(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11) 		Terebridae
Fasciiolariidae
Columbarium
Conidae
Volutidae
Melongenidae
Colubraridae
Muricidae
Turridae
Muricidae
Harpidae
Figure 1: Neogastropoda Diversity.
IntroductionCharacteristicsPhylogentic RelationshipsReferencesBiosketchesCitations

Introduction

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.