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