The snapping turtle shown above, lives in a small farm pond, where its major prey is largemouth bass. In turn, the bass primarily eat emerald minnows. This snapping turtle weighs 40 pounds. If the pond has 10 mature snapping turtles of this size, how many pounds of minnows are required to support them? [Use the 10% law across each trophic level.]

A) 400

B) 4,000

C) 40,000

D) 400,000

C. 40,000 is the answer

One snapping turtle weighs 40 pounds, so 10 snapping turtles in a pond have a total weight of 400 pounds. The turtles eat largemouth bass (1 trophic level below them), and the bass in turn eat minnows (2 trophic levels below the turtles). So since only 10% of energy is passed in each trophic level, we would need:

(x lbs of minnows) (10%) (10%) = 400 lbs of snapping turtles

x = 40000 lbs of minnows (Choice C)