Are Swimbladders of Fishes Really Derived From Lungs?
Amy McCune

Many living fishes can control their buoyancy by adding or eliminating gas from their swimbladder, which is basically a bag of gas that lies above the gut and below the vertebral column. While Darwin thought that swimbladders of fishes provided a nice transition between gill-breathing fishes and lung-breathing tetrapods, since the early 20th century, most (but not all) biologists have accepted the opposite hypothesis: swimbladders of fishes are actually modified lungs!

In this exploration we will delve into the structure, function and evolution of fish swimbladders. Hands on activities will include dissections of several different types of fishes which have functionally different kinds of swimbladders as well as attempting to achieve neutral buoyancy using physical models. Finally, we will discuss our current research to test the hypothesized common origin of swimbladders and lungs.