Organisms and their environment: Adaptations of organisms

Structural Adaptations


All organisms have adaptations - traits or characteristics - that help them to survive and reproduce in a particular habitat.

PolarBear.jpgshark.jpg

Structural adaptations are physical features of an organism, such as shape, colour, size. Not every physical trait of an organism, or every use of a trait by an organism, is an adaptation, however.


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A comparison of the skeletal structure of an elephant and blue whale.
For the aquatic mammal, the buoyant affect of water tends to offset the affect of gravity. As a result, the whale requires less structural support than the elephant, despite its massive size.


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Cacti have fleshy leaves, for water storage and spines for defence and to reduce water loss.

Adaptation animation

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Big Idea – Structural Adaptations
What you intend the students to learn about this idea?
· Different examples of structural adaptations in plants and animals in differing environments

Adaptations of animals for desert survival



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  • Transparent fur
  • Thick, oily coat
  • Blubber
  • Small ears and tail
  • Black skin
  • Paws – broad, bumpy
  • Sharp, curved claws

· How structural adaptations aid in the survival of an organism in their environment.

Video on Polar Bear Structural Adaptations for Survival
http://videos.howstuffworks.com/hsw/23290-the-ultimate-guide-to-bears-adaptation-and-survival-video.htm

Plants have structures to reduce water loss, in environments where water is scarce:
  • Stomata – closing, opening at night, fewer or sunken
  • Waxy cuticle – non-porous
  • Small leaves – smaller surface area
  • Thick, fleshy leaves – stores water - succulents

· How organisms evolved structural adaptations ie mutation, variation.
  • Variation - differences between individuals within a population.
  • Mutation - random and unpredictable change in chromosomal DNA.

Genetic viariability in a population originates through mutations.


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Variation in colour and banding patterns in a single species of tropical tree snail.





· Homology and Analogy – similar structures with differing functions/different structures that have similar functions.
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homologous vs analogous structures

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Homologous structures



Why is it important for students to know this.
· Help understand key concepts involved in the process of natural selection
· Understand the role variation and mutation play in adaptation
· Understand how organisms relate to their environment
· Consider how structural adaptations can be used to gauge environmental impact
· Consider the possible implications for the future
What else you know about this idea (that you do not intend students to know yet)
· Morphology
· Adaptive radiation
· Divergent and Convergent evolution
· Phenotypic plasticity
Difficulties/limitations connected with teaching this idea
· Teaching the students that adaptations are not a conscious, directed method of survival ie an organism cannot choose to adapt in order to ensure its survival
· Student's understanding of key concepts and terms
· Students may not be aware of time frame involved with the evolution of adaptive traits
· Students may struggle with the concept that adaptation works for the survival of an individual, not as a species or population
Knowledge about students’ thinking which influences your teaching of this idea
· Students alternate conceptions tend suggest a Lamarckian view
· Students should have a prior understanding of key concepts and terms, but may not be able to apply them accurately
· Students belief that survival of a species suggests that adaptation benefits species as a whole, rather than the individual which then goes on to reproduce
Other factors that influence your teaching of this idea
· Challenge students misconceptions and preconceptions about the evolutionary process leading to structural adaptations
· Assist students to develop their observational and analytical skills to be able to apply knowledge and draw conclusions themselves
Teaching procedures (and particular reasons for using these to engage with this idea)

Activities


  • Students are provided with an image of a shark, cheetah, bilby and an elephant. Working individually students are to note down the structural adaptations for each animal, the functions of each adaptation and how it aids in the organism's survival. As a class discuss what adaptations were noted, ask them to infer what type of ecosystem each species inhabits, and how these structures benefit survival.

  • Students are posed questions about plant structures, prompted by visual examples;
    • Why would a thick leaf lose water slower than a thin leaf?
    • Why would a leaf with stomata on the underside of its leaf lose water slower than a leaf with the stomata on the top?
    • Why would a leaf covered with trichomes have a lower rate of water loss?
    • Why would plants with recessed stomata have a lower rate of water loss?
    • Why does plant shape and reduction in leaf size reduce water loss?

  • Set Questions. Students to complete as much as possible before using external references:
  1. What is the purpose of the mane on a male lion?
  2. Why are the eyes of a lion set in the front of its head rather than on the sides?
  3. A lion has heavily muscled forelimbs and shoulders. Why?
  4. Why do they have forepaws equipped with long, retractile claws?
  5. Why do they have a rough tongue?
  6. How are the hands of a koala adapted for life in a tree?
  7. How are the heads of vultures adapted to what they eat?
  8. Why do many monkeys and apes have long arms?
  9. Describe special adaptations on the hands of gibbons.
  10. Sea otters spend almost their entire lives in water. How is their fur adapted to keep them warm?
  11. Why is it a critical situation when otters encounter oil spills?
  12. Besides having stiff spines that stick out from their bodies and help protect them, African hedgehogs also have loose skin under those spines and powerful back muscles. Why?

  • Practical - Skeletal variation in vertebrates.



  • Activity - Bird Beaks and Feet: predict feeding habits and habitats



· Visual representations and examples of animal and plant structural adaptations, including images and specimens. Students are given an example and are then to identify and conclude adaptive traits, and how they aid in survival. Students learn to successfully identify structures through their own learning and continue to draw conclusions by cognitive learning. Images and specimens are effective for those students that learn visually and kinaesthetically. Cognitive learning allows students to see the relevance of the knowledge presented as well as effectively learn the information, opposed to memorising theoretic concepts
· Class discussions allows students to be engaged in their own learning and allows the teacher to identify and correct alternate conceptions and key areas students find difficult to understand
· Video and animation of the processes involved in natural selection, how structural traits impact and influence survival and how organisms are adapted to their environment. Engaging and concise form of conveying information
· Worksheet, activities – questioning various forms of structural traits, identifying what environment they exist in and how it aids in survival.
Specific ways of ascertaining students’ understanding or confusion around this idea (include likely range of responses)
· Class discussion – while not all students will actively participate, it will allow the class to actively work towards their own learning. Allows the teacher to gauge areas students are struggling with. It is expected that where students fail to respond the area needs further clarification. It is also expected that if one student fails to correctly answer other students are likely to have the same conclusion.
· Assessment – set questions and a test – a variation of questions will ascertain where students are failing to understand concepts or apply knowledge.
· Group activities – most students will be able to identify or differentiate structural adaptations, but may struggle with the process or how it aids in individual survival of an organism

References
Collins, D; Semple, A; Carter, M; Cleeland, C (2000) Nelson Biology, Nelson Thomson Learning, Australia
Freeman, S & Herron, J.C (2004) Evolutionary Analysis, (third edition), Pearson Education, Upper Saddle River, NJ
Kinnear, J & Martin, M (2006). Nature of Biology Book 1, (third edition), Jacaranda Press, Australia
Victorian Curriculum Assessment Authority (VCAA) VCE Biology Study design (2006-2010) http://www.vcaa.vic.edu.au/vce/studies/biology/biologyindex.html