NATURAL HISTORY OF TURRITELLINE GASTROPODS (CERITHIODEA: TURRITELLIDAE): A STATUS REPORT

A new review of available information, published and unpublished, on the biology and paleobiology of turritelline gastropods expands our knowledge of this important group, which is among the most abundant and widespread marine gastropod clades of the past 130 million years. It also highlights many areas in which additional research is needed. Living turritellines are mainly sessile, semi-infaunal suspension feeders, in shallow waters of full-marine salinity and temperatures below 20 C, but they can occasionally be more active and diverse in their habits, crawling on the surface and thriving in a variety of depths, salinities, and temperatures. They are eaten by a surprising diversity of predators, and infected by numerous parasites, especially trematodes, but little is known about interactions with predators, parasites, competitors, or commensals in nature. Their reproductive patterns (broadcast spawning and spermatophores) appear to depend on high abundance, which may help explain why they are the dominant species in many marine communities. The larvae of most species float (or swim) and feed in the plankton for no more than 2 weeks, but nothing is known about settlement. Several fossils and at least one modern species are brooders. Spermatozoa are dimorphic, and frequently paired and/or multiflagellate. Soft anatomy is known for only a few species, and ranges of variation remain largely undocumented. Radulae in particular have been strangely neglected, and this paper presents only the second published SEM image of a turritelline radula. Shell growth rates are variable but can be relatively rapid. Most species appear to live less than three years. Little is known about shell function or development. Although there is strong evidence for a positive correlation of abundance with available nutrients and/or primary productivity, this has not been examined quantitatively or experimentally. Gathering such natural history information on marine gastropod groups should be as high a priority as systematic and phylogenetic analyses. Information scattered in the literature is now much more available via internet search tools, and this approach should be used for other groups.