How Do Starfish Move?

As you meander along the seashore, do you ever think about the lifeforms around you? The crustaceans, birds, and ultimately, the enigmatic starfish, which also go by the name sea stars, a more accurate term. Why is that? Let's delve in. Unlike a fish, a starfish does not have a streamlined shape, nor does it have fins for swimming. In fact, its classification is echinoderm, a term stemming from Greek that translates to hedgehog skin, a diverse category of sea life that includes creatures like the octopus. Sea stars dwell in a variety of marine habitats, from sandy or muddy bottoms to rock-filled locales and shells, from tidal areas to deep waters. They are carnivorous creatures that nibble on smaller fauna, such as small crustaceans and molluscs. Though their movement on hard surfaces like rocks or sand is slow, they have a firm grip thanks to their tube feet, which create a vacuum with surfaces. In case you're wondering whether these marine inhabitants stay put in one place since they lack fins or legs, the answer is an emphatic no. This brings us to how sea stars move around, and to grasp this, we need to comprehend their anatomy. A critical component of movement in echinoderms, including sea stars, is the water vascular system. This system comprises canals inside the creature's body, filled with seawater, and the madriporite, a sieving plate situated at the starfish's lower surface. This plate filters water and transfers it to the stone canal beside it. The stone canal, named for its sturdy ring support, connects to the ring canal, known for its pentagonal shape. Extending from these five points are more canals that end in each foot of the sea star, the radial canals. The tube feet, double rows of them, lie in the radial canals and are connected via slender links called lateral canals. The canal system is crucial to the sea star's movement. It establishes hydraulic pressure, causing water to be drawn into the system through the madriporite. The water progresses through the stone canal, the ring canal, the radial canals, the lateral canals, and finally reaches the tube foot's swollen portion, called the ampulla. When the ampulla contracts, the water is propelled toward the podium, the thinner base, and its suckers, resulting in their elongation. The sea star can then reattach at a different point, resulting in a change of position. Once the sea star attains its desired spot, the ampulla relaxes, leading to the formation of suction cups. These form a vacuum, helping the creature to stick to the surface, effectively enabling it to be transported to a new location. This movement might be sluggish, but it's undeniably effective. Remarkably, the water vascular system is active around the clock, facilitating the movement of the sea star at any time, without requiring the force of a wave. So, as we can see, starfish or sea stars are yet another amazing species many simply overlook without realizing the wonder they inherently possess. If you enjoyed this video, we'd love to hear from you in the comment section. Your feedback not only supports us but also helps our channel reach more viewers and continue to grow.