Warm-up October 1stDay 2 • Create a food chain using the following organisms. What do your arrows represent?? • Shrew Hawk Grasshopper • Homework Due: Food Chains & Webs packet
Warm-up October 1stDay 2 • Food Chain: • Grasshopper Shrew Hawk • The arrows show the flow of ENERGY!!
Activity Instructions • You will play the role of a hawk, shrew, or grasshopper… • 1. Grasshoppers get to collect food in their stomach (brown paper bag) while shrews and hawks watch their prey. • 2. Shrews hunt their prey (grasshoppers). **When you catch your prey you get their stomach! • 3. Hawks hunt shrews. Living shrews can still hunt grasshoppers until you get “eaten.”
Return to your seats… • All living animals should count the contents of their stomachs. • Count & record # light colored cereal • Count & record # of dark colored cereal Count them up!
Oh no!! A pesticide! • Farmers sprayed the crop that the grasshoppers were eating with a pesticide. • All dark colored cereal represents this pesticide!
What does this mean?? • All living shrews with half or more dark colored cereal are dead due to the pesticide! • The hawk with the most dark colored cereal will live, BUT so much of the pesticide accumulated in your body that the eggs of you and your mate will have a very thin shell and will not hatch!
How do toxic substances enter a food chain?? • Grasshopper Shrew Hawk
Biomagnification • Biomagnification is the increase in concentration of a pollutant from one link in a food chain to another • Can result in the accumulation of chemicals in species higher in the food chain.
Another Example • DDT (dichlorodiphenyltrichloroethane) was applied to crops to control insect damage. • In the early 1970s, it was discovered that DDT had entered the food chain. • Fish ate insects sprayed with DDT. • Hawks, eagles, and pelicans at the fish.
However… • DDT became concentrated in the birds body’s and their egg shells became very thin. • The weight of the adult bird would crush the eggs in the nesting process. • This impacted the population of our national bird, the bald eagle!