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American Alligator, The (GMHDRNC)

TopicWildlife - Reptiles
Summary
This program touches on the history and future of the American alligator as well as the biological characteristics of Arkansas’s largest reptile.

Grade LevelK - 12
Recommended SettingIndoor or outdoor classroom
LocationGovernor Mike Huckabee Delta Rivers Nature Center, Pine Bluff
Contact

Education Program Coordinator, 870-534-0011

Duration45 minutes - 1 hour
Suggested Number of Participants10 - 30
Objectives
  • Learn the basic biology of alligators.
  • Show the physical adaptations of alligators for survival
Key Terms*

Carnivore

Crocodilian

Nictitating membrane

Osteoderm

Poikilothermic

Reptile

Scute

Materials

Alligator egg

Alligator skin and skull

Alligator teeth and scutes

Juvenile alligator

Background

The alligator is North America’s largest reptile, growing up to 18 feet. The alligator was listed as an endangered species as recently as 1967, but thanks to restoration, it is now in 45 of Arkansas’s 75 counties. To be classified as a reptile, an animal must be cold-blooded with scales. Most reptiles also lay eggs. Alligators have all three characteristics: rough scales, lay eggs and are poikilothermic or cold-blooded.

 

Procedure
  1. First discuss the alligators’ habitats: murky lakes, stale swamps and the muddy backwaters of rivers. Then discuss the physical adaptations that help them survive.
    • Their nostrils are at the tip of their long snouts to help them breathe while resting on top of the water. When they dive, a third, clear eyelid called a nictitating membrane slides across their eye and functions like goggles.
    • Alligators, like ducks and geese, have webbed feet. However, instead of using these to swim, their feet keep them from sinking in the muddy edges of swamps, akin to snowshoes.
    • Young alligators have a unique camouflage of horizontal stripes that help them blend with the top of the water. As they grow, the scales along their backs harden to bone. These bony ridges are a form of osteoderm called “scutes” that protect against predators.
  2. Discuss the feeding habits of alligators. Have the class run their tongues around their own teeth and talk about each tooth’s function. Relating this to alligators, they only have teeth for ripping and tearing, like our canines, and none for grinding, like our molars. They have to either swallow their food whole or tear off small hunks of larger prey.
    • Do alligators usually target humans as prey? No. Alligators are fairly shy and most would rather stay away. Besides being shy, alligators usually don’t pursue food that’s bigger than they are.
    • Alligators are opportunistic carnivores and will eat almost any meat they can swallow. However, they can only digest food when their body temperature is above 80 degrees Fahrenheit. Because of this, alligators don’t usually eat between November and March.
  3. Alligators reproduce by laying eggs. Explain the reproductive cycle of alligators. 
    • Unlike birds, alligators don’t sit on their nests. Ask why they think this is so, and remind them that, since the animals are cold blooded, they have no way to warm the eggs. They instead rely on a mass of rotting leaves and dirt to insulate the clutch of eggs.
    • The sex of the babies (about six inches at birth) depends on the temperature of the nest. Males are born from warmer parts of the nests and females from cooler parts.
    • A distinctive characteristic of alligators among the reptilians is that mothers usually remain with their young for up to two years, protecting them from predators.
    • It is also important to review the conservation history of the American alligator. 
    • When settlers to the southeastern United States forced other big predators from their home ranges, the alligator hung on in the millions in the heartland of the south. However, when their skins became fashionable after World War I, populations plummeted. During the 1920s, about 200,000 alligators were harvested yearly for their hides. By 1943, Louisiana alone lost more than 90 percent of their alligators. 
    • Finally in 1967, the government declared the alligator an endangered species and granted full protection. State and local agents created monitoring projects and restocked native locations with juveniles hatched in captivity. Within twenty years, the U.S. Fish and Wildlife Service pronounced it fully recovered. However, because the animal is similar to the extremely endangered American crocodile, they are still listed as threatened. The recovery was so successful in Arkansas that the state began to offer a few alligator hunting tags in 2007.
  4. Finally, present the live juvenile alligator. This can also be presented earlier in the discussion as a visual aid, or if presented at the end, use it to review some of the features you discussed earlier. If the group is small enough, or if there is enough time, participants may touch the animal. Stress the importance of hygiene and have participants clean their hands after contact.
  5. Allow time to answer questions.

 

Review
  • What human actions nearly led to the alligator’s demise? What brought the animal back?
  • Would an alligator enjoy a Thanksgiving feast? Why or why not?
  • How do alligators contribute to their ecosystems?

 

Related Documents
Glossary

Carnivore – any animal that consumes other animals, whether living (predation) or dead (scavenging)

Crocodilian – any reptile of the order Crocodylia, comprising the true crocodiles and the alligators, caimans and gavials

Nictating membrane – transparent inner eyelid in birds, reptiles and some mammals that closes to protect and moisten the eye; also called a third eyelid

Osteoderm – bony deposits forming scales, plates or other structures in the skin, often serving as defensive armor

Poikilothermic – refers to an organism whose temperature varies with the ambient temperature of the immediate environment; also known as cold-blooded

Reptile – any cold-blooded, egg-laying, air-breathing vertebrate of the class Reptilia, including turtles, snakes, lizards, crocodilians, amphibians, tuatara and various extinct members including the dinosaurs

Scute – a bony external plate similar to scales but derived from the epidermis; describes the scales of some armored mammals, such as the armadillo, and occasionally used as an alternative to scales in describing certain fishes, such as sturgeons