Ecological Pyramids ( Part 2 0f 2)

This is the second part of the lab which relates to the owl pellet dissection lab.

A.      Number Pyramid for a 24-hour Period

·         Only students with last names starting with A through H perform this part.

·         What to submit for this part:

o   A drawing or depiction of the completed number pyramid, scan or photograph. You may not copy and paste someone else’s pyramid 

o   Calculations for number 3, 4, and 6 

o   Answers to questions 1-4 

A number pyramid is an ecological pyramid that indicates the total number of organisms in each trophic level.

 

1.       Draw your pyramid on a separate piece of paper, labeling the number of 3^o, 2^o, and 1^o consumers. Remember, your one owl, represented by the one pellet, is the 3^o consumer.

2.       From the number of skulls in your pellet (same type or different types) determine the number of prey consumed. One skull = one prey animal. If your pellet does not have any skulls, then make an estimation of the number of animals based on large parts of the skeleton, such as shoulder blades (scapulae) or hips (pelvises).

Determine the ratio, R, of the number of 2^o consumers to the number of 3^o consumers.

R = # 2˚ Consumers          R= 7 Prey        R= 7

       # 3˚ Consumers                 1 Owl

       

3.       Use R to calculate the number of 1^o consumers by multiplying the number of 2^o consumers by R.

 R= 7      7(7) = 49

# 1^o Consumers = R (# 2˚ consumers)

                                                      #1 Consumers 49 = 7 (7 Secondary Consumers)

4.       Label your pyramid with the number of 1^o consumers.

5.       Calculate the number producers by multiplying the number of 1^o consumers by R.

# Producers = R (# 1˚ consumers)

 6.       Finish your pyramid by labeling it with the number of producers.            

Answer these questions.

1.       What are owl pellets? 

                Owl pellets are essentially owl feces however instead of being produced through the anus as other animals the excess waste is regurgitated from the mouth in a non-odorous pellet form. 

2.       During the nesting season the young need an enormous amount of food for growth. If the nest contains three young and each of the young eat five mice per night for a month and the two adults eat four per night, how many mice would the parents have to capture in 30 days?

                We can find that out doing some simple math.  Three young owls’ times five mice is fifteen.  Two adult owls’ times four mice is eight.  We add fifteen and eight which is twenty three.  So that would be twenty three times thirty which is six hundred and ninety mice.

3.       The pellets are from what owl family?

                The pellets are form the common barn owl also known as Tyto Alba.

4.       Environmentalists are concerned about the accumulation of certain poisons in predators. Why do you suppose owls, eagles, swordfish, humans and lions are often the most threatened organisms of a community that are exposed to DDT or mercury?

                I believe it is because the producers and secondary consumer have ingested excess amounts of these poisons and then pass it on to the tertiary consumers.  Tertiary consumers get less energy from what they eat compared to other animals, so when impure meat or plants are consumed it effects them more.  A food chain can really show this process well or a pyramid of energy.