Animal Hands
Different functions of
homologous structures
Many animals share similar body structures. For instance, your nose, a pig’s snout, and an elephant’s trunk can all be called noses. Though these noses have different functions and appearances, all have a similar location and structure. Such similar features are called homologous. Such similar features are called homologous* structures.
: Open X-ray images 01 through 11.
: Briefly examine each image
The x-rays show the hands of the following animals:
Beluga Whale |
Human |
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Macaque Monkey |
Owl |
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Sun Bear |
Zebra |
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Hyena |
Lion |
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Panda |
Sea Lion |
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baboon |
A structure’s shape is often related to its function. A hand used for swimming (a fin) is shaped differently than one used for supporting and animal’s weight as it walks. Likewise, a hand used for flying (a wing) is shaped differently than one used to manipulate objects and use tools.
Examine these x-ray images of animal hands in more detail and compare their structure. Based on the morphology (shape) of each hand, figure out its main function and determine its owner.
1. Use the animal hands (word version) data table to record your observations of the eleven hand x-rays.
: Enhance the features of the animal’s hands. You may want to use some of the following techniques. Refer to the Look-up Tables and Density Slicing IPTechnique Sheets for more details.
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To use this Technique… |
…do this |
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Adjust brightness and contrast |
drag the brightness and
contrast sliders in the Map folder |
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Density Slice |
Options/Density Slice |
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Invert Image |
Edit/Invert |
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Enhance image with filters |
use Process menu items |
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Switch color tables |
Options/Color Tables |
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Adjust Color Tables |
use the ↨ tool in the LUT |
If the image looks worse after enhancing…
Edit/Undo to undo the last thing you did, or
File/Revert to Saved to return to the original image.
2. Briefly describe the main features of each hand. Here are some clues:
§ Does the hand appear to have individual fingers?
§ Does the hand show fingernails or claws?
§ Are the bones thick compared to their length?
§ How many joints does each “finger” have?
§ Can you tell the shape of the flesh covering the bone?
3. In your table, state the function* of each hand
4. Based on the structure and function of each hand, identify the animal shown in each x-ray
Mystery Animal
¿
Open Mystery
Animal
Animals that are closely related have very similar structures. For example, all species of birds have wings, even flightless birds. Because of these similarities, you can figure out what kind of animal a hand belongs to even if you don’t know the exact species.
5. Answer the Data Analysis questions on the data table.
Honors biology (complete on the back of
data table or separate sheet)
Helpful information (diagram of human hand parts)
*Homologous = “agreeing” in Greek
*Functions can include flying, swimming, grasping/manipulating, and walking/running
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File/Open
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File/Close
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Windows/Next
Image to view each of the x-rays.
See the Windows IPTechnique Sheet
for tips on working with several windows open.
HINTS
§ The size of each x-ray is not related to the size of the animal
§ The heavier an animal is, the thicker its bones are. This is a sign that the bones support weight.
§ Macaques and humans are both primates, but macaque hands have more padding for swinging on tree branches.
§ Bird bones are difficult to see in x-rays because they are very thin and light.
§ Pandas appear to have five fingers plus a thumb. This false thumb is an extension of one of their wrist bones. Pandas use it to strip leaves from bamboo, their main food source.
§ Sun bears are small bears. The sun bear has a deformed front paw.
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You may want to look at a picture of each of
these