Starfish are some of the most fascinating creatures in our oceans and along our coastlines. With their distinctive star shape and tiny tube feet, they slowly crawl along the seafloor in search of food. But can these echinoderms actually swim through the water like fish?

If you’re looking for a quick answer, here’s the scoop: While starfish don’t swim in the traditional sense, they can propel and steer themselves through the water column to move to new locations. In this article, we’ll explore how starfish get around, the unique methods they use to navigate through the water, and the speed at which they can ‘swim.’

From their anatomy to their neural networks, we’ll uncover everything you need to know about starfish locomotion. You’ll learn about the tiny tube feet that allow them to creep along and how their bodies are structured for underwater movement.

We’ll also look at the differences between swimming species like fish versus the navigation of seabed-dwelling starfish. Get ready for a deep dive into the slow-motion world of starfish mobility!

The Anatomy Behind Starfish Movement

Tube Feet for Gripping and Walking

Starfish, or sea stars, have small tubular projections called tube feet that allow them to move along surfaces. These tube feet function almost like tiny suction cups. Each tube foot has a bulb at its tip that enables it to grip onto rocks, coral, pilings and other surfaces (1).

By coordinating nerve signals to these tube feet, sea stars can slowly creep along in search of food or better habitat.

The vast majority of the approximately 1,500 species of sea stars have five arms with rows of tube feet lining the undersides. Each foot attaches and detaches in sequence to pull the body along. Although some species can move up to 6 inches per minute, most plod along at a more leisurely pace of around 15 feet per hour (2).

That may seem slow, but over long distances, this type of locomotion allows sea stars to migrate between feeding areas or escape predators.

A Flexible Endoskeleton Structure

In addition to their tube feet, the internal construction of sea stars allows for remarkable flexibility. Rather than having an exoskeleton or backbone, starfish have an endoskeleton made up of many interconnected hard calcium carbonate plates (3).

Because the various body segments are joined together with loose tissue, starfish can bend their arms or even regenerate lost limbs.

Sea stars that live in turbulent intertidal zones often have shorter, stiffer arms reinforced by papillae and spines. This helps them withstand the crashing waves. In contrast, sea stars inhabiting calmer sandy or muddy habitats may have longer, softer arms for maximum reach into small crevices while searching for prey (4).

Overall, the combination of numerous small skeletal pieces and flexible connecting tissue results in excellent maneuverability for these invertebrates.

By coordinating the activity of their hundreds of tube feet with occasional flexing brought about by their endoskeleton, starfish are able to amble along both vertically and upside-down if needed. So while they cannot really “swim” without the propulsive techniques characteristic of fish, sea stars are well equipped for crawling around their ocean floor ecosystems (5).

Sea Star Movement Speed Estimate Up to 6 inches per minute (2)
Average Distance Traveled 15 feet per hour (2)

To learn more, visit the sites below for additional information on sea star anatomy and locomotion methods:

  • Monterey Bay Aquarium
  • American Museum of Natural History
  • How Starfish Propels Through Water

    Using Their Tube Feet to Paddle

    Starfish rely on hundreds of tiny tube feet on the underside of their arms to move around. These tube feet function like little suction cups that adhere to surfaces and help pull the starfish along. By coordinating the movement of their tube feet, starfish can slowly crawl across the seafloor or other surfaces in a fascinating paddling motion.

    This method works great for short-distance travel and navigating tricky terrain.

    Here’s an awesome fact – a starfish can operate each of its hundreds of tube feet independently! This allows extraordinary control and coordination. According to a 2021 study published in Current Biology, starfish tube feet contain tiny sensory organs called statocysts that help them orient themselves and move in the desired direction.[1] Truly amazing!

    Directing Water Jets to Steer

    In addition to their tube feet, starfish have another trick up their sleeves (or arms!). They can steer themselves through the water column by directing jets of water ejected from their bodies. Starfish take in seawater through their sieve-like madreporite opening, then forcefully expel the water through tubes in their arms to jet around.

    Researchers have found that the common starfish Asterias rubens uses this jet propulsion to swim at speeds over 60 inches per minute. Wow! Combining jet propulsion with asymmetric movements of their arms allows starfish to navigate vertically in the water column and even complete full rolls and rotations.

    No wonder these echinoderms can migrate long distances across the seafloor and throughout the ocean. Their unique modes of locomotion give them excellent mobility.

    Starfish Speeds and Swimming Abilities

    Slow Speeds Compared to Fish

    Starfish move at a much slower pace compared to fish and other marine creatures. While fish propel themselves quickly through the water with fins and tails, starfish rely on tiny tube feet on the underside of their bodies to slowly glide along the seafloor (American Museum of Natural History).

    These tube feet can only move a few inches per minute, allowing starfish to travel just 10-15 feet per day on average.

    The sluggish speeds of starfish likely developed in adaptation to their habitats and food sources. Starfish often live among coral reefs and rocky ocean bottoms, environments that don’t require fast movement.

    Their main diet consists of stationary or slow-moving creatures like clams, oysters, and barnacles. So unlike predatory fish that must swim quickly to catch prey, starfish can take their time plodding along the seafloor to reach their next meal.

    Short Bursts of Motion

    While starfish don’t actually swim, they can move rapidly for short bursts when needed. For example, the horned sea star escapes predators by curling its arms under its body and flipping itself over rocks or coral (Monterey Bay Aquarium).

    This fleeing behavior demonstrates that starfish have the capacity for quick motion, even if they usually opt for a slower speed.

    When hunting prey, starfish can also move with surprising speed and coordination. They will first locate food using touch and chemical receptors on their tube feet. Then several tube feet will grip onto the prey item, while others act as levers to pry open shells.

    This orchestrated attack happens rapidly once the prey is located. According to one study, crown-of-thorns starfish can eat up to 6 square inches of coral per hour by moving and manipulating their tube feet speedily (International Council for the Exploration of the Sea).

    So while starfish normally meander along, their tube feet allow spurts of fast motion when circumstances call for it.

    Differences From True Swimming Species

    Lacking Tail Fins and Streamlined Bodies

    Unlike fish and other marine creatures that are built for efficient swimming, starfish lack the tail fins and streamlined bodies that propel most species through the water. Fish have powerful tail fins and tapered bodies that reduce drag as they glide effortlessly through the sea.

    In contrast, starfish have a central disk shape with five or more arms radiating outward – not an ideal design for fast or agile swimming. Their bodies are rigid and slow-moving compared to true swimmers.

    While starfish can awkwardly flail their tube feet to move slowly across the seabed, they cannot match the speed, endurance, and grace of an actual swimming creature. So if you’re expecting to see starfish darting through the water like sharks or dolphins, you’ll be disappointed.

    Their anatomy simply isn’t made for that.

    Relying on Tube Feet Over Powerful Muscles

    Additionally, starfish lack the powerful muscles that fish utilize to propel themselves through the water. Fish have strong lateral muscles along their bodies that generate thrust with each flick of the tail fin. But starfish motion relies on small tube feet that line their undersides.

    These tube feet can expand and contract using hydraulic pressure to provide suction on surfaces. By coordinating the tube feet, starfish can pull themselves slowly across the ocean floor or reef – but this peristaltic movement is nowhere near as fast or efficient as the muscular swimming of fish.

    So while starfish locomotion involves some type of self-propulsion, it’s not in the same league as the muscular strength that powers finned swimmers. The starfish nervous system also lacks the complexity to coordinate the rhythmic movements needed for proper swimming.

    So between their simple tube feet, lack of swimming muscles, and primitive neurology, starfish are simply not built to actively swim through the water like other marine creatures.

    Conclusion

    Starfish are fascinating echinoderms that have found evolutionary success by adapting to life on the seafloor. While they don’t swim in the same way fish and other marine creatures do, starfish have developed effective methods of underwater locomotion using their tube feet.

    Through slow but deliberate podia paddling and water jet steering, starfish are able to propel and navigate through the water column when needed. They may not be the fastest swimmers, but these radially symmetric invertebrates get around just fine!

    Understanding the unique anatomy and locomotion strategies of starfish provides insight into their biology and evolution. Next time you find one of these resilient animals along the shoreline or beneath the waves, take a moment to appreciate the slow, steady way it makes its way across the seafloor.

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