Conclusion

The hydrothermal vent system is a highly heterogeneous environment where chemosynthetic bacteria are the primary producers and the driving force of life. The deep sea shrimp, Rimicaris exoculata, has undergone many evolutionary adaptations to be able to survive such fluctuating conditions on the black smokers that line the Mid Atlantic Ridge. Highly specialised modifications of the shrimp’s morphology have enabled them to harbour epibiotic bacteria that supply the shrimp with the molecules they require to live. Studies have shown that the epibionts are able to directly transfer molecules into the blood of R. exoculata, thus increasing the efficiency of the shrimps feeding. In return for this nutritional gift, R. exoculata provides its epibionts with shelter and actively pursues the optimal location to supply the chemicals the bacteria use for chemosynthesis. The relationship between bacteria and shrimp is truly mutualistic.

The survival of R. exoculata largely depends on their ability to avoid the ever present superheated vent fluid. The variable nature of the mixing zone, that provides optimal conditions for bacteria growth, presents the risk of lethal encounters with high temperature water. The shrimp are able to cope with this threat by producing heat shock proteins that can repair some of the damage suffered from exposure to extreme temperatures. Furthermore, R. exoculata have developed highly sensitive photoreceptors and may have chemosensory abilities that enable the detection and avoidance of the extremely hot vent fluid. This species is able to thrive in vast numbers (>3000 individuals per m-2) in this harsh environment due to its many extraordinary adaptations. These adaptations have been recognised and have resulted in the classification of R. exoculata as a model organism of the extreme hydrothermal vent environment.

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