Grey wolves have long embodied the spirit of the wilderness. Once they had the largest natural distribution of any mammal except humans. Sadly, they can no longer claim this record as they have been lost from much of their former lands. Grey wolves still occupy a range of habitats including Arctic tundra, prairies and forests.
Although melanin is found in the skin of many species, in the reptiles, the amphibians, and fish, the epidermis is often relatively colourless. Instead, the colour of the skin is largely due to chromatophores in the dermis, which, in addition to melanin, may contain guanine or carotenoid pigments.kin of a different nature exists in amphibians, reptiles, and birds. All mammals have some hair on their skin, even marine mammals which appear to be hairless. The skin interfaces with the environment and is the first line of defense from external factors.
Some  amphibians have a rough leathery skin.  Reptiles are generally bigger in size than amphibians.  Reptiles include four groups of animals-lizards and snakes,  turtles and tortoises, crocodilians, and tuatara. Amphibians  include three groups of animals-frogs and toads, salamanders and  caecillians. Different species of reptiles live on land, in water, or both  on land and in water. However, all amphibians are born in water and  spend early part of their lives in water in form of larvae. Through  a process of metamorphosis the larvae of amphibians grow into  adults which are quite different from the larvae.