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Why are frogs unable to live on some remote oceanic islands?
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frog and toad
The natterjack toad (Bufo calamita) lives in northern Europe.
Frogs are generally unable to inhabit many remote oceanic islands because they have been unable to colonize these isolated landmasses due to the barriers created by salt water.1
Because amphibians have permeable skin, they are highly sensitive to osmotic pressure and the concentration of dissolved salts in their environment. Exposure to the high salinity of the ocean prevents frogs from crossing these bodies of water, as they lack the physiological adaptations necessary to survive in such environments. Consequently, their distribution is limited to areas they can reach without traversing significant saltwater barriers.213