Turtle Trails
Project NarrativeResearch LogsMapsPhoto GalleryActivitiesAsk the Team
Location: Home / Activities / Head's Up!

Background Information:
Loggerheads get their names due to the fact that their heads are very large compared to their body size. These sea turtles can grow up to 4 feet in length and can weigh up to 350 pounds! All turtle shells consist of two parts, the carapace (upper shell) and the plastron (bottom shell). The adult loggerhead's carapace is usually reddish-brown, while the plastron can range from a yellow to a light orange color. Loggerhead hatchlings' carapaces vary from light to dark brown while their flippers are dark brown with white edging. Some sea turtles can acquire barnacles or seaweed on their carapaces as well.

Measurements:
The diameter of a loggerhead's head is 38 cm. The loggerhead's carapace (top shell) length is 63.6 cm. Measurements were obtained from adult members of the aquarium staff. We took the diameter of the head (around middle of forehead) and the length of the person from the nape of the neck to the floor to obtain our human averages. This gave us an average diameter of 56.2 cm and an average length of 149.5 cm.

Formulas

We found that a human head would need to have a diameter of 89.7 cm to equal the loggerhead ratio. We then converted centimeters to inches for easier visualization. (Multiply centimeters by 0.393 to find inches and then convert to feet.)

Now let's see if your students get the same answer!

Procedure:
  1. Collect materials (calculator, measuring tape, string or chalk, pencil and paper).
  2. Measure the diameter of your classmate's head as well as the length from the nape of their neck to the floor (See fig 1). Record the data.
  3. Calculate the average human length and head diameter for each group. Using these values, calculate the ratio of the human head to length (nape of the neck to the floor).
  4. Given the loggerhead's head diameter is 38.0 cm and its carapace length is 63.6 cm, calculate the head to carapace ratio.
  5. Using the information from steps 3 and 4 set up an equation to determine the diameter of a human head if it has the same head to length proportions as a loggerhead.
  6. For easier visualization convert the answer to feet and then use string or chalk to make a mock head in the classroom.
Fig. 1
Figure 1
Discussion Questions:
  1. Did you get the same answer as the aquarium staff?
  2. If not, what is the difference between your class and the aquarium staff?
  3. How can you obtain a more accurate answer?
  4. Can you think of other human/turtle comparisons that would be interesting? If so, e-mail us and we will provide the necessary turtle measurements.
Conclusion:
After completing this activity, would you agree that the loggerhead deserves its name?


This Activity is available as a printable PDF for your convenience.
Cold Stun Survey (Adobe PDF, 144 KB)

Grades: 6th - 8th

NC Standards:
Grade 6: Math- Goal 1-5, 1-7, 1-9, 1-13, 1-14
Grade 7: Math- Goal 1-5. 2-11
Grade 8: Math- Goal 1-12, 2-12, 3-1

Time Required (Estimated): 30 minutes

Purpose:
To figure out how large human heads would be if we had the same head to body proportions as loggerheads. This will be an introduction to characteristics of the loggerhead, measurements, ratios, conversions, and data collection.

Materials (per team):
  • Calculator
  • Paper (datasheet) and pencil
  • Measuring tape (flexible)
  • String or chalk