Sea Urchin

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Respiratory: process related to respiration (the action of breathing). The respiratory system is responsible for movement of gases in and out of animals... more

Sea Urchin Tube Feet - Up Close

The tube feet that are not busy pulling the urchin along appear to be engaged in a slow dance. The feet below look a little blurry, because they were moving when the picture was taken. Notice how long and thin they are. Tube feet not only help the urchin move, they also are used to grasp food, and they are part of the respiratory or breathing system.

Sea urchin tube feet

Watch Sea Urchin Tube Feet in Action

The tube feet are part of the urchins water vascular system. They work like a hydraulic system. The urchin contracts its muscles to push water into the tube feet. This extends the feet outwards. When the muscles relax, the feet retract.


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Bibliographic details:

  • Article: Tube Feet
  • Author(s): CJ Kazilek
  • Publisher: Arizona State University School of Life Sciences Ask A Biologist
  • Site name: ASU - Ask A Biologist
  • Date published: December 23, 2009
  • Date accessed: June 12, 2024
  • Link:

APA Style

CJ Kazilek. (2009, December 23). Tube Feet. ASU - Ask A Biologist. Retrieved June 12, 2024 from

American Psychological Association. For more info, see

Chicago Manual of Style

CJ Kazilek. "Tube Feet". ASU - Ask A Biologist. 23 December, 2009.

MLA 2017 Style

CJ Kazilek. "Tube Feet". ASU - Ask A Biologist. 23 Dec 2009. ASU - Ask A Biologist, Web. 12 Jun 2024.

Modern Language Association, 7th Ed. For more info, see
Urchin tube feet
This is a scanning electron micrograph, or what is usually called an SEM image, of a sea urchin tube foot. You will notice the suction-cup end. Because the tube foot is retracted (pulled back), there are a large number of folds in the long part of the foot.

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