| Comparative Anatomy
Shown below are images of the skeletal structure of the front limbs of 6 animals: human, crocodile, whale, cat, bird, and bat. Each animal has a similar set of bones. Color code each of the bones according to this key:
Humerus [ ]
Ulna [ ]
Radius [ ]
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Carpals [ ]
Metacarpals [ ]
Phalanges [ ]
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For each animal, indicate what type of movement each limb is responsible for.
Animal
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Primary Functions
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Human
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Using tools, picking up and holding objects
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Whale
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Swimming.
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Cat
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Running, jumping, pouncing, climbing, catching prey.
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Bat
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Flying, gliding.
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Bird
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Flying, gliding.
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Crocodile
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Swimming, walking.
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Compare the skeletal structure of each limb to the human arm. Relate the differences you see in form to the differences in function.
Animal
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Comparison to Human Arm in Form
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Comparison to Human Arm in Function
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Whale
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Whale has a much shorter and thicker humerus, radius, and ulna. Much longer metacarpals. Thumb has been shortened to a stub.
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The whale fin needs to be longer to help in movement through water. Thumbs are not necessary as the fins are not used for grasping.
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Cat
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Cats walk on what would be the toes for humans. Their fifth metacarpal and phalage (thumb) is very reduced. They have a retractable claw.
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Cats are designed to be ambush predators. They can run much faster, climb, and pounce.
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Bat
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The metacarpals and phalanges of bats are much, much longer, narrower, and lighter. There is a webbing of skin between each digit.
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Bats are capable of flight.
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Bird
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The metacarpals and phalanges of birds are very heavily modified, actually coming to a single point at the end of the limb.
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Birds are also capable of flight, but in a much more advanced way than bats. They generally have more control, are capable of faster speeds,
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Crocodile
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The arm bones are shorter and thicker. The middle three digits are much longer than the other two.
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Crocodiles are built much closer to the ground, and spend a good deal of time swimming.
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Compare the anatomy of the butterfly and bird wing below.
1. What is the function of each of these structures?
Flight.
2. How are they different in form? Give specific differences.
The bird wing is constructed of bone, muscle, skin, and feathers. The butterfly wing is a thin membrane of exoskeleton inflated by blood.
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