AMERICAN ALLIGATOR DIET
According to observation and stomach content analyses, American alligators are highly opportunistic and adaptive predators that have a wide variety of feeding habits and a largely encompassing diet (1).
Generally, prey of an alligator is directly related to its size. Juvenile American alligators eat smaller prey like insects, amphibians, small fish and other invertebrates. Adult American alligators eat larger prey like large fish, snakes, turtles, birds, small mammals and other vertebrates. However, majority of their diet, regardless of size, has been found to be composed of fish (1).
AMERICAN ALLIGATOR FEEDING
Alligators' large, conical teeth are optimal for forcefully seizing and holding prey, but not for tearing. Small prey, like fish, are swallowed whole. With larger prey that cannot be swallowed whole, alligators shake prey back and forth, tearing off flesh into more manageable pieces. If the prey is very large, the alligator engages in a spinning maneuver --nicknamed the "death roll"-- in which the alligator uses the long axis of their body to tear off swallowable pieces (2).
THE DEATH ROLL
The death roll was developed due to their teeth's lack of tearing ability. Tucking in their legs to centralize its mass and reducing drag, alligators contract their tail into a C-shape, which generates torque for forceful rotation (3).
In addition the muscles of the legs and tail, alligators contract four sets of torso muscles -- normally employed in breathing -- to shunt their lungs around like a buoyancy aid, which enables them to shift their weight and better perform death rolls (see Figures A and B below for further illustration). In fact, researchers suggest buoyancy control may have been the primary function these muscles, which later evolved to assist in respiratory functioning (4).
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Refer to the video (below) for a slow-motion look the mechanics of an American alligator's death roll. Note: The American crocodile doesn't regularly engage in the death roll as it's primary food source is fish - which it tends to swallow whole.
IMPORTANCE OF AMERICAN ALLIGATOR FEEDING
Survived from the brink of extinction, American alligators are currently thriving in the swamps and wetlands of the United States (5). It's important to understand the feeding habits of the American alligator in order establish management of alligator population for the present and future.
REFERENCES
1. Rice, Amanda N. "Diet and Condition of American Alligators (Alligator Mississippiensis) in Three Central Florida Lakes." (2004): n. pag. Florida Fish and Wildlife Conservation Commission. Web. 21 Mar. 2014. <http://myfwc.com/media/310266/Alligator_Rice_A.pdf>.
2."American Alligator." Fact Sheet. Smithsonian National Zoological Park, n.d. Web. 20 Mar. 2014.
3. Fish, F. E., Bostic, S. A., Nicastro, A. J. and Beneski, J. T. (2007). Death roll of the alligator: mechanics of twist feeding in water. J. Exp. Biol. 210,2811 -2818.
4. Uriona, T. J., and C. G. Farmer. "Recruitment of the Diaphragmaticus, Ischiopubis and Other Respiratory Muscles to Control Pitch and Roll in the American Alligator (Alligator Mississippiensis)." The Journal of Experimental Biology (2008): n. pag. Web. 21 Mar. 2014.
5."American Alligator." National Geographic. N.p., n.d. Web. 21 Mar. 2014.