Overview of Animal Nutrition and Ingestion

  • Nutrition: process of consuming and using food and nutrients
  • Nutrient: any substance consumed by an animal that is needed for survival, growth, development, tissue repair, or reproduction
  • All organisms require nutrients to survive

What Do Animals Require?

  • Five categories of organic nutrients
    • Carbohydrates
    • Proteins
    • Lipids
    • Nucleic acids
    • Vitamins
  • Inorganic nutrients
    • Water and minerals

Essential Nutrients

  • Essential amino acids: in order for protein synthesis to occur in human adults, eight amino acids must be available simultaneously and in the correct relative amounts.
    • Can be obtained from meat.
  • Essential fatty acids: important for phospholipid membrane; and principal storage compound.
    • Found mostly in plants.
  • Vitamins: organic molecules in small amounts; serve as coenzymes
    • Water soluble and fat soluble
  • Minerals: inorganic molecules in small amounts

Dietary Categories

  • Herbivores: mainly eat plants and algae

    • Gorillas, cows, hares, snails
  • Carnivores: eat other animals

    • Sharks, hawks, spiders, snakes
  • Omnivores: consume animals, plants, and algae

    • Roaches, crows, bears, raccoons, humans
  • Most animals are opportunistic: eating food

    that are outside their main dietary category

Strategies for Obtaining Food

  • Ways in which an animal obtains its food are related to its environment
  • Suspension feeding: filter organic matter out of water
    • Bivalve molluscs, sea squirts, baleen whale
  • Bulk feeding: they use many modified body parts like tentacles, beaks, claws, pincers, etc.
    • Eat food in large pieces
  • Fluid feeding: lick or suck fluid from plants or animals
    • Do not need teeth except, perhaps, to puncture an animal’s skin

Passive or Active Absorption

  • Nutrients must be absorbed by the epithelial cells lining the digestive tract
  • Three ways:
    • Passive diffusion 
    • Facilitated diffusion
    • Active transport

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