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