Lecture 7 and 8


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LECTURE 7: NATURAL HISTORY DEFINITIONS AND EXAMPLES NUTRITION IN ANIMALS : EATING PLANTS TO FINDING PREY BY EYESIGHT Plants manufacture/make their own food, while Animals must obtain their nutrition from other sources (such as plants and other animals) Advantages of eating plants: they are easy to find/common, they don't move so no hunting involved Disadvantage of eating plants: hard to digest due to structural parts, plants have all sorts of defences, including chemical, physical. .. plants are only seasonal sources of food Advantages of eating animals: animal tissues is easier to digest/breakdown internally because they lack cell walls common to plant; higher return for effort ie more nutrition than eating plants Disadvantages of eating animals: have to hunt and catch them; animals can fight back (teeth, claws as weapons, etc.) presents danger Animals that eat plants: - herbivores eat plants as do omnivores (who eat both animal and plants) - parts of plants that are useful/eaten: leaves (insects), fruits, bark (beavers for example), roots (ie beetle grubs, june bug beetles), stems (ie beavers, moose), seeds, sap (liquids inside, ie in flowers there is nectar), pollen is also eaten - every part of a plant is usually eaten by animals – all parts are used - Two major groups of plants: (1) living parts of plant that's eaten; (2) dead plant material that is eaten - (1) DETRITUS = DEAD ORGANIC MATERIAL ON THE SOIL OR IN THE WATER - (2) DETRITIVORES = ANIMALS THAT EAT DETRITUS - DETRITIVORES = MICRO-ORGANISMS = TINY ANIMALS LIVING IN SOIL AND LEAF LITTER (swamp ground, in soil, surface, etc) - parasites in soil, mites are detritovores – mites all different colors, shapes and sizes, these are soil mites. Can be as many as 134,000 per metre squares (per m 2 ). These things start the whole process of breaking down and sending nutrients to soil and roots and so on - other animals in soil that are detritovores: earthworms (love dead leaves) – pull down into holes, they remove 90% of leaves on soil, break them down. Physical fragmentation of material. Can be as many as 3 million worms per acre! Charles Darwin was one of first to study worms. They eat their way through the soil. They can move 18 tons of soil/per acre/per year according to Darwin's calculations - In Ontario, there is 12-18 species of worms. Although NONE are native to Ontario, due to glaciation 10,000 years ago, so all our worms were wiped out. All of our worms were introduced - little black dots that jump around on snow (springtails) – out every winter – aka snow fleas, they hop on the snow. These are also in the soil and are considered detritovores - millipedes are detritovores – eats pollen, mostly feeding at night - Organic matter is also found in water, and can be brought to you, ie through filter feeders, who feed on organic matter via water passing through them. Most are vertebrates, examples include clams from bottoms of lakes who filter feed, filtered out by tiny hair like structures. Every year, 80% of the water in a lake goes through clams, by doing so this
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This note was uploaded on 08/13/2008 for the course BIOL 1902 taught by Professor Runtz during the Winter '08 term at Carleton CA.

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