BREATH OF FRESH AIR

The image below is a photo of the exhibit panel. Following it is a transcript of the panel.

Photo of the panel from the exhibit.

Lungs evolved from a pocket on the gut of freshwater vertebrates

Lungs are breathing organs. They transfer oxygen from the air into an animal's blood, and remove carbon dioxide.

The earliest lung was a single pouch with a blood supply. It opened from the stomach-side of the gut in some freshwater vertebrates. Lungs allowed them to survive in stagnant, oxygen-poor water.

lunged vertebrates : aquatic vertebrates including fishes, lungfish, and land vertebrates

New features:

  • lungs , modified from a pouch off the gut, for breathing
  • bones , formed from cartilage forerunners, make up most of the skeleton

When? 400 million years ago to present

Lungs evolved from a pouch in the stomach of some aquatic vertebrates. In other aquatic vertebrates, later on, the same pouch migrated to the top of the body, above the spine, and evolved into a gas bladder. This air-filled sac helps to maintain neutral buoyancy in the water.

PICTURE CAPTIONS:

  • stomach
  • lung
  • gas bladder