that grows to be 1 meter long (family Melongenidae, (6)). The life-style diversity represented is similarly remarkable, ranging from the deadly geography cone that kills 70 % of the people that it stings (family Conidae, (4)) to marine vampires waiting in the shadows of coral reefs to suck blood from fish (family Colubraridae, (7)). The shells of most of the different products of the neogastropod radiation are illustrated; spindle shells (Fasciiolariidae, (2)); pagoda shells, genus Columbarium (3a,b)); volutes (family Volutidae, (5) harp shells (family Harpidae, (11)), and two fossils, a winged muricid (Muricidae, (8)) and a pagoda shell (Columbariidae, (3b). Note the similarity of living and fossil pagoda shells, and the morphological divergence of the Muricids (8 vs. 10). (Photographs by K. S. Matz)|
The Neogastropoda is an order of Gastropoda (Metazoa: Bilateria: Lophotrochozoa: Mollusca: Gastropoda: Caenogastropoda: Sorbeoconcha) comprising >15,000 living species and many thousands of named fossil species ranging back to at least the Aptian-Albian boundary in the early Cretaceous. Living species occur on all kinds of substrates from the highest reaches of the intertidal zone to hadal depths in the ocean; three or four lineages have even penetrated fresh water (Vermeij 2002) (See Figure 1 above for examples). Neogastropods are numerically and taxonomically dominant in many benthic marine environments ranging from the Polar Regions to the tropics; in New Caledonia alone, there may be as many as 3,000 species (mostly still undescribed) in a single group of neogastropods, the turrids (Bouchet 2002). Most neogastropods are predators, many with a range of specialized predation-related adaptations involving the shell, gland secretions, and anatomy of the digestive system (Kantor 1996; 2002; Vermeij 2001; Kawashima 2002; Olivera 2002).
A widely accepted evolutionary scenario for neogastropods envisions three stages: (1) a rapid late Cretaceous (Cenomanian to Campanian) initial diversification (Taylor 1980; Riedel 2000), during which shell morphology remains conservative and few synapomorphies in shell characters emerge; (2) a second diversification during the Paleocene to middle Eocene, when many synapomorphies and most living families emerge; and (3) a third phase of diversification within established families during one or more episodes during the Miocene and Pliocene. Significant extinctions at the end of the Cretaceous, during and at the end of the late Eocene, and to a lesser extent during the Pliocene, punctuate this history.
The assessment of molluscan biodiversity has undergone an unprecedented change with the intensive, comprehensive collection efforts by Bouchet and co-workers at several New Caledonia sites (Bouchet 2002). The most striking discovery was a vast deep-water radiation of one neogastropod group, the turrids (~3,000 species of turrids from New Caledonia alone (Sysoev 2001; Bouchet 2004)!). Preliminary sampling at other Pacific sites has shown surprisingly little overlap with the New Caledonian turrid fauna. Thus, turrids are a dominant component of neogastropod species richness; given the New Caledonian data, the estimate of 10,000 living turrid species worldwide seems conservative. If the trend of little overlap between sites continues, the number may be 2-4x greater. This sector of neogastropod biodiversity is therefore truly uncharted territory, with a majority of deep-water turrid species likely still to be discovered. Since the great majority of turrids are venomous, the Neogastropoda may in fact be one of the largest living orders of venomous animals.
Neogastropods are characterized by at least six anatomical synapomorphies:
(1) Two pairs of salivary glands (true salivary glands and accessory salivary glands)
(2) Dorsal gland (gland of Leiblein or venom gland) in the mid-oesophagus
(3) Valve of Leiblein
(4) Anal gland
(5) Five or fewer radular teeth per transverse row
(6) Lateral and marginal radular teeth oriented backward and lacking a pedunculus
(Ponder 1988; Kantor 2002; Strong 2003)
Discussion of Phylogenetic Relationships
The taxonomy and phylogenetic relationships of neogastropods remain controversial. The number of recognized family-level groups ranges from 15 (Ponder 1988) to 34 or more (Golikov 1988) More than 200 family-group names have been applied to Recent species (Ponder 2005). The taxonomic status of major lineages of neogastropods varies widely; some groups are well defined, such as, the ~1800 species in the family Muricidae (sensu lato) for which a general consensus exists regarding species and genus level taxonomy. However, the Neogastropoda also include the turrids (broadly defined: (Taylor 1993)), a group that comprises >10,000 species that are strikingly different in their taxonomic status- most species have not even been described (Powell 1964; Bouchet 2004)
According to Riedel (2000) and Kantor (2002) the sister group of neogastropods is to be found among carnivorous Sorbeoconcha with a non-derived configuration of the foregut, such as Ficoidea, primitive Tonnoidea, or extinct Pyrofusoidea. The phylogenetic position of the neogastropods relative to other caenogastropods with a siphonal protuberance of the shell and with a proboscis remains a matter of speculation. Also unclear are the relationships among the major groups of neogastropods. As in other large clades, the group is bedeviled with rampant parallel and convergent evolution. Moreover, most of the anatomical data on which phylogenetic scenarios for neogastropods are based come from a single system (the digestive system, especially the foregut) (Kantor 1996; 2002). Further resolution of the phylogeny therefore critically hinges on new sources of evidence from novel molecular markers, the shell, other anatomical structures, and gene families encoding rapidly evolving molecules.
Bouchet, P., Lozouet, P., Maestrati, P., and Heros, V. (2002). "Assessing the magnitude of species richness in tropical marine environments: high numbers of molluscs at a New Caledonia site." Biological Journal of the Linnean Society 75: 421-436.
Bouchet, P., Sysoev, A., Lozouet, P. (2004). "An inordinate fondness for Turrids". Molluscan Megadiversity: Sea, Land, and Freswater. World Congress of Malacology, Perth, Western Australia.
Golikov, A. M. and Starobogatov Y. I. (1988). "Problems of phylogeny and system of the prosobranchiate gastropods." USSR Academy of Sciences. Proceedings of the Zoological Institute 187: 4-77.
Kantor, Y. I. (1996). "Phylogeny and relationships of Neogastropoda". Origin and Evolutionary Radiation of the Mollusca. J. D. Taylor. Oxford: 221-230.
Kantor, Y. I. (2002). "Morphological prerequisites for understanding Neogastropod phylogeny." In (Oliverio & Chemello, eds) Systematics, Phylogeny and Biology of the Neogastropoda. Bollettino Malacologico 38 (Suppl. 4): 161-174
Kawashima, Y., Nagashima, Y., Shiomi, K.(2002). "Toxicity and tetramine contents of salivary glands from carnivorous gastropods." Journal of the Food Hygiene Society of Japan 43: 385-388.
Olivera, B. M. (2002). "Conus venom peptides: reflections from the biology of clades and species". Annual review of Ecology and Systematics, 33 :25-47
Ponder, W. F., & Waren, A (1988). Appendix. Classification of the Caenogastropoda and Heterostropha-A list of the family-group names and higher taxa. Malacological Review Suppl.4: 288-326.
Powell, A. W. B. (1964). "The family Turridae in the Indo-Pacific. Part 1. The subfamily Turrinae." Indo-Pacific Mollusca 1: 227-346.
Riedel, F. (2000). "Ursprung und Evolution der hoheren: Caenogastropoda." Berliner Geowissenschaftliche Abhandlungen, Reihe E 32: 1-240.
Strong, E. E. (2003). "Refining molluscan characters: morphology, character coding, and a phylogeny of the Caenogastropoda." Zoological Journal of the Linnean Society 137: 447-554.
Sysoev, A., Bouchet, P. (2001). "New and uncommon turriform gastropods (Gastropoda: Conoidea) from the South-West Pacific." Tropical Deep-Sea Benthos 22: 271-320.
Taylor, J. D., Morris, N.J., Taylor, C.N. (1980). "Food specialization and the evolution of predatory prosobranch gastropods." Palaeontology 23: 375-409.
Taylor, J. D., Kantor, Y. I. and Sysoev, A. V. (1993). "Foregut anatomy, feeding mechanisms, relationships and classification of the Conoidea (=Toxoglossa) (Gastropoda)." Bulletin of the Natural History Museum, London (Zoology) 59: 125-170.
Vermeij, G. J., Wesselingh, F. P. (2002). "Neogastropod molluscs from the Miocene of western Amazonia, with comments on marin freshwater transitions in molluscs." Journal of Paleontology 76: 265-270.
Vermeij, G. J. (2001). "Innovation and evolution at the edge: origins and fates of gastropods with a labral tooth." Biological Journal of the Linnean Society 72: 461-508.
Baldomero OliveraDistinguished Professor Biology
University of Utah
257 S. 1400 E.
SLC, UT 84112
Research page: http://www.biology.utah.edu/faculty2.php?inum=7
Originally, I was looking for a way to earn a salary while doing something I love - traveling, spending time in the tropics, SCUBA diving, and studying marine snails. Being a marine biologist fit that job description pretty well. The most appealing aspect of science for me now, however, is quite different. I enjoy the intellectual freedom. I am constrained in what I can study by what funding agencies will support. However, within that framework, there is still a lot of room to explore whatever questions I find interesting, and I am only limited by my creativity. That aspect is very rewarding.
Neogastropods are very interesting. They tend to have the most complex shells of any group of mollusks (as well as some of the most beautiful), the most complex behaviors, and the greatest tropical diversity. How did they get that way, and what can this tell us about general evolutionary processes? Fortunately, neogastropods have an excellent fossil record, which means we can study their evolution from a range of independent perspectives (anatomy, molecular DNA, fossil morphology, etc.). Combined, these perspectives should tell us a lot about why and how evolution happens.
As a paleontologist, my primary goal will be to reconstruct the evolutionary history of neogastropods based on their fossil record to better understand the processes driving evolutionary diversification, adaptation, and extinction.
Gregory S. Herbert, Ph.D.Department of Geology
University of South Florida
4202 East Fowler Avenue, SCA 528
Tampa, FL¬ 33620
Research page: http://www.cas.usf.edu/geology/About%20Us/Faculty/herbert/herbert.htm
I cannot remember a time when I wasn't interested in nature. I am and always have been curious about how the world and everything in it works, and I have wanted to understand the fundamental principles. Curiosity and an interest in observing things are the mainstay of my intellectual life.
I was drawn to molluscs for their beauty and ease of observation. Details of these interests and of my life generally can be found in my book, Privileged Hands, A Scientific Life (W. H. Freeman, 1996).
I have long been interested in neogastropods in particular because they exhibit a wide variety of adaptive shell characteristics whose evolution we do not understand very well. Shells as armor, offensive weaponry, aids in locomotion, and in relation to feeding are of particular interest. I have published dozens of taxonomic papers on fossil and living species, and wish to continue my studies of form, function, and phylogeny, with the view to putting these particulars in the general context of biologically driven phenotypic change.
Geerat J. VermeijDistinguished Professor of Geology
Department of Geology
University of California at Davis
One Shields Avenue
Davis, CA¬ 95616
Research Page: http://www.geology.ucdavis.edu/faculty/vermeij.html
Outreach Collaborators:Becky Menlove
Utah Museum of Natural History
Citing this page
B Olivera, G Herbert, G Vermeij, and M Holford. 2006. NeogastropodToL. Version 1 April 2006 http://www.neogastropodtol.org
All images and videos on the www.neogastropodtol.org website are copyrighted and not to be used without written permission from the authors, Olivera, Vermeij, Herbert, or other parties listed for contact.
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Website developed by: Baldomero Olivera, Herbert Gregory, Geerat Vermeij, Mande Holford, Julia Harrison and Jason Briggs.