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Inspired by Venetia Butler's Babies! Babies! Activity in the Ocean Society's Sea Turtle Activity Booklet
Background Information:
Female loggerhead sea turtles return to the same region where they were hatched (called the natal region) to make their nests. The female uses her hind flippers to dig the nest or "egg chamber". The nests are often described as "flask shaped" with a depth of approximately 60 cm (24 in) depending on the length of the rear flippers. A female can lay approximately 100 eggs in each nest. These eggs will incubate for 60-70 days depending on the temperature of the sand. Temperature is also important in determining the sex of the hatchlings; generally cooler temperatures produce males and warmer temperatures produce females.
Most of the sea turtles will begin to hatch at the same time as they cut through the soft leathery shell of their eggs. Digging their way out of the nest is a group effort by the hatchlings and is termed "social facilitation". Each digging turtle loosens sand, which falls to the bottom of the nest. As the sand accumulates at the bottom the hatchlings are moved upwards. The sand acts like an elevator. The process of emergence (reaching the beach surface) can take several days depending on the depth of the nest and the compaction of the sand. As the hatchlings approach the surface they will pause and wait for the temperature to drop below a certain threshold before they will "erupt" or "boil" out of the nest.
Demonstration:
- Make your "emergence" jar by placing a small rubber turtle or ball in the bottom of the jar. Fill the container half full with rice ensuring the ball or turtle is completely covered with at least an inch of rice.
- When it is time for the demonstration, take out the jar and swirl it quickly so that the rice starts to settle to the bottom. This will push the ball or sea turtle upwards.
Activity Steps:
- Have students make nests out of clay
- Ask the students to write down their ideas on how sea turtles emerge from the nest. Ask them to be as specific as possible.
- Show the demonstration and explain the process of emergence.
Now its time to get hatching!
Which Way's Up?
Procedure:
- Using the clay provided by your teacher, build a sea turtle nest and eggs. The nest should have the general shape of a chemistry flask (Fig 1). Lay the eggs at the bottom of the nest and then let the nest and eggs dry.
- In the space below, describe how you think sea turtles hatch and emerge from the nest. Be as specific as possible.
- Watch what happens in your teacher's model as a single sea turtle makes its way out of the nest!
Figure 1
Discussion Questions:
- Compare what happened in your teacher's demonstration to your idea. How is it similar or different from what you observed?
- In the demonstration there was only one hatchling emerging from the nest. Do you think a hatchling could reach the surface on its own in the wild?
- If the sand did not help to lift the hatchlings up do you think they could make their way to the surface?
- Would it be easier for hatchlings to get out of a nest with wet or dry sand?
Conclusion:
Emergence is just one step in a long line of obstacles that sea turtle hatchlings must face. Now do you understand how working together can make this process more successful?
This Activity is available as a printable PDF for your convenience.
Which Way's Up (Adobe PDF, 127 KB)
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