Which echinoderms use tube feet for breathing?

In echinoderms, the tube feet are versatile structures that can be adapted for various functions, including respiration. While the specific use of tube feet for breathing varies across groups, they are generally utilized for this purpose when located in areas where water flow is unimpeded and where they possess high oxygen uptake capabilities.1

The following groups utilize tube feet for respiratory functions:

• Echinoids: In regular echinoids, tube feet located on the upper side of the body near the anus serve respiratory and sensory functions. In irregular echinoids, which are burrowing animals, the tube feet are modified in various ways to facilitate respiration, as well as feeding and burrow construction.1
• General Adaptation: Across the phylum, tube feet may be adapted for respiration, among other tasks like feeding, sensory perception, or locomotion. Respiratory tube feet are characterized by their ability to facilitate high oxygen uptake.1

While other echinoderms, such as holothurians, have specialized respiratory structures like respiratory trees, the tube feet remain a key site for gas exchange in many species through thin areas of the body wall.12