Britannica
Sources used in this answer
How do grebes move their feet differently while swimming at the surface and underwater?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
Grebe
Slavonian, or horned, grebe (Podiceps auritus)
Grebes exhibit distinct foot movements depending on whether they are swimming at the surface or submerged underwater:
- Surface Swimming: While on the surface, grebes typically propel themselves using alternate strokes of their feet.1
- Underwater Swimming: When submerged, grebes move their feet simultaneously.1
To maximize efficiency during these movements, grebes utilize a specific rotation mechanism. Between the recovery and power strokes, the feet are turned 90 degrees to ensure the broad side of the foot is used for propulsion. Just before the recovery stroke begins, the feet are rotated in the opposite direction to reduce resistance.1