Name:Date:Period:
Physiology Laboratory 2015

A Study of the Skeleton through the Dissection of an Owl Pellet

Introduction:

The study of the skeletal system can be done at three different levels; at the gross or macroscopic level, at the microscopic level and at the chemical level. At each level of study, information pertaining to the importance of the skeletal system to the functioning of the body as a whole will be uncovered.

During the next couple of weeks, we will have the opportunity to study of the skeletal system at each of these levels. To begin our study, we will look at the skeleton at the macroscopic level. To do this we will dissect an owl pellet and reconstruct one animal from the bones recovered.

An owl is a raptor, or bird of prey, which hunts for its food. When it finds lunch or dinner, it swoops down and swallows it whole. Strong enzymes digest the prey in the owl’s stomach and the remnants, non-digestible materials, bones and fur, are regurgitated in the form of a soft pellet. Scientists then go out and collect these pellets for study. The ones we are going to use have been dried for easier handling.

Materials:

Owl pelletforcepsdissecting probe

Water bottlePetri disheschina marking pencil

Metric rulerbalancestring

Procedure:

  1. You will be working in teams of two for this lab. Get an owl pellet and the rest of your supplies from the side of the room.
  1. Unwrap your owl pellet, and write observations pertaining to the look and feel of the pellet and anything else you find interesting about it.
  1. Cut a piece of string, approximately 6 inches long. Use the string to get an accurate measurement of the length of your pellet in millimeters. Then use the string to measure the diameter/circumference of your pellet in millimeters. Weigh your pellet to the nearest gram on the balance. Record your pellet data in the chart for your report. Bring this data to class on ______so that we may gather all the groups information.
  1. Now begin to dissect your owl pellet. Be very careful as the bones are delicate and sometimes quite brittle. They are also intertwined with the remaining fur and stick together.
  1. Here are a few helpful hints to guide you through the dissection:
  1. Use water to dampen, NOT WET OR SATURATE the pellet. You do not want the bones to sit in a pool of water.
  2. Using your forceps, begin to pull apart the fur and pick out all the bones you see.
  3. Once you have picked through the pellet with your forceps, now it is time to get down and dirty. The best way to get all the bones is to go through the fur with your fingers. GENTLY rub small bits of fur in between two fingers and pick out all the bones you feel.
  4. You should keep all the bones separate from the fur you have not gone through by placing the bones in a Petri dish. If you do not finish going through the fur completely today, wrap the remaining pieces of pellet in aluminum foil, and write your name on it. Make sure your name is also your Petri dishes as well.
  1. After you have removed all the bones throw out the fur-MAKE SURE I have checked the fur before you throw it out!
  1. Using the attached charts, and the books at the front of the room, identify the types of bones you have collected. Count each type and record the data in the chart at the end of this protocol.
  1. Using the skull charts, make an identification as to what animals you have in your pellet.

Assignment: is in two parts

PART I: Reconstruction -Your assignment is to reconstruct ONE animal as completely as possible from the bones you have collected. You have a choice as to how to make your reconstruction—

  1. 3 –Dimensional reconstruction in which your animal will be standing

You will need to use fishing line and glue, as well as some toothpicks for this project. (Yes, this reconstruction will gain you more points than choice b.)

OR

  1. flat poster-like 2-dimensional reconstruction, this needs to be done on a hard piece of cardboard.

Whichever you choose, you MUST

have labels or a key identifying all the bones

identify the specific type of animal you are reconstructing

put your name and lab partners name on the reconstruction

PART II: Your written reportmust contain

Cover page- name, title, date, period, teacher’s name

  1. Introduction about owls which includes what scientists can tell from the study of the pellet about where the animal lives (environment), what they eat, and why they are important in the ecological food chain, as well as any other special interesting facts about owls. This should be at least 1 page long and requires citations.
  1. Observations about the owl pellet you dissected – this should be detailed and contain A LOT of OH WOW bits of information.

i.The data you collected on your owl pellet and the class data chart. Including the masses of all the owl pellets and your own owl pellet bone count tally. In other words, how many femurs did you find? Ulna? Skulls? This can be done in a chart format.

  1. A comparison of your owl pellet data to the class average. (Should be about a paragraph long.)
  1. Conclusion – After watching the video and completing your dissection, discuss why there is so much variation in the number of bones and species that can be contained in one pellet. (HINT- think about environmental influences) Citations required!!

Helpful links for your conclusion! Aren’t we so nice

(pretty)

(shows Bones)

Lab and Reconstruction Due: Friday, December 18th

NAME:______LAB PARTNER:______

BONE DATA FOR OWL PELLET LAB

Length: ______mm

Circumference: ______mm

Mass:______mm

BONE CHART FOR OWL PELLET LAB

Type of Bone / Number found in pellet
Innominate (pelvis)
Scapula
Femur
Fibula
Tibia
Humerus
Ulna
Radius
Ribs
Vertebrae
Skull*
Mandible**

You do not need to count the hand and feet bones, but they should be kept for your reconstruction.

*Using the identification chart included with this lab protocol, identify the types of skulls you have recovered. Note the shape and associated teeth in your identification.

Animals found in owl pellet, based on skull identification -

SKULL:a.

b.

c.

**The mandibles (bottom jaws) you will recover usually are found in twos or halves, so two halves equal one mandible.