The Kid Should See This

How do sea stars walk and bounce?

When sea stars move around, how do they do it? How do starfish walk? This time-lapse-filled snippet from Science Magazine reveals that sea stars like the Forbes sea star (asterias forbesi) and the chocolate chip sea star (Protoreaster nodosus) can coordinate their “feet” or podia to bounce. In fact, “at least five species of sea stars bounce when startled or hungry, suggesting this behavior is widespread.” From Science Magazine:

Sea stars never move very fast, but bouncing is akin to a plodding human breaking into a full-tilt sprint, the researchers discovered. The animals rely on scores of tiny hydraulic “feet” that stick out underneath them. Usually, fluid fills and empties the podia at random to slide the starfish forward. For bouncing, the podia get in sync, with each third of them all filling at one time while the rest are swinging forward. To get a sense of how this is done, imagine having three legs and trying to run. One leg steps forward and the other two push to slide forward to keep up and the sea star moves much, much faster, with podia involved in one of every three steps.

starfish bouncing time lapse
Here’s a more clear time-lapse of a sea star’s tiny tube feet moving, as seen ⁣from underneath on aquarium glass:

Watch more echinoderm videos, including:
• Feather star swimming off the coast of Japan
• The Stomphia coccinea sea anemone can swim
• A Nine Armed Sea Star flips itself over
• Sea cucumbers are underwater vacuum cleaners
• What do sand dollars look like when they’re alive?
• The “secret world” below the Antarctic ice sheet

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