Alligators use buoyancy tanks, according to an article in EurekAlert 13 March 2008 and ScienceNOW 14 March 2008.

Alligators draw air into their lung using rib muscles and a large muscle called the diaphragmaticus which runs lengthways along its body cavity connecting the pelvis to the liver and lungs. T. J. Uriona of Utah noted that the diaphragmaticus in alligators worked in a similar way to a muscle that swimming frogs use to change the distribution of air in the lungs, using the shift in buoyancy to manoeuvre under water. As alligators are particularly good at moving through water with very little movement of limbs and tail, he set out to see if alligators used the same means of manoeuvring. Uriona attached electrodes to the muscles that move air in and out of the lungs and studied their activity while the animals were diving. He found the muscles were active, even though the animals were holding their breath.

When an alligator was diving, the muscles pulled the lungs down, shifting the buoyancy towards the tail. When the animal was returning to the surface the muscles pushed the lungs upwards, and when the animal rolled in the water the muscles on one side were active – moving the buoyancy to one side. Uriona commented: “Until now, it was believed the diaphragmatic muscle evolved to help them breathe and run at the same time.  Showing they are actually using it to move around in water gives an alternative explanation for why the muscle evolved.”

Colleen Farmer, a biologist at University of Utah commented: “special muscles that manipulate the position of the lungs – and thus the centre of buoyancy – may be an underappreciated but important means for other aquatic animals to manoeuvre in water without actively swimming.” Other animals use buoyancy shifting including crocodiles, African clawed frogs, some salamanders, turtles and manatees. According to Farmer it must have been “incredibly important or you would not see it evolve repeatedly.” Uriona and Farmer suggest that the diaphragmatics developed from a muscle originally used in walking that went through two steps of evolution, first to attach it to the lungs so that it could be used to assist swimming, and then a re-wiring process so that it was used for breathing as well.

Editorial Comment: In spite of the numerous references to evolution, this study is a good piece of practical real world biology that does not need the theory of evolution. The real science in this study is the observation of how swimming animals move and the experiment with the electrodes in alligator muscles. These revealed a fully functioning system of muscles and nervous system control. The speculations about two step evolution in alligators and repeated evolution in different kinds of animals are based on a prior belief in evolution that has been applied to the scientific observations, not derived from them. The fact that fully functioning buoyancy assisted swimming is found in many kinds of animals is evidence for the creation of separate kinds of fully functioning animals, as described in Genesis, rather than repeated chance random evolution.

Evidence News 23 April 2008

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