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Starfish How does a starfish move?

Trace seawater through the water vascular system as tube feet grip, pull, coordinate movement, and help a sea star recover and regenerate.

lessons

~10 min

to learn

🔬 Science

subject

Adults

level

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What you’ll learn

A sea star walks on its undersideIdentify tube feet and explain how their distributed grips create traction and coordinated crawling.A sea star walks with many small underside feet rather than fins or jointed legs.
Water pressure powers each footTrace seawater from the madreporite through canals and ampullae to an extending tube foot.The water vascular system transmits fluid pressure to hydraulic feet.
A sea star can recover and regrowExplain how tube feet right an overturned sea star and how species-dependent regeneration restores lost movement structures.Distributed traction aids recovery, while controlled regeneration can rebuild an injured arm.

Questions this course answers

Which structures provide most of a sea star's traction?

Tube feet extend from the water vascular system and attach to the seafloor.

Put the hydraulic movement sequence in order.

The water vascular system transmits fluid pressure from its entry point to each foot.

Why can a sea star move without jointed legs?

The animal distributes movement across hydraulic feet rather than swinging a few rigid limbs.

What happens when an ampulla contracts?

Ampulla contraction shifts fluid into the foot and helps extend it.

Why does regeneration not mean every loose arm becomes a new sea star?

A separated arm may regenerate in some species, but a complete new animal requires the right surviving structures.

How can tube feet help an overturned sea star?

Feet can establish grips and use arm leverage to restore the mouth-down position.

Grounded in trusted sources

NOAA Ocean Service, Are starfish really fish?, https://oceanservice.noaa.gov/facts/starfish.html
Animal Diversity Web, Asteroidea, https://animaldiversity.org/accounts/Asteroidea/
Animal Diversity Web, Asterias rubens, https://animaldiversity.org/accounts/Asterias_rubens/
World Asteroidea Database, WoRMS, https://www.marinespecies.org/asteroidea/
Wikimedia Commons MediaWiki API, https://commons.wikimedia.org/w/api.php

Every Wunder lesson is built from real, reputable sources — never invented.

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