Comparing Two Turtles

Written by Sandie Nichols

National Science Education Standards:

Content Standard: Level 5-8

Unifying Concepts and Processes

§       Evolution and equilibrium

§       Form and function

Life Science

• Regulation and behavior
• Populations and ecosystems
• Diversity and adaptations of organisms

 

 

Background

Turtles and tortoises are often lumped together under the name “turtle”. Students generally know the difference but misuse the terminology anyway. In elementary school, students learn the difference between reptiles and amphibians, and turtles and tortoises.

Loggerhead Sea Turtle:

The Loggerhead Sea Turtle lives in the oceans around the world. In this area, they hatch from the beaches and spend their juvenile years in the Sargasso Sea. They eat sea vegetation and when older, eat jellyfish and invertebrates such as crabs, mussels, clams, and lobsters. Turtles must surface for air but can hold their breath for long periods of time. They rest on the bottom, sleeping, while other creatures clean their bodies. Adult loggerheads can reach 350 pounds in size.

The loggerhead will reach sexual maturity around 14 years of age. Females return to their natal beach for nesting every few years. They will lay 2-3 clutches over a two week period. The nests contain about 100 eggs. Loggerheads can live from 50-100 years. The natural predator for adults is the shark and humans.

Eastern Box Turtle:

Tortoises are land dwellers. They live in the forests, fields, and wetland areas. The Eastern Box Turtle can have a range of 5-12 acres. They eat a multitude of invertebrates such as crickets, worms, beetles, and some vegetation. They will eat berries, snails, leaves and sometimes lizards and fish. They have some camouflaging in their shells and often hide in the grass. They do not tolerate heat and will bury themselves in the soil to keep cool. Tortoises do not completely hibernate in the winter in the southeast. They slow down and bury themselves in the soil, sometimes very deep. The box turtle can grow to be the size of a small dinner plate.

The box turtle will reach sexual maturity around 5 years of age. A female tortoise will lay several clutches every year. Each nest will contain three to eight eggs. The nests are buried under the soil and compressed by the tortoise’s body. The incubation period is 75-90 days depending on the temperature and rainfall. Tortoises can live up to 40 years. Adults have few natural predators except humans. Tortoises pull their head and legs inside their shell for protection.

 

 

 

Materials:

1 plastic sea turtle and 1 plastic tortoise per group

field guides

encyclopedias

books about turtles

5 gallon bucket with sand

100 ping-pong balls (30 already labeled with concept words)

• Possible words:          hatchling         natal imprinting                      temperature-dependent sex determination               maturity           incubation       Sargasso Sea

boiling             hatchling frenzy           caruncle          pipped egg       lost years                                

 

Engagement

Begin the lesson with a KWL chart showing what the students know about a turtle and a tortoise. List the information under the K portion on a T chart. Add what the students want to know about turtles and tortoises on the W portion.

 

Exploration

Give the student groups a plastic model of a sea turtle and a tortoise. Allow them to compare the observable differences.

 

Elaboration

Discuss the reasons for the observable differences. Discuss form versus function.

(The claws on the tortoise are for foraging on land and the flippers on the sea turtle are for swimming.)

 

Explication

Revisit the KWL chart and fill in new knowledge or discoveries. Revisit the W portion and see if any questions have been answered. Allow students to access field guides, encyclopedias, and internet resources for more in depth information.

 

 

Evaluation

Students will create a Venn diagram to compare and contrast the sea turtle and tortoise. Information should include habitat, prey, predators, body form and function, lifespan, reproduction, and size.

 

 

Conclusion and Summation

Provide a visual in the form of a 5 gallon bucket of sand and 100 ping-pong balls. Show the students how and what a nest would look like. Reinforce the concept that only 1-2 hatchlings will survive to adulthood out of each thousand eggs laid.

Fill a bag with 30 ping-pong balls previously labeled with concept words. Allow each student to reach in without looking and choose one ball. In their group of four students, have them come up with a paragraph about what they learned using all of the words. Student groups will share their writing with the class.