Epibiotic bacteria associated with the recently discovered Yeti crab, Kiwa hirsuta

Abstract

The Yeti crab, Kiwa hirsuta Macpherson et al., is the single known species in a recently discovered crab family Kiwaidae (Decapoda: Galatheoidea) from deep-sea hydrothermal vents. Its chelipeds, walking legs and the ventral surface of its cephalothorax are covered with dense setae that, in turn, are covered with clusters of filamentous bacteria, making the crab appear extraordinarily 'hairy'. Electron microscopy revealed dense bacterial clusters attached to the chitinous outer layer of the setae. Molecular phylogenetic analyses revealed the setae-associated bacteria to be dominated by epsilon-Proteobacteria ( approximately 56% of the recovered ribotypes), gamma-Proteobacteria ( approximately 25%) and Bacteroidetes ( approximately 10%). Fluorescence in situ microscopy confirmed the attachment of filamentous epsilon-Proteobacteria on setae, but no specialized morphological structures appeared to exist for bacterial attachment. Key enzymes involved in the reductive tricarboxylic acid cycle (ATP-dependent citrate lyase) and sulfite oxidation or dissimilatory sulfate reduction (bidirectional APS reductase) were detected. Consequently, the potential for carbon fixation and cycling of reduced and oxidized sulfur appear to exist in the dense microflora that grows on the crab's setae.

Molecular taxonomy and naming of five cryptic species ofAlviniconchasnails (Gastropoda: Abyssochrysoidea) from hydrothermal vents

“…2.4 Alviniconcha aff. hessleri (Goffredi, Jones, Ehrlich, Springer, & Vrijenhoek, 2008;Okutani et al, 2004;Sievert et al, 2008;Suzuki et al, 2005a;Suzuki et al, 2005b;Suzuki et al, 2009) Alviniconcha sp. Indian Ocean.…”

Inorganic carbon fixation by chemosynthetic ectosymbionts and nutritional transfers to the hydrothermal vent host-shrimp Rimicaris exoculata

“…Among the Crustacea, chemosynthetic epibioses are reported in only a few hydrothermal decapods: the shrimp Rimicaris exoculata (Segonzac et al, 1993), the galatheid crabs Kiwa hirsuta (Macpherson et al, 2005;Goffredi et al, 2008), Kiwa puravida (Thurber et al, 2011), and Shinkaia crosnieri (Miyake et al, 2007), and two amphipods from littoral sediments (Gillan and Dubilier, 2004; and sulphide-rich caves (Dattagupta et al, 2009). Most of these associations are regarded as nutritional ectosymbioses, but to date, there is little direct evidence of bacterial autotrophy and no direct demonstration of mutualistic nutritional bacteriahost interactions.…”

Molecular evidence of digestion and absorption of epibiotic bacterial community by deep-sea crab Shinkaia crosnieri

“…In addition, several species of deep-sea vent invertebrates harbour bacteria (epibionts) that colonize the surfaces of specialized tissues such as the dorsal setae of the polychaete Alvinella pompejana, the gill chambers of the shrimp Rimicaris exoculata and the setae of the galatheid crabs Shinkaia crosnieri, Kiwa hirsuta and K. puravida (Polz and Cavanaugh, 1995;Cary et al, 1997;Goffredi et al, 2008;Watsuji et al, 2010;Thurber et al, 2011). The epibiotic microbial communities associated with these hosts are believed to have chemolithoautotrophic and methanotrophic products that support their hosts nutritionally, as well as the endosymbionts themselves (Goffredi et al, 2008;Grzymski et al, 2008;Watsuji et al, 2010;Thurber et al, 2011;Ponsard et al, 2012). Radioisotope-labelled tracer experiments suggest that R. exoculata epibionts achieve chemolithoautotrophic production by oxidizing reduced sulphur compounds and ferrous iron (Ponsard et al, 2012).…”