Final answer:
Halophilic bacteria like Halobacterium salinarum and Haloferax volcanii are the most likely to survive in seawater exposed to the sun's heat when tide goes out, due to their adaptations for high salt and temperature conditions. They thrive in hypersaline environments, performing photosynthesis with bacteriorhodopsin, giving them a purple color in large blooms.
Step-by-step explanation:
The bacteria most likely to survive in seawater that is exposed to the heat of the sun when the tide goes out are halophilic bacteria such as Halobacterium salinarum, Haloferax volcanii, and other related species. These organisms are adapted to high salt concentrations, with some even requiring environments with a sodium chloride concentration close to saturation, which is found in bodies of water such as the Dead Sea and certain lakes in Antarctica and south-central Asia. Characteristics that enable these bacteria to thrive include high intracellular concentrations of K* and glycerol, active pumping out of salt ions, and proteins that function optimally at high salt concentrations.
Haloferax volcanii, for instance, possesses a sophisticated system of ion exchange that allows it to balance salt concentrations even at high temperatures. Moreover, halobacteria can perform photosynthesis through the protein bacteriorhodopsin, making them stand out with a distinct purple color visible in large blooms. Such adaptations allow these bacteria not only to survive but also to flourish under the harsh conditions of high salinity and temperature fluctuations.