Chapter 40 Basic Principles of Animal Form andFunctionLecture OutlineOverview: Diverse Forms, Common Challenges- Animals inhabit almost every part of the biosphere.- Despite their great diversity, all animals must solve a common set of problems.- 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.- Consider the long, tongue-like proboscis of a hawk moth, a structural adaptation for feeding.- 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.- Anatomy is the study of the structure of an organism.- Physiology is the study of the functions an organism performs.- 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 regulatinginternal 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 themein 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.- The terms plan and design do not mean that animal body forms are products of conscious invention.- The body plan or design of an animal results from a pattern of development programmed by the genome, Lecture Outline for Campbell/Reece Biology, 7th Edition, © Pearson Education, Inc. 40-1itself the product of millions of years of evolution due tonatural 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.- 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.- All have the same basic fusiform shape, tapered at bothends.- 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.- Convergence occurs because natural selection shapes similar adaptations when diverse organisms face the same environmental challenge, such as the resistance of water to fast travel. Body size and shape affect interactions with the environment.- An animal’s size and shape have a direct effect on how the animal exchanges energy and materials with its surroundings.- As a requirement for maintaining the fluid integrity of the plasma membrane of its cells, an animal’s body must be arranged so that all of its living cells are bathed in an aqueous medium.- Exchange with the environment occurs as dissolved substances diffuse and are transported across the plasma membranes between the cells and their aqueous surroundings.- For example, a single-celled protist living in water has asufficient surface area of plasma membrane to service its entire volume of cytoplasm.- Surface-to-volume ratio is one of the physical constraints on the size of single-celled protists.- Multicellular animals are composed of microscopic cells,each with its own plasma membrane that acts as a loading and unloading platform for a modest volume of cytoplasm.Lecture Outline for Campbell/Reece Biology, 7th Edition, © Pearson Education, Inc. 40-2- This only works if all the cells of the animal have accessto a suitable aqueous environment.- For example, a hydra, built as a sac, has a body wall only two cell layers thick.- Because its gastrovascular cavity opens to the exterior, both outer and inner layers of cells are bathed in water.- Another way to maximize exposure to the surrounding medium is to have a flat body.- For instance, a parasitic tapeworm may be several meters long, but because it is very thin, most of its cellsare bathed in the intestinal fluid of the worm’s vertebrate host from which it obtains nutrients.- While two-layered sacs and flat shapes are designs thatput a large surface area in contact with the environment, these solutions do not permit much complexity in internal organization.- Most animals are more complex and are made up of compact masses of cells, producing outer surfaces that are relatively small compared to the animal’s volume.- Most organisms have extensively folded or branched internal surfaces specialized for exchange with the environment.- The circulatory system shuttles material among all the exchange surfaces within the animal.- Although exchange with the environment is a problem for animals whose cells are mostly internal, complex formshave distinct benefits.- A specialized outer covering can protect against predators; large muscles can enable rapid movement; and internal digestive organs can break down food gradually, controlling the release of stored energy.- Because the immediate environment for the cells is the internal body fluid, the animal’s organ systems can control the composition of the solution bathing its cells.- A complex body form is especially well suited to life on land, where the external environment may be variable.Concept 40.2 Animal form and function are correlated at all levels of organization- Life is characterized by hierarchical levels of organization, each with emergent properties.- Animals are multicellular organisms with their specialized cells grouped into tissues.- In most animals, combinations of various tissues make up functional units called organs, and groups of organs work together as organ systems.Lecture Outline for Campbell/Reece Biology, 7th Edition, © Pearson Education, Inc. 40-3- For example, the human digestive system consists of a stomach, small intestine, large intestine, and several other organs, each a composite of different tissues.- Tissues are groups of cells with a common structure and function.- Different types of tissues have