Ana Hilario, Ph.D.
Centro de Estudos do Ambiente e do Mar (CESAM)
Universidade de Aveiro, Portugal
BIG WORMS, small worms - Reproduction and Identity
Wednesday – August 29, 2007
Pacific Forum – 3:00 p.m.
Siboglinid tubeworms are ecologically important members of hydrothermal vents, cold seeps and whale carcasses communities. The family Siboglinidae is composed of four groups: Vestimentifera, Frenulata, Monilifera and Osedax. Vestimentifera include, among others, the well-known genera Riftia from hydrothermal vents and Lamellibrachia from cold seeps. Frenulata include, for example, the genera Siboglinum, Polybrachia, and Spirobrachia from cold seeps and sediments enriched in organic matter. Monilifera has only one genus, Sclerolinum, whose species occur in a wide range of habitats, and Osedax inhabits whale carcasses. Ever since the discovery of vestimentiferans in 1977, researchers have puzzled over how siboglinids colonize habitats that are highly ephemeral, unstable and sometimes spaced hundred of kilometres apart. Because they are keystone species in eastern Pacific hydrothermal vent habitats and in Pacific and Caribbean seeps vestimentiferans have been, in general, better studied. Microscopy analysis, and in situ and in vitro experiments have shown that female vestimentiferans fertilize their eggs internally and release the resulting embryos at an early developmental stage, optimizing their chances for survival and long-distance dispersal. The discovery of a high diversity of frenulate species in mud volcanoes in the Gulf of Cadiz, and the possibility to explore these habitats through several European research programs is an excellent opportunity to extend our knowledge on this understudied group of siboglinids. Due to their small size and difficulty of retrieving the animals from their tubes, molecular tools have proved essential to the identification of species. From the 8 species found so far at least 2 are new to science, one being from a new genus. The diversity, distribution and reproductive biology of these species is being studied in parallel with colonization experiments deployed in selected mud volcanoes in the Gulf of Cadiz and in the Nordic Margin.