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Lecture 10

BIOL 1902 Lecture Notes - Lecture 10: Ruffed Grouse, Spruce Grouse, Radula

Course Code
BIOL 1902
Michael Runtz

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BIOL 1902 – Week 10
Animals face obstacle while eating plants:
- Digestion: hard to digest due to tough structural components
- Slugs & snails break off plant tissues w/ radula (mouth has miniature chainsaw-like
- Caterpillars have modified mandibles
oSome eat leaves from the inside – e.g. Leaf blotch miner
- Mammals use modified teeth
oBeavers & squirrels teeth are orange b/c full of iron
oIncisors never stop growing & self-sharpen
Moose have only lower incisors, so they rip off plant tissues
oLarge cheek teeth grind up food – powered by large masseters
- Mandibles, radula, & cheek teeth all perform same function, but arise from diff origins
(called analogous structures)
- E.g. Ruffed Grouse have no teeth
oBite off swelling buds on trees
- E.g. Spruce Grouse eat conifer needles
-Analogous to the radula, mandibles, & cheek teeth is the gizzard (grinds & turns food;
indigestion & digestion)
After ingestion, next problem: Digestion
- Slugs & snails produce digestive enzymes
- Caterpillars don’t produce enzymes – they waste a lot
oThey eat 10x their body weight every day
- E.g. Moose get help from bacteria
oChew cud (comes from stomach) – rumen
oFood processed twice (called rumination)
oSymbiotic relationship
- E.g. Hares & rabbits get help from bacteria
oCaecum (pl. = caeca)
oEat their droppings (beavers do this too) – this is called coprophagy
oE.g. dung beetles eat other animals’ droppings
- E.g. Snow Goose – have caeca
- Porcupines don’t eat their droppings – their digestive tract is about 26% of their total
- Most fruit-eating birds don’t only eat fruit
- Animals that eats fruits called frugivores
- Fruit-eating specialists – e.g. Bohemian Waxwing, Cedar Waxwing
- Large opening in bird = gape (large gape for external processing)
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