Animal Groups
Teacher's notes
Introduction
Living or non-living
Living or dead
Features of animals
Classification
Naming animals
Two main groups of animal
Five vertebrate groups
Warm-blooded and cold-blooded
Invertebrate groups
Three mammal groups
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 page contains resource material suitable for Living World Levels 1, 2 & 3, supported by the worksheets listed on the right of the page:
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.
Introduction
Nearly 2 million different kinds of animals have been described, but millions more are awaiting identification. Some scientists believe that the total number of animals may be as high as 30 million. Scientists group or classify animals based on features they have in common with each other.
The information below contains information on animal classification and refers to the major groups of animals held at Wellington Zoo.
Living or Non-living
Most people can tell if an object is living or not, based on features such as whether it moves, breathes or grows. For some objects - e.g., a sponge in the ocean, a pumpkin seed or a virus - it is not so easyobvious to determine whether they are alive or inanimate. Biologists have decided that an object is living if it carries out the following 8 functions:
- Movement: all or part of the living object can move
- Respiration: living things obtain energy from food during respiration
- Sense the environment: living things respond to changes in their environment
- Circulation: living things circulate gases and other chemicals
- Growth: living things grow
- Reproduction: living things produce new offspring
- Excretion: living things are able to get rid of waste products from their bodies
- Nutrition: living things can make their own food or obtain it by eating other living or once-living (dead) things.
The functions can be remembered by the following mnemonic Mrs C. Gren.
Living or Dead
Living things are called organisms. Dead organisms no longer carry out any of the life functions, but, because they were once alive, they are classified as part of the living world. In contrast, objects or items like robots, aeroplanes, or fire are inanimate or non-living, because although they can move, sense the environment or grow, they do not and never have carried out all 8 life functions.
Features of Animals
- Animals have bodies made up of many cells (multicellular).
- Animals ingest food (consumers).
- Animals have nerves and muscles for responding to the environment.
- Animals can move all or part of their bodies.
Classification
Biologists sort organisms into groups to make sense of the tremendous variety of life that is present on Earth. The groups are organised in a hierarchical system that shows how the organisms are related to each other.
The basic unit of classification is the species. Organisms that share many features in common and can breed with each other and produce fertile offspring are members of the same species. Related species are grouped into a genus (plural genera). Genera are grouped into families; related families into orders; related orders into a class; related classes into a phylum (plural phyla); and related phyla into a kingdom. Kingdoms are very large groups, embracing millions of kinds of organisms. Most biologists recognise 5 different kingdoms (although other schemes of classification exist). All animal groups belong to the Animal Kingdom.
Naming Animals
All described organisms are given a two-word scientific name. The first part of the name is the genus to which the organism belongs and the second part is the species name. The scientific name of the North Island brown kiwi is Apteryx haastii. The genus Apteryx contains other species of kiwi that are given a different second part to their name.
Two Main Groups of Animal
Most of the world's large and familiar animals belong to a group of animals called vertebrates. All vertebrate animals possess an internal skeleton made of bones, and in particular they have a backbone or spine made up of a series of bones called vertebrae. Vertebrates make up less than 3% of the world's animals.
Most animals are invertebrates. They do not have a bony skeleton inside their bodies. Some like insects, spiders and crabs have a hard outer shell (exoskeleton) which provides support and protection for the soft body inside.
Five Vertebrate Groups
Vertebrates are grouped into 5 classes based on features of their body structure, mode of reproduction and internal physiology. All classes are represented at Wellington Zoo, although only one or two types of fish and amphibian are present. Young students should be able to sort vertebrates into the 5 classes based on easily observable features like skin covering, type of limb and habitat.
A useful mnemonic to remember these groups and their evolutionary order is FARM Birds.
Fish
- live in water
- breathe with gills
- have skin covered with scales
- have fins
- lay soft eggs
- are cold-blooded.
Amphibians
- the young live in water, adults live on land
- the young breathe with gills, adults breathe with lungs
- have moist, scale-less skin
- have 4 legs
- lay soft eggs
- are cold-blooded.
Reptiles
- mainly live on the land
- breathe with lungs
- have scaly skin
- have 4 limbs or no0 limbs (snakes)
- lay eggs with leathery shells
- are cold-blooded.
Mammals
- mainly live on land
- breathe with lungs
- have fur or hair covering their body
- most have 4 legs, or 2 legs and 2 arms
- give birth to live young (monotremes are an exception)
- feed their young on milk produced by mammary glands
- are warm-blooded.
Birds
- live on the land
- breathe with lungs
- have feathers covering their body
- have 2 legs and 2 wings
- most can fly
- lay eggs with hard shells
- are warm-blooded.
Warm-blooded and Cold-blooded
The terms warm-blooded and cold-blooded refer to the ways animals maintain their internal body temperature. Cold-blooded or ectothermic animals cannot regulate their body temperature directly; it is determined by the temperature of their surroundings. Warm-blooded or endothermic animals are able to generate their own heat and can maintain a constant internal temperature.
Invertebrate Groups
More than 30 phyla are included in the invertebrates. They encompass a wide variety of body form and size. Included among them are sponges, jellyfish, worms, molluscs (snails, shellfish, slugs), starfishes and arthropods (insects, spiders, millipedes, crustaceans). Many invertebrate groups inhabit the oceans, although the most successful animal group on Earth, the insects, is land-dwelling.
Half of the described animals in the world are insects (over 1 million named), and there are estimates that up to another 10 million types of insect await discovery and identification. The only invertebrate held at Wellington Zoo is the Wellington tree weta, a native insect.
Three Mammal Groups
Monotremes are a very small group comprising 3 species of primitive egg-laying mammals found in Australia and New Guinea: the platypus and 2 species of echidna. Their young are fed on milk that exudes from the mother's milk glands. They are not represented at Wellington Zoo.
Marsupials are a group of mammals that survive mainly in Australia and South America. They give birth to live young at a very early stage of their development. For some months after birth the young animal continues to develop and grow in a special pouch on the mother where it can feed from her milk glands. Wallabies and kangaroos are the marsupials represented at Wellington Zoo.
Placentals are the main group of mammals to which humans, cats, whales, bats and sheep belong. The young are born well developed, after receiving nutrition from the placenta in the mother's uterus. Following birth, the young are nourished by milk.
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