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Sea Turtles by Devin and Zach

Aloha! We live in Maui, where the surfing is awesome! Anytime we're in the water, there's a chance we'll see one of our favorite animals, the honu, or sea turtle. We know that it is important to leave the honu alone in the wild, but we also know that their population is shrinking. We went to the Maui Ocean Center to learn more about the honu, and to find out: how quickly do honu grow?

What did we do?
Working with a staff aquariast and a marine scientist, we were able to weigh each of the six young honus in the Turtle Lagoon exhibit. While we had them out of the water, we also measured the length of their shells. We combined this data with some the Maui Ocean Center had on hand from previous check ins with the turtles. We used all this data to graph the turtles growth rates early in life. Then we estimated what we thought the turtles would weigh—and how long their shells would be—when they are 3 years old and ready to be released into the wild. We compared our predictions with actual data from other 3-year-old turtles at their release.

What did we find out?
We learned something really interesting. Honus grow really fast when they are quite young. But as they approach their third birthdays, their growth rates slow—kind of like how the growth rates of human beings slow after childhood. Interesting!

What can you do?
  • There are at least two body characteristics you could use to determine an animal's growth rate: its length, and its weight. Imagine being able to study animals like sea turtles up close, without harming them. What kind of measurements would you make to figure out how quickly they grow? Over how many months or weeks would have you to collect data. Design a plan for monitoring the growth of a sea turtle, or any other creature. Write your ideas in your notebook.
  • You probably already have the data you need to make a growth rate chart for your own body! Ask your parents, or even your doctor's office, for information about your height and weight. Your family may have a "baby book" with these measurements, or perhaps you have a wall chart in your bedroom where you mark your height every few months. Turn this data into a graph, and compare your growth rate to that of your classmates or friends!
  • Consider doing a growth rate investigation on plants. Choose a perennial plant (one that re-emerges from the ground each year), and keep a daily record of its height for a month or two, starting when it first emerges from the ground. Plot the growth data on a graph, and look for portions of the graph that indicate when the plant grows most quickly, and when it grows most slowly. You might consider keeping weather data, such as air temperature, sky conditions, or precipitation, to look for a relationship between growth rate and weather conditions.
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