Looking for the legacy site? Click here

How did ancient fish make the evolutionary jump from gills to lungs?

Gerett

Grade Level

9

Answered by

Alex Brashears

That's a great question. Swim bladders and lungs are similar organs, although they are used for different things and found in different groups of fish. They both develop from a location in the upper throat called the pharynx, they both are used to manipulate gases, and they both have a good blood supply. However, the lung is used for breathing, and, besides being found in land vertebrates, is also found in a few groups of fish like lungfish, which likely were the ancestors of land vertebrates.

The swim bladder, on the other hand, is used to control buoyancy, and it is found in all other bony fishes. It is basically an inflatable bag. Fish use the swim bladder to control their buoyancy by filling it with oxygen from their gills using a gland called a gas gland. This increases the volume of the bladder and pushes the fish toward the surface of the water.

Strangely, some fish also use their swim bladders to breathe. These fish live in muddy waters that are low in oxygen, and they have a tube that runs from the swim bladder to the gut, so that when they gulp air from the surface they can push the gas into the swim bladder.

Darwin believed that lungs evolved from gas bladders, but the fact that fish with lungs are the oldest type of bony fish, plus molecular and developmental evidence, points to the reverse – that lungs evolved before swim bladders. Gills were present in the earliest fish, but lungs also evolved pretty early on, potentially from the tissue sac that surrounds the gills. Swim bladders evolved soon after lungs, and are thought to have evolved from lung tissue.


Barracuda image released to the public domain by author, Laban712

You may need to edit author's name to meet the style formats, which are in most cases "Last name, First name."
https://askabiologist.asu.edu/top-questions/test-question

Bibliographic details:

  • Article: How did ancient fish make the evolutionary jump from gills to lungs?
  • Author(s): Dr. Biology
  • Publisher: Arizona State University School of Life Sciences Ask A Biologist
  • Site name: ASU - Ask A Biologist
  • Date published: 25 Jul, 2016
  • Date accessed:
  • Link: https://askabiologist.asu.edu/top-questions/test-question

APA Style

Dr. Biology. (Mon, 07/25/2016 - 13:22). How did ancient fish make the evolutionary jump from gills to lungs?. ASU - Ask A Biologist. Retrieved from https://askabiologist.asu.edu/top-questions/test-question

American Psychological Association. For more info, see http://owl.english.purdue.edu/owl/resource/560/10/

Chicago Manual of Style

Dr. Biology. "How did ancient fish make the evolutionary jump from gills to lungs?". ASU - Ask A Biologist. 25 Jul 2016. https://askabiologist.asu.edu/top-questions/test-question

MLA 2017 Style

Dr. Biology. "How did ancient fish make the evolutionary jump from gills to lungs?". ASU - Ask A Biologist. 25 Jul 2016. ASU - Ask A Biologist, Web. https://askabiologist.asu.edu/top-questions/test-question

Modern Language Association, 7th Ed. For more info, see http://owl.english.purdue.edu/owl/resource/747/08/

Be Part of
Ask A Biologist

By volunteering, or simply sending us feedback on the site. Scientists, teachers, writers, illustrators, and translators are all important to the program. If you are interested in helping with the website we have a Volunteers page to get the process started.

Donate icon  Contribute