Skin Coverings for Vertebrates
Animals have a huge variety of skin coverings. They are different colours and textures, each evolved to suit the animal's habitat and way of life. Many are coloured for camouflage but some have bright colours for display or special designs to startle a predator.
Mammals have hair on their body, which keeps them warm. Mammals are warm blooded which means that they need to keep their body at a constant temperature. Many mammal species grow a thicker coat in winter to keep them warm.
Hair is made of keratin, as are hooves and finger nails. Hair can be different colours but is often brown, for camouflage. The colour and texture changes on different parts of the body. Hairs on top of the body have to protect the animal from the wind and rain.
Birds have feathers all over their skin but usually not on the legs and feet. Feathers are different colours, textures and shapes depending on their function. Without feathers, birds could not fly. Feathers are also important for camouflage and display for males, to win a mate.
Birds are warm blooded too, so the feathers help them to keep warm. (They are so good at keeping the heat in, we often use duck or goose feathers in our duvets or winter jackets!) Feathers are made of keratin, like mammal hair and nails.
Reptile skin is covered in hard, dry scales. These protect the body against knocks and scratches and keeps the body moist inside. Scales are often coloured, for camouflage.
Scales vary in size and shape depending on where they are on the body. The scales underneath the body catch on the rough surface of the ground, creating friction, which helps a snake to move.
Scales are made of keratin like our hair and nails. When reptiles grow, they shed their outer skin, which covers the scales.
Reptiles are cold blooded, so do not need to warm up. Their body temperature just matches the temperature of the surrounding air. Many hibernate in winter, when it becomes too cold.
Amphibians have thin, moist skin, with no hair, scales or feathers. Toads have warts all over their skin. The skin creates a layer of mucous which covers their body and keeps it moist and slippery. The skin is often well camouflaged, in greens and browns.
Amphibians can absorb oxygen and pass carbon dioxide out through the skin, which means they can actually breathe underwater. Water also passes though amphibian skin.
Amphibians are cold blooded. They hibernate in winter, maybe at the bottom of a pond or under a log.
Fish have scales all over their body. The scales overlap, like armour. They protect the fish from the environment and from predators. Some are coloured and many reflect light underwater, to help with camouflage.
Scales make the surface of the body smooth, which helps fish glide through the water. They also prevent the fish from becoming dehydrated, keeping enough water inside their body.
Fish scales are different shapes and sizes in different areas of the body. Fish have a 'lateral line' along the centre of their body. They use this to sense pressure and movement in the water, to avoid capture or to catch their prey. The scales on this line have a gap in the middle.
Let's look at some skin coverings and see if you can identify the animal, they belong to.