The Adaptation in fish that has increased their surface area to volume ratio is : Fins
The presence of fins in fishes has increased the surface area to volume ratio of fishes( SA:V ). Given that the surface to volume ratio of large organisms such as fishes are not large enough for efficient diffusion. therefore the adaptation of fins has helped to increase the surface area to volume ratio.
Hence we can conclude that The Adaptation in fish that has increased their surface area to volume ratio is : Fins
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