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Lab 10 Food Web. BY-102 Zach Nolen. What is a food chain?. The order of who eats who Examples: Seeds → Grasshopper → Mouse → Owl. What about a Food Web?. Interconnection of several food chains to form more complex relationships. Trophic Levels. - PowerPoint PPT Presentation
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LAB 10FOOD WEB
BY-102Zach Nolen
WHAT IS A FOOD CHAIN? The order of who eats who Examples:
Seeds → Grasshopper → Mouse → Owl
WHAT ABOUT A FOOD WEB? Interconnection of several food chains to
form more complex relationships.
TROPHIC LEVELSAre based on the position that an organism holds in a food chain.
FOOD SOURCESClassificati
onFood Source Examples
Producer Produce their own from sunlight
PlantsGrass
Herbivore Eat producers BeetlesGrasshoppers
Carnivore Eat other animals OwlsShrews
Omnivore Eat other animals and producers
Field mice Birds
Decomposer Only dead organic matter MushroomsBacteria
OWL VIDEO
TRY TO ANSWER THE FOLLOWING QUESTIONS.1. Where do they live?2. How long do they live?3. Where do they hunt?4. How many owlets do they have?5. When do the owlets hatch?6. Why are owls such good hunters?7. How are owl pellets formed?8. Describe the digestive process of the
barn owl. Number and name(s) of stomach(s), etc…
9. What dangers do barn owls face?
REVIEW QUESTIONS
WHERE DO THEY LIVE? Tyto alba (Barn Owl) Habitat
BarnsSilosHollowed trees
HOW LONG DO THEY LIVE? In the wild: 1-5 years Protected environments: 20-25 years
HOW MANY OWLETS DO THEY HAVE? Average clutch size is 4-7 owlets
WHEN DO THE OWLETS HATCH? Eggs are laid 2 days apart and hatch in
2 day intervals
DESCRIBE THE DIGESTIVE PROCESS OF THE BARN OWL. 2 stomachs
Glandular stomach – secretes digestive enzymes to separate the fleshy portions of prey from the bones, hair, and fur.
Muscular stomach – further breaks down fleshy portions of food.
HOW ARE OWL PELLETS FORMED? Prey is
swallowed whole Reached
gladular stomach. Fleshy portion passes to next stomach.
Hair, feathers, and bones remain in glandular stomach.
HOW ARE OWL PELLETS FORMED? Fleshy portion is
further broken down by muscular stomach and nutrients are absorbed.
Waste matter (uric acid) is excreted.
Hair, feathers, and bones are compacted into a bolus in the glandular stomach and regurgitate.
WHAT DANGERS DO BARN OWLS FACE? Harsh weather conditions Busy railways and motorways Loss of habitat Drowning in water troughs Loss of suitable nesting sites
POTENTIAL PREY OF TYTO ALBAShrew
Mouse
Rat
Vole
Bird Insect
WHAT IS A DICHOTOMOUS KEY? A tool that allows easy identification of
items. Key provides 2 choices at a time Think of these as a “choose your own
story” where your choices affect the final outcome.
DISSECTING OWL PELLETS Open foil
wrapping Gently find a
place to start your dissection
Use tweezers, probes, and your hands to separate the bones from the hair and feathers.
DISSECTING OWL PELLETS After you have found as much as
possible, use the dichotomous key on page 111 to identify any skulls that you found.
If you did not find any skulls, use the key on page 112 to match the bones that you found.
CLASS FINDINGS
REVIEW QUESTIONS1. What is a food chain?2. What is the difference between a food
chain and a food web?3. What is the scientific name for the
barn owl?4. How are owl pellets formed?
BEFORE YOU LEAVE LAB Clean up your work station.
BEFORE NEXT LAB Complete all sections of lab manual for
final lab manual check Complete Study guide 3 (Optional) Study for test