About the Cover.

Abstract

Listen

Translate article

Next article FreeAbout the CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCoverThe illustration shows a juvenile Conus ebraeus foraging at night at a snail's pace on reef rock covered with a thin layer of sand and green algae, in Pago Bay, Guam. The front end of the foot (black, edged with pale red) is visible against the substrate at the right, as is the posterior end at the left. The long black siphon extending from the anterior end of the shell parallel to the substrate directs a stream of water into the mantle cavity, bringing oxygen to the gill for respiration and past a large chemoreceptor, the osphradium. During food seeking, the siphon swings from side to side, the osphradium receives chemical stimuli emanating from potential food and transmits this information to the brain, and the snail directs its movement toward the prey. Conus uses hollow, pointed radular teeth as hypodermic needles to inject neurotoxic venom into a victim that is quickly paralyzed and swallowed whole. C. ebraeus may have the broadest distribution of all benthic marine animals, ranging from the Red Sea across the tropical Indian and Pacific Oceans to Central America. Until the study by Thomas Duda, Alan Kohn, and Amber Matheny in this issue (pp. 292–305), it was considered one of more than 500 species in the hyperdiverse genus Conus. These species typically exhibit fixed differences in shell shape and color patterns that are sufficient to distinguish them. Genetic structure in C. ebraeus populations is minimal across much of its range,1 but mitochondrial and nuclear gene sequences revealed some specimens from Okinawa sufficiently distinct to suggest the presence of a second, cryptic species. Further investigation showed this species to co-occur with true C. ebraeus at Okinawa. Although the two species could not be distinguished by shell characters, study of radular tooth morphology showed striking differences, and these correlated exactly with the molecular distinctions. Conus species with different radular tooth sizes and shapes typically attack members of different prey taxa. Adult C. ebraeus prey exclusively on errant polychaetes of the families Nereididae and Eunicidae, but the cryptic second species discovered in this study eats mainly sedentary polychaetes of the family Capitellidae. Moreover, unlike most cryptic species discovered by genetic differences, this one was named and described in 1895. Rudolph Bergh described Conus judaeus after dissecting a single specimen whose radular teeth differed markedly from those of C. ebraeus, but whose shell and other internal anatomy were indistinguishable. Long synonymized as a freak C. ebraeus, C. judaeus, whose teeth are identical to those of the cryptic species and distinct from all other known Conus species, is now concluded to be a valid species. Additional heretofore unrecognized cryptic species likely exist in this and other species-rich marine genera, and their future discovery may profoundly affect our understanding of marine biodiversity. Photo credit: Thomas F. Duda, Jr., University of Michigan. Cover layout: Beth Liles, Marine Biological Laboratory. Next article DetailsFiguresReferencesCited by The Biological Bulletin Volume 217, Number 3December 2009 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/BBLv217n3cover Views: 199Total views on this site © 2009 by Marine Biological Laboratory. All rights reserved.PDF download Crossref reports no articles citing this article.