Feeding

The phenomenon that is the highly specific relationship between bacteria and invertebrates is very common at hydrothermal vents (Hugler et al., 2011). The bacteria are epibiotic, they live on the surface of the host invertebrate, supplying the energy the hosting shrimping needs to survive. These bacteria use a process called chemosynthesis to derive energy from the chemicals that are emitted from the vent chimneys (Van Dover et al., 1988). Many hydrothermal vent species are known to harbour chemosynthic bacteria as their primary source of nutrition such as the giant tube worm (Riftia pachyptila), clams (Calyptogena magnifica) and Bathymodiolus mussels (Van Dover et al., 1988). Though the feeding methods of Rimicaris exoculata has been a topic of much debate (Gebruk et al., 1993). It was originally thought that R. exoculata were heterotrophs, feeding solely on free living microorganisms that inhabit the black smoker chimneys on the Mid Atlantic Ridge (MAR) (Van Dover et al., 1988). The feeding methods of this shrimp were investigated when it became apparent that there was a significant lack of dissolved and particulate food for them to survive (Jannasch, 1985). Expeditions to the MAR site, TAG, discovered that the supply of free living bacteria at this site was not sufficient to meet the trophic demands of the shrimp population (Jannasch, 1985; Gebruk et al., 1993). This discovery provided support for the suggestions that a unique symbiotic relationship had evolved between R. exoculata and chemosynthetic bacteria (Gebruk et al., 1993). It is now known that as well as grazing on free living microbes, R. exoculata have evolved to harbour entire chemosynthetic epibiotic bacteria communities in cavities on their carapace and within their body structure (Gebruk et al., 1993; Petersen et al., 2010; Hugler et al., 2011; Ponsard et al., 2012).

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