Animals
Introduction
Key concepts
The activities in this topic are designed to explore the following key concepts:
- The scientific definition of 'animals' is that they are organisms that ingest food for survival. They are 'consumers' in contrast to plants which are 'producers', building and storing material through the photosynthetic process.
Structure, function, adaptation
- Animals have various 'structures' that enable them to survive: skeletal structures for support; limbs and jaws for ingesting and collecting food; structures for movement and defence; structures for flight or predation; structures for digestion and respiration; and structures for reproduction. Each organism has particular forms of these structures that are essentially solutions to the survival 'problem'.
- Organisms' structures and behaviours should be viewed in terms of their survival purposes. Students should be supported to take this view.
- Each animal is adapted to a particular ecological niche, which involves interdependence with other living organisms as well as dependence on non-biotic factors.
Animal behaviour
- Animal behaviour must also be understood in terms of its adaptive function. Animals behave in ways that maximise their survival chances.
- Each species has unique behaviours that can be studied using a range of techniques.
Teaching note: For schools, it is most
fruitful to study the behaviour of simpler life forms since their behaviour
is not so complex and students are less likely to anthropomorphise.
Animal life cycles
- Some animals change from one form to another during their life cycle.
- Each type of animal has its own life cycle.
- Even during stages at which the animal appears inactive, the animal is alive.
- The changes in the life cycle of an animal have specific environmental requirements.
- Some animals, once they hatch, have the same form for the remainder of the life cycle.
Teaching note: Life cycles should really
be called 'reproductive cycles'. In animals and plants, life cycles have
unique details that are adaptive to the particular environment, including
the number of offspring (or seeds) and the timing, frequency and mechanisms
of reproduction.
In animals, the reproductive cycle can coincide with the life cycle of an organism if the adult dies after fertilisation (as with butterflies, and also some mammals, such as the male antechinus). However, most animals will go through many reproductive cycles in a lifetime.
Students' alternative conceptions of animals
Research into students' ideas about this topic has identified the following non-scientific conceptions:
- Students (and adults) will often associate the category 'animal' with mammals only, and not include insects, fish, etcetera.
- Students will tend to think of organisms only interacting with the physical environment and plants, without appreciating the complex interdependence of species.
- Younger students will have a view that animal structures are chosen by animals for adaptive purposes, and could be changed if the environment was altered. Thus, a snow leopard actively decides to be white as a camouflage strategy.
- Students will often view 'adaptation' as a short-term individual response, like suntanning over summer, rather than in terms of species survival.
- Younger students tend to think of animals as individual rather than focusing on populations or interactions.
- Younger students interpret animal behaviour in psychological terms (the spider is scared, the rabbit likes to live in burrows, the bird protecting its nest is angry), rather than seeing it as adaptive.
- Students will not appreciate that life-cycle diagrams are simplistic models that take no account of numbers of offspring and mortality, ongoing life of an adult animal, adaptive aspects of seasonal timing, etcetera.
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17th November 2008