Name:______
Block:_____
Shrew Energy Exercise: Show work for credit!
The short-tailed shrew is a ravenous predator that is found throughout the plains states. Although it is seldom seen, it is common. There can be as many as 50 shrews living on one acre of land, with 10 to 20 shrews per acre common. Few animals are as hungry as a shrew. It must eat 11/2 times its own body weight in insects and other small animals in a single day. Solve the following problems so you can picture how much a shrew really eats. Energy info: 1 gram fat = 9 Calories
1 gram protein/carb = 4 Calories
4.2 Kilojoules = 1 food Calorie
1. The short-tailed shrew must eat 11/2 times its own body weight in insects each day. If a shrew weighs 19 grams and a grasshopper weighs 3 grams, how many grasshoppers must a shrew kill and eat in one day? (Count each grasshopper killed in a day. If only part of a grasshopper needs to be eaten, count the whole grasshopper.)
10 Grasshoppers
2. If the grass captures 20,000 kilojoules of energy from the sun, and grasshoppers eat the grass, how much energy in Calories is passed to the shrew from one grasshopper?
HINT: 4.2 Kilojoules = 1 food Calorie (C=kilocalorie)
How much energy in Calories is passed to the shrew per day?
47.6 Cal to Shrew
476 Cal/day for shrew
3. If a fox eats a shrew, how much of the original energy from the grass is passed on to the fox? Draw a pyramid to show this.
4.76 Cal or 20 kJ
4. How many Calories will the shrew consume in one year? How many of those Calories will be lost if he is eaten on his first birthday by the fox?
173,740 Cal/yr
Lost – 156,330 Cal
5. If 20 shrews lived on one acre and you had 5 acres of land, how many ants would it take to sustain the shrews for one week? Assume that each ant is .01 gram with 5% fat. Assume each shrew needs 476 Cal/day (#2).
About 7,840,000 ants
Sagebrush food web questions: See food web on back of page!
1. What order consumer is the coyote?
Secondary and Tertiary (2nd and 3rd Order)
2. If a coyote needs 2000 Calories per day, and a lizard has 10% body fat and weighs 20 grams, how many lizards would fulfill the coyote’s diet? Show work.
22.2 so 23 lizards
3. If the sagebrush captures 40,000 kilojoules of energy from the sun, how much that energy is passed on to the raptor, assuming he ate a snake?
40 KJ
4A. If there was a disease in the population of small rodents, and 60% died off, what other populations would be affected? Describe why or how for each.
Vary
4B. If a badger’s diet consisted of 1 rodent, 1 snake and 2 lizards per day, how would he make up for the loss of the rodent in his food supply? (rodent=50g and 30% fat, lizard=20g and 10%fat, snake 25g and 8% fat)
3 snakes
2 snakes and 1 lizard
About 3 lizards
Show work for Calorie content of each!
5. If a baby squirrel is 40% fat and weighs 15 grams, how many baby squirrels must the badger eat in a week? Assume his daily requirement is 400 Calories and this is his only food source at the time.
31 baby squirrels
6. A great-horned owl lives for 4 years before falling out of a tree and being eaten by a mountain lion. Everyday, the owl ate 3 small rodents at 200 Calories each. How much of this energy is lost over the course of the owl’s lifetime?
788,400 Cal lost