Chapter 21 - Introduction A Feeding(ingesting food is a...

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Chapter 21 Lecture Outline Introduction Getting Their Fill of Krill A. Feeding (ingesting food) is a distinctive characteristic of the animal kingdom. B. The humpback whale, from an unusual habitat, shows how an animal’s structure and behavior are directly tied to feeding and food processing. 1. Humpback whales are suspension feeders that strain small fish and crustaceans from the ocean. A 72-ton whale processes as much as 2 tons of food a day. 2. These whales use “bubble nets” to help concentrate their food at the surface. The mouth has a tremendous volume when expanded and uses the brushlike baleen to sift the food from the water. The stomach can hold up to half a ton of food at a time. 3. For four months in the summer, these whales feed in the rich, cold oceans of polar regions and store up vast fat reserves. In the winter, they migrate to warm, southern oceans to breed. They eat little for eight months until they return to the polar regions. I. Obtaining and Processing Food Module 21.1 Animals ingest their food in a variety of ways. A. All animals eat other organisms. Eating can be by absorption (as in a few parasitic worms) or by ingestion. B. Animals can be classified into one of three dietary categorized. 1. Herbivores (e.g., deer or sea urchins) eat plants or algae. 2. Carnivores (e.g., lions and spiders) eat only other animals. 3. Omnivores (e.g., humans and crows) eat both plants and animals. C. Animals can also be classified based on the size and location of the food that is ingested. 1. Suspension feeders ingest small animals, such as microscopic protists, and plants (whales, clams, oysters and tubeworms, Figure 21.1A). 2. Substrate feeders ingest by burrowing into their food (earthworms and caterpillars; Figure 21.1B). 3. Fluid feeders obtain nutrients from plant sap (aphids) or animal fluids (mosquitoes; Figure 21.1C). 4. Bulk feeders are those that consume larger prey whole or in pieces (most animals; Figure 21.1D). Module 21.2 Overview: Food processing occurs in four stages. A. Food processing can be divided into four stages (Figure 21.2A). B. Stage 1: Ingestion is the act of eating. C. Stage 2: Digestion is the breakdown of food into molecules small enough to be absorbed. Digestion occurs in two steps: mechanical and chemical breakdown. Mechanical digestion occurs in the mouth. During digestion, larger polymers are chemically digested into smaller
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components by hydrolysis (Module 3.3; Figure 3.3B). Specific enzymes catalyze each step of digestion (Figure 21.2B). The products of digestion are then used for either cellular respiration or biosynthesis (Modules 6.14 and 6.15). D. Food consists of large polymeric fats, carbohydrates, proteins, and nucleic acids that animals cannot absorb directly. All animals need the same monomers: fatty acids, simple sugars, amino acids, and nucleotides. E.
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This note was uploaded on 03/10/2011 for the course BIOL 10 taught by Professor Kite during the Spring '11 term at Laney College.

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Chapter 21 - Introduction A Feeding(ingesting food is a...

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