Animal Coverings - fur, feathers and scales.
Teacher's notes
Introduction
Vertebrate Skin Coverings
Protection
Insulation
Other Functions
Animal Groups and their coverings
Teacher's notes
Education staff at Wellington Zoo are available to help with planning a study unit to suit your students' needs and can provide you with further resources on this topic
This unit contains resource material suitable for Living World Levels 1 - 3.
Level 1:1
Group the living world according to some of its attributes.
Level 1:2
Observe and identify parts of common animals.
Level 2:1
Use differences and similarities in external characteristics to distinguish broad groups of living things.
Level 2:2
Investigate and understand the general functions of the main parts of animals.
Level 3:1
Distinguish between living things within broad groups on the basis of differences established by investigating external characteristics.
Level 3:2
Investigate special features of common animals and describe how these help to stay alive.
Introduction
This unit is designed for teachers as an introduction to animal classification and the study of adaptive features. At Wellington Zoo most of the animals on display belong to a group called vertebrates. All vertebrates possess an internal skeleton made up of bones and, in particular, they have a backbone or spine made up of a series of bones called vertebrae. Vertebrate animals include the largest and most familiar animals but account for less than 3% of the different types of animal in existence today.
Vertebrate Skin Coverings
It is possible to classify (group) vertebrate animals into 5 groups based on easily observed features like parts of the body, skin covering, or birth of their young. One of the easiest features to observe is the skin covering of the animal:
- fish are covered with wet scales
- amphibians have naked skins
- reptiles are covered with dry scales
- birds have a body covering of feathers
- mammals have a covering of hair (fur)
Why have skin coverings?
The skin of vertebrates is a vital organ system. It provides protection for the tissues beneath it and acts as a sensory information system for the animal to register environmental changes. The outer surface layer of vertebrates is mainly composed of structures formed from the insoluble protein keratin. This tough chemical may be found in a number of forms (scales, feathers, hair, claws, nails, hooves, antlers) and provides an extra barrier between the internal tissues of the animal and the environment.
Protection
Skin coverings provide a protective layer to the skin against physical damage as well as acting as a barrier to disease organisms like fungi and bacteria.
Reptiles are dependent upon their covering of overlapping scales to reduce evaporation of body water when they are in dry environments.
Insulation
Feathers and fur form an insulating cover for the warm-blooded vertebrates (birds and mammals), helping these animals retain their body heat.
Other Functions
Other functions associated with some skin coverings include:
- camouflage for protection against predators
- recognition signal to mates or members of the same population
- flight (contour feathers)
- sensory organs (whiskers)
- protection against harmful UV rays from the sun
- waterproofing
Animal Groups and their coverings
Fish
Fish are covered in a flexible layer of overlapping scales that are embedded in the inner layer of the skin. They are also protected by a layer of mucous slime that is secreted from glands in the skin. This slime layer is antiseptic and helps to lubricate the animal, making it more streamlined when swimming.
Sharks and Manta rays have a different type of skin scale from most fish. They are small and tooth-like. The scales extend into their mouth where they serve as teeth.
Amphibians
Most amphibians have naked skins that lack scales, feathers or fur, but the outer layer of the skin may be tough and horny. Their skin contains many mucous glands that secrete slime to lubricate the skin and prevent waterlogging.
As the skin of many amphibians is also an organ of respiration, it must be kept moist.
Reptiles
The reptile skin contains no sweat glands and the animals are subject to drying out if they are in an exposed environment. They possess a protective layer of horny scales that helps prevent water loss from their body. In most reptiles, the outer layer of their skin is periodically renewed and the old layer is shed.
Mammals
Mammals are the only animals that possess hair, a structure that grows from the outer layer of the skin. A dense soft covering of hair may be called fur or wool. Hair forms an insulating cover. Glands in the mammalian skin release oils which help to keep the fur waterproof and offer protection against rain and the cold.
Some mammals do not need the protection of a furry coat:
- elephants, rhinos and hippos have only a sparse covering of hair over their thick, leathery skins
- whales and dolphins contain an insulative layer of blubber under their skin, but still possess a few sensory bristle hairs around their mouths.
Birds
Birds possess a covering of feathers on their body and scales over the exposed skin of their legs.
Feathers are specialised structures of keratin and occur in 3 types:
- down feathers provide a protective insulation layer
- filoplume feathers are hair-like feathers associated with down feathers
- contour feathers provide an aerofoil plane surface for flight.
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