Practice question

Most amphibians restricted to moist habitats because epidermis extremely thin, moderately keratinized, highly vascularized for cutaneous respiration allowing substantial transepidermal water loss lacking scales, feathers or waterproof lipids impeding desiccation. Mucous film required for oxygen diffusion, excessive evaporation up to several percent body mass per hour risks lethal dehydration. Absence of water-conserving scales or uricotelic adaptations unlike keratinized reptiles amplifies vulnerability. Nocturnal activity, burrowing, proximity to streams and damp leaf litter, dependence on freshwater for breeding reinforces restriction despite being ectothermic cold-blooded.