Chapter 40 - Chapter 40 - Basic Principles of Animal Form...

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Chapter 40 - Basic Principles of Animal Form and Function Chapter 40 Basic Principles of Animal Form and Function Lecture Outline Overview: Diverse Forms, Common Challenges Animals inhabit almost every part of the biosphere. o Despite their great diversity, all animals must solve a common set of problems. o All animals must obtain oxygen, nourish themselves, excrete wastes, and move. Animals of diverse evolutionary histories and varying complexity must solve these general challenges of life. o Consider the long, tongue-like proboscis of a hawk moth, a structural adaptation for feeding. o Recoiled when not in use, the proboscis extends as a straw through which the moth can suck nectar from deep within tube-shaped flowers. Analyzing the hawk moth’s proboscis gives clues about what it does and how it functions. o Anatomy is the study of the structure of an organism. o Physiology is the study of the functions an organism performs. o Natural selection can fit structure to function by selecting, over many generations, the best of the available variations in a population. Searching for food, generating body heat and regulating internal temperature, sensing and responding to environmental stimuli, and all other animal activities require fuel in the form of chemical energy. The concept of bioenergetics—how organisms obtain, process, and use energy resources —is a connecting theme in the comparative study of animals. Concept 40.1 Physical laws and the environment constrain animal size and shape An animal’s size and shape, features often called “body plans” or “designs,” are fundamental aspects of form and function that significantly affect the way an animal interacts with its environment. o The terms plan and design do not mean that animal body forms are products of conscious invention. o The body plan or design of an animal results from a pattern of development programmed by the genome, itself the product of millions of years of evolution due to natural selection. Physical requirements constrain what natural selection can “invent.” An animal such as the mythical winged dragon cannot exist. No animal as large as a dragon could generate enough lift to take off and fly.
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Similarly, the laws of hydrodynamics constrain the shapes that are possible for aquatic organisms that swim very fast. Tunas, sharks, penguins, dolphins, seals, and whales are all fast swimmers. o All have the same basic fusiform shape, tapered at both ends. This shape minimizes drag in water, which is about a thousand times denser than air. The similar forms of speedy fishes, birds, and marine mammals are a consequence of convergent evolution in the face of the universal laws of hydrodynamics. o
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This note was uploaded on 08/23/2011 for the course BIO 101 taught by Professor Taylor during the Spring '11 term at University of West Georgia.

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Chapter 40 - Chapter 40 - Basic Principles of Animal Form...

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