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Basic Principles of Animal Form and Function (ch. 40)
Talons of a hawk
Talons of a hawk


Anatomy and physiology of Life


The anatomy of an organism is the physical biological form of the animal and all the different parts of it. For example, part of a hawk's anatomy are its talons. The physiology of animal is the roles its anatomy play biologically, as in what they accomplish for the organism. An example of physiology is that the talons of a hawk are used to easily grab and incapacitate prey. An easier way of remembering anatomy and physiology is form and function, anatomy being the form and physiology being the function.



The evolution of animal size and shape

Convergent evolution in fast swimmers
Convergent evolution in fast swimmers

An animal's size and shape significantly affect the way an animal lives in and interacts with its environment. Animals have evolved in many different forms in order to survive and pass on their genes most successfully. The evolution of animals is controlled by physical factors such as strength, diffusion, movement, and heat exchange. An example of how the environment can limit an animal's form is for fast-swimming aquatic creatures. If there were any imperfections or bumps on the creature's body, it would cause drag and slow the animal down. This is why animals like seals, penguins, and fish have convergently evolved a streamlined shape. Another example is how an animal's form is regulated is the maximum size of the animal. The bigger it is, generally more structural support, muscle, and energy is also needed. Movement would take more work for a larger animal because it has to move more mass around. In all, the environment and physicals factors of nature will guide the evolution of the animals living in that certain environment.

An animal must exchange materials with its environment



  • Organization of body plans
  • Coordination and control
  • Negative vs. positive feedback
  • Thermoregulation: endothermy, ectothermy, body temperature variation, insulation and circulatory adaptations, evaporative heat loss, behavioral regulation, acclimatization
  • Energy requirements, allocation, and use: metabolic rate, influence of size and activity
  • Energy budgets
  • Energy conservation: torpor and hibernation
physiology