• 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