Eating and Not Being Eaten

Chapter 6--Ridley

Modified: 2005-11-20

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Eating

• Herbivory
  • Eating Plants
    • Folivory (leaves)
    • Frugivory (fruits)
    • Graminovory (grasses)
    • Granivory (nuts)
    • Gumivory (saps, gums)
    • Nectarivory (nectar)
• Carnivory
  • Eating other living animals
    • Crustacivory (crustaceans)
    • Insectivory (insects)
    • Molluscivory (mollusks)
    • Myrmecophagy (ants and termites)
    • Piscivory (fishes)
    • Planktonivory (plankton)
    • Sanguinovory (blood)
• Scavenging
  • Eating dead animals
• Parasitism
  • Living inside or on a host animal

Feeding in group-living herbivores

• Serengeti Plains Ecology
  • Herbivores
    • Zebras (non-ruminant, eat mostly stems, first to migrate)
    • Wildebeest (ruminant, eat mostly leaves, next to migrate)
    • Topi (ruminant, eat both stems and leaves)
    • Gazelle (ruminant, eat mostly fruits, last to migrate)
      • Ruminants
        • have multiple stomachs
        • take longer to digest food
        • more efficient in extracting energy
      • Non-ruminant
        • have one stomach
        • digest food quickly
        • less efficient in extracting energy
  • Carnivores
    • Lions (group hunting, 30% success rate)
      • Females do most of hunting (15% success rate)
      • Males, however, hunt larger prey
      • Stealth and surprise used in hunt
      • Prey animals track lions's hunting and act accordingly
      • Males eat most of kill
      • Females and offspring get leftovers
      • Hunt both during day and night
      • Steal kills of other Serengeti predators
    • Hyenas (group hunting)
      • Nocturnal hunters
      • Males and females nearly indistinguishable
      • Consume nearly all parts of prey animals (leaving little evidence)
      • Also scavenge and steal kills of other predators
      • Group hunting is not really organized
    • African Hunting Dogs (group hunting)
      • Most social of group hunters
      • Hunts gazelles, impala, and wildebeest calves, but also larger prey
      • Chase prey for miles in long line of hunting dogs
      • Regurgitate food for pups back at den
      • Have large litters
    • Leopards (solitary hunter)
      • The nocturnal eye--site describes how nocturnal eyes work
      • Leopard eye--site briefly discusses leopard eye and how it's used in hunting
      • Stealthy , nocturnal (mostly) hunters
      • Sneak up on prey and lunge from short distance
      • Tend to cache kills in trees (they are good climbers)
    • Cheetahs (solitary and small group hunters)
      • Extremely fast-running predator
      • Long legs and flexible bodies aid speed
      • Hunt during morning and evening (not at night)
      • Hunt small prey
• Other Locations
  • Wolves (group hunting, low success rate)
    • Nearctic distribution now, nearly all of northern hemisphere in past
    • Cooperative group hunters
    • Hunt wide variety of small and large prey
    • Moose hunts very unsuccessful (4.6 % success rate, Mech, Isle Royale data)
      • Moose can stand their ground against a wolfpack (picture)
      • In moose kills, nose is usually eaten. In deer kills, nose is nearly never eaten.
      • Wolves do not attack or prey on humans.
  • Coyotes
    • Smaller than wolves
    • Eat wide variety of small prey (including dogs!)
    • Highly adaptable, range has expanded dramatically

Recognizing Food

• Food vs. Non-Food
  • Distinction depends on species
  • Toad food behaviors
    • Small, dark, moving objects are food (flick first, decide later)
    • Large, dark, moving objects are avoided
    • Thus, food itself, is not recognized
  • Search Images
    • Hypothetical construct
    • A mental image of food
    • Useful when searching for cryptic prey

Hunting Food

• Foraging on immobile prey
  • Searching for food that does not move
  • Static food can be evenly distributed or clumped
  • Optimal foraging theory predicts that animals will maximize benefits (calories or nutrients) and minimize costs (time, effort)
• Fish Schooling
  • Aquatic ecologies are mostly carnivorous (big fish eat little fish)
  • Schools are dynamic and clumped
  • Schools are hydronamic (make swimming easier)
  • Predators must find schools
  • Schools protect members (difficult to find and center of school is safer)
  • Functions include: travelling, resting, evasion, and feeding
• Avoiding Being Eaten: Active Evasion
  • Active flight is detecting predators and avoiding them
    • Bats and Moths
      • Noctuid moths can detect bat signals from bats 100' away and fly in opposite direction
      • Bats detect moths at about 8'. Moths detecting moths that close fly erratically
  • Camouflage
    • Blending into the environment
    • Both predators and prey use camouflage
  • Countershading
    • Darker top and lighter bottom pattern of coloration
  • Warning coloration (or aposematic coloration)
    • Monarch butterflies and cardiac glycosides
    • Predators quickly learn not to eat monarchs
    • Also seen in snakes and insects
    • Kin selection may explain evolution of warning coloration
  • Mimicry
    • Viceroys and Monarchs
      • Batesian mimicry is when palatable prey benefit from poisonous model
        • Coral snakes and king snakes (Red and yellow, kill a fellow. Red and black, friend of Jack.)
      • Müllerian mimicry is when both prey and models are poisonous
      • Aggressive mimicry is when predators appear insconspicous
        • Angler fish
        • Alligator snapping turtle
        • Photuris and Photinus (fireflies)

Domestication

• Animals
  • Short list of domestic animals includes: dogs, horses, sheep, goats, cattle, pigs, camels, and few others
  • Taming is different that domestication
  • Reasons for lack of more domestic animals include: diet, growth rate, captive breeding, disposition, panic tendency, and social structure
  • Herding dogs
  • Herd guarding dogs
• Plants
  • Eurasia
    • Wheat, barley, peas, lentils, chickpeas, vetch, flax
  • China
    • Rice, mung beans, soy beans
  • Africa
    • Rice, sorghum, yam
  • Americas
    • Maize (corn), squash, potatoes, sunflowers, tomato, peanut
  • Asia
    • banana, coconut, sugarcane
  • Only 15 species account for most of human diet
  • Other domestic plants supply natural fibers: cotton, flax, hemp