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Crocodilians Have the Ability to Swallow Prey Underwater
John Brueggen, General Curator
St. Augustine Alligator Farm, St. Augustine, FL 32080
Reprinted from the Bulletin of the Chicago Herpetological Society, Vol.38, No.2, February 2003.
The palatal valve, in the back of a crocodilian's mouth, is a unique adaptation that seals the throat off from both air and water. With this valve shut a crocodilian can grasp food underwater and not have the water flood past into the esophagus or glottis. Essentially the inside of a croco.dilian's mouth is outside its body. Crocodilians obviously prefer to keep this palatal valve closed while submerged, and come to the surface to swallow their prey. It is often assumed that crocodilians are unable to swallow food underwater, because of the overwhelming flood of water that would flow into their body. However, we have witnessed three species of crocodilian swallowing their food underwater. The first is a female freshwater crocodile, Crocodylus johnsoni, housed alone. On several occasions she has picked up pieces of meat from the bottom of the pool and proceeded to eat them without surfacing.
The second observation is of a female saltwater crocodile, Crocodylus porosus, housed with its mate. This female swallows both above the water and below, seeming not to have any preference for one over the other.
The most convincing observation has been a female false gavial, Tomistoma schlegelii. She is currently housed in a large exhibit with another female and a male. This exhibit affords visitors a complete underwater view of the entire pool exhibit, I witnessed her taking a piece of meat to the bottom of the pool and holding it. After about five minutes, she very deliberately partially opened her mouth, then opened her palatal valve, and quickly moved her head forward and swallowed the meat. She remained in a resting position on the bottom of the pool for another ten minutes. Since she had recently come to us from Audubon Zoo, I called the reptile staff there and asked if they had witnessed this behavior. They said that they had. Apparently the male Tomistoma at this facility was in the habit of stealing her food if she surfaced with it. I have witnessed her swallowing underwater on one other occasion. I believe the behavior is being extinguished by our training efforts, as our male does not have an opportunity to steal meat from the females.
I reluctantly included this subject in my talk at the 2002 Crocodilian Specialist Group (CSG) working meeting. I was just sure that the crocodilian experts from around the world were going to say that this was a very well known fact. But the only reference I found (Carpenter, 1928) is little more than guesswork on the part of the observer. Many CSG members came to me after the meeting and thanked me for mentioning this, as they too felt they had witnessed this behavior. Only one person said that they had actual video footage of a crocodilian swallowing underwater, but apparently it does happen with some frequency.
Literature Cited
Carpenter, C.D.H. 1928. Can crocodiles swallow their food under water? Nature [Lond.] 122:15
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