How Does A Starfish Move?

Starfish (sea stars) move using thousands of tiny tube feet located on their underside. These tube feet are powered by a water vascular system that uses hydraulic pressure to extend and retract the feet, allowing the animal to crawl slowly across surfaces.

During your long walks on the beach, have you ever taken a step back and noticed the creatures around you? The crabs, the birds, and most importantly, the starfish? If not, then you’ll certainly take note after reading this article! Not only does the starfish have a gimmicky name, but it’s also a pretty enigmatic creature! Few animals are clever enough to leverage water to their advantage like a starfish. How? Let’s find out!

The means of locomotion for a starfish is through their tube feet. A starfish has thousands of these tube feet on its lower surface. When water enters the canals inside the body of a starfish, it eventually reaches these feet. A series of contraction and relaxation procedures take place, which displaces the animal from one place to another. Pretty cool! Now, let’s take a more in-depth look to understand this all a bit better!

What Is A Starfish?

Starfish are also known as sea stars. Interestingly, ‘sea star’ is also a more correct way to refer to this animal, because a starfish is nothing like an actual fish! It doesn’t have a streamlined shape or any fins for swimming. Scientifically, a starfish is actually an Echinoderm. The term echinoderm comes from the Greek language, which means “hedgehog skinned”. It is an entire phylum of zoological classification, and several other well-known animals fall under this category, such as sea urchins, sea cucumbers, and brittle stars!

Sea stars are free-living marine animals that are often found on sandy or muddy bottoms, crawling over rocks and shells. From tide marks to deep waters, these creatures are found everywhere. Most sea stars are carnivores, meaning that they feed on other smaller animals, including small crustaceans and mollusks, though some species are omnivorous and also consume algae. On a hard surface, such as rocks or sand, sea stars move very slowly. They cling firmly to these surfaces with their tube feet, which secrete a natural, glue-like adhesive (more on that shortly).

What Is The Water Vascular System In A Sea Star?

Now, if a sea star doesn’t have any fins or legs, does it just remain attached to one place forever? Well, the obvious answer is no! So how does movement take place? For that to be understood, we need to look at the general anatomy of a sea star. Don’t worry; sea stars are not very complex organisms. As such, they don’t have elaborate body systems like us!

The water vascular system is primarily responsible for locomotion in all Echinoderms, including the sea star. It is a system of canals inside the body of the animal that contain seawater. The water vascular system also contains the madreporite, which is a sieve-like plate located on the aboral (upper) surface of the sea star. It has very minute pores that filter the water and transfer it to the stone canal, which lies beside it.

The stone canal has that name because hard rings support it. This canal then connects to the ring canal, which is a circular canal encircling the mouth. From this ring canal, five canals arise and terminate into each foot of the sea star. These are called the radial canals. Now comes the star of the system, the tube foot. Two double rows of tube feet line the radial canals, and are connected to the canals via tenuous links. These connections are called lateral canals.

This whole system of canals might sound a little intimidating, but the whole picture becomes clear once you consider the movement of water!

How Does The Sea Star Move?

The water vascular system is critical to the movement of a sea star. It helps in setting up hydraulic pressure, which pulls in the water. All the tube feet have a swollen structure called the ampulla, which end at a thinner base that forms the podium. The podium ends in a flattened, disc-shaped tip that grips the ground.

When the water is taken inside this system through the tiny pores of the madreporite, it travels through the stone canal, the ring canal, the radial canals, and finally, the lateral canals. This then reaches the ampulla, where the water is maintained at all times. When the ampulla contracts, it forces the water towards the podium, which results in their extension. This helps in detaching an arm of the sea star from the surface. The animal may then choose a different point of attachment, which brings about another displacement in its position.

After it reaches the spot where it wants to settle, the tube feet anchor down once more. For a long time, people assumed they did this purely by suction, like rows of tiny suction cups pressing against the surface. The truth turns out to be far more clever! Each tube foot carries what biologists call a “duo-gland” system: one set of cells secretes a protein glue that bonds the foot to the surface, while another set releases a chemical that dissolves that bond the instant the animal wants to let go. This is why a sea star can hold just as tightly to rough, pitted rock as to smooth glass, where simple suction would slip, and why every step leaves behind a microscopic “footprint” of dried adhesive. Suction plays only a small supporting role. So even though the motion is slow, the grip is remarkably secure, and the whole system is wonderfully effective!

How Fast Can A Starfish Move?

If you have ever watched a starfish clinging to a rock, you would be forgiven for thinking it wasn’t moving at all! Most sea stars are famously slow, creeping along at just a few centimeters per minute. They are in no rush, and they rarely need to be.

A handful of species, however, are surprisingly speedy. The sunflower sea star (Pycnopodia helianthoides), a giant carrying up to 15,000 tube feet, can travel at roughly one meter (a little over three feet) per minute, which once earned it the title of the fastest starfish on record. Quicker still is the sand star (Luidia foliolata), which can scoot across the seafloor at over nine feet (close to three meters) per minute when it needs to flee a predator. For an animal with no brain and no legs, that is genuinely impressive!

Why such a wide range? It comes down to how many tube feet an animal has and how well it coordinates them. The more tube feet that swing in synchronized waves, and the better the animal is at lifting parts of its body clear of the ground, the more distance it covers with every push.

Can Starfish Swim, Or Only Crawl?

Here is a question that stumps a lot of beachgoers: since a starfish lives in the ocean, can it swim? The short answer is no. Adult sea stars are bottom-dwellers through and through. With no fins, no tail, and no streamlined body, they cannot propel themselves through open water the way a fish does. Instead, they crawl steadily along the seafloor, rocks, and coral using the very tube feet we have been describing.

There is one charming exception, though. A starfish begins life as a tiny larva that drifts and swims freely among the plankton, wafted along by ocean currents and rows of microscopic hairs called cilia. Only once it settles to the bottom and transforms into the familiar five-armed shape does it trade swimming for its slow, crawling adult lifestyle. So yes, a starfish can swim, but only as a baby!

How Do Other Echinoderms Move?

Remember that our starfish belongs to a much larger family, the echinoderms, which also includes sea urchins, sea cucumbers, brittle stars, and feather stars. They all share that same ingenious water vascular system, yet evolution has handed each group its own way of getting around.

Brittle stars are the sprinters of the bunch. Unlike the sea star, they barely use their tube feet to travel at all. Instead, they row with their long, snake-like arms, one arm reaching forward while the others push off in coordinated strokes, jerking the body along in surprisingly quick bursts. This rowing gait makes brittle stars the fastest-moving echinoderms of all.

Sea urchins take a different tack, pairing their tube feet with their movable spines. The spines work like tiny stilts and levers that help the urchin push along, climb, and flip itself upright, while the tube feet grip and pull. Between the two, an urchin can head off in any direction without ever turning around.

Sea cucumbers mostly inch forward on rows of tube feet, but many also ripple the muscles in their soft body wall to creep along, rather like a slug or an earthworm. A few deep-sea species can even lift off and swim short distances by undulating their bodies. Feather stars, for their part, swim with surprising grace by sweeping their feathery arms up and down, then simply crawl across the reef when they would rather stay close to home.

So while the humble tube foot steals the show for our sea star, it is really just one of many clever solutions echinoderms have evolved for a life on the move!

Conclusion

An interesting thing to note is that the water vascular system is functional at all times. The water inside the canals and the ampulla of the tube feet are present 24/7. Thus, a sea star can move from one place to another whenever it wants, and doesn’t need to wait for a wave of water to change location.

Recent research has also highlighted how important sea stars are to ocean ecosystems. Since 2013, sea star wasting disease has devastated populations along the Pacific coast of North America, killing billions of individuals. By 2025, however, scientists at the University of Washington developed a groundbreaking captive breeding program, and captive-raised sunflower sea stars are now being released into the wild, offering hope for the recovery of this critically endangered species.

There are some things that sit right in front of our eyes, but we never really appreciate how wonderful they truly are. Sea stars certainly fit in that category!