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An alligator's sexual characteristics can't be seen externally. Older males can sometimes be identified by their massive, rugged-looking heads, but it's impossible to determine the gender of a baby alligator by his outward appearance. An internal examination of an alligator's vent, or cloaca, located on the creature's underside, is the only means of determining gender -- which was determined by incubation temperature when the alligator was an egg.
The Physical Appearance of a Baby Alligator
Baby alligators hatch from their eggs snapping and biting. Newly hatched alligators are approximately 6 to 8 inches long; as adults they may eventually grow up to 15 feet long. They're black or greenish-black, and they have pale yellow streaks along their sides. Their eyes face outward on their broad heads, and their long snouts turn up slightly at the nostrils. All the babies from one nest share the same color markings.
Nest Temperatures Determine Nestling's Gender
In July or August, the female alligator builds a 10-foot-diameter nest of marsh vegetation. She lays 20 to 30 eggs in the center, piling the vegetation three feet high. The composting matter generates the necessary heat for incubation. Baby alligators hatch in about 60 days. Males will hatch from nests that maintain temperatures of 93 degrees Fahrenheit or higher, and females will emerge from eggs kept at 86 degrees Fahrenheit or lower. Nests incubating between these temperatures may contain both sexes.
Internal Examination of a Newly Hatched Alligator
A professional can determine the gender of a very small baby alligator, 6 to 10 inches long. One method is to place the creature on its back and hold open his vent with round-tipped tweezers or forceps, with a helper's assistance. Using an illuminated magnifying glass, he can examine the sex organs located inside the cloaca. The male's sex organs completely fill the cavity, and the female's sex organs are about half as large.
Determining the Sex of Older Baby Alligators
You can determine the gender of juvenile alligators measuring less than 30 inches long with a similar method. A helper must hold the juvenile. On a flat surface, lay the alligator on its back. Bend the tail upward while using your thumb and forefinger to apply gentle pressure below the pubic bones, located at the cloaca. If the juvenile is a male, a penis will protrude from the vent.
- National Geographic: American Alligator
- Louisiana Alligator Advisory Council: Alligator Mississippiensis
- Discover Magazine: Alligators Live Forever
- University of Arkansas at Little Rock: Alligators and Crocodiles
- Louisiana Wild Life and Fisheries Commission: Methods of Capturing, Marking and Sexing Alligators
- Jupiterimages/Photos.com/Getty Images