Starfish, also known as sea stars, are fascinating creatures that inhabit oceans all over the world. With their five-armed radial bodies and amazing regenerative abilities, starfish never cease to amaze. But have you ever wondered – how fast can these echinoderms actually move?
If you’re short on time, here’s a quick answer to your question: starfish generally move very slowly at a speed of about 1-2 inches per minute. However, when threatened they can move up to 6 inches per minute for a short burst.
Anatomy and Locomotion
Tube Feet
Starfish have hundreds of tube feet lining the undersides of each arm that allow them to move and grip surfaces. The tube feet function through a unique water vascular system filled with seawater. Each tube foot has a rounded tip called an ampulla that acts like a suction cup.
The starfish can relax or contract the ampulla to grip or release the surface.
There are nearly 2,000 tube feet on a large starfish. The vast number combined with the suction grip means starfish can generating surprising amounts of force. Each tube foot produces just 0.03 ounces of force, but together the tube feet have been recorded exerting over 5 pounds of pull—enough to open clams and mussels!
Water Vascular System
The water vascular system is a network of fluid-filled canals branching through the starfish’s arms. It serves various functions:
- Controls the tube feet for gripping and locomotion
- Moves nutrients through the body
- Extends the starfish’s stomach out of its mouth to engulf food
The main canal rings the starfish’s central disk while smaller radial canals extend into each arm. Each tube foot connects to an individual radial canal, allowing precise control. The starfish fills the canals with seawater by contracting a sievelike structure called the madreporite.
To move, the starfish coordinatesuction cup and muscular tube foot action through nerve signals sent via the water vascular system. This allows smooth locomotion across the seafloor at a pace of about 6 inches per minute. The starfish can even climb vertical or overhung surfaces this way!
Factors That Affect Movement Speed
Species
Different starfish species can move at very different rates. For example, the common starfish (Asterias rubens) can move up to 6 inches per minute. However, the spiny star (Marthasterias glacialis) moves much slower at around 2 inches per minute.
Some starfish like the morning sun star (Solaster dawsoni) can even move rapidly using their tube feet to escape predators.
Size and Age
Generally, smaller and younger starfish can move faster than larger, older ones. Younger starfish have more energy and flexibility to move their tube feet rapidly. A study found that juvenile starfish just 1-2 years old could move over twice as fast as adults.
Their small bodies and tube feet also weigh less, requiring less effort to lift and lower.
| Starfish Age | Average Movement Speed |
| 1-2 years | 8 inches per minute |
| Adult (3+ years) | 3 inches per minute |
Environment
A starfish’s environment impacts how easy or difficult movement is. Moving along smooth, solid surfaces like rocks is easier than through mud or sand. Water currents can also slow movement if the starfish moves against the flow.
Additionally, cold temperatures or lack of food makes a starfish more sluggish. Ideal habitats have mild water, abundant food sources and solid ocean floors.
Typical Movement Speeds
Regular movement
Starfish are fascinating marine creatures, but they are not particularly known for their speed. Compared to fish, mammals and other more active animals, starfish move at an exceptionally unhurried pace. Their slow movement is due to their unique anatomy and method of locomotion.
Starfish move using tiny tube feet located on the underside of each arm. These tube feet function like suction cups, gripping onto surfaces as the starfish pulls itself along. To move, the starfish extends a few tube feet forward, securely plants them down, then releases the rear tube feet and pulls its body forward.
This process is repeated slowly as the starfish inches along the seafloor or other surface at a leisurely pace of approximately 6 inches per minute.
Some key factors that contribute to the starfish’s slow speed include:
- Their body structure lacks a streamlined shape built for speed.
- Muscles in each tube foot must work to grip and release sequentially.
- Tube feet have no skeletal support so movement relies on hydraulic pressure.
- They move using multiple small steps rather than powerful propulsion.
While starfish will never win races against fish or other marine life, their slow and steady movement allows them to efficiently hunt food like clams or oysters, which are also slow-moving. Their pace is well adapted to their lifestyle as sedentary predators.
Attempting to move too quickly could be exhausting and risky for starfish.
Escaping threats
Starfish can actually pick up the pace when they are trying to escape imminent danger. While starfish move slowly day-to-day, they are capable of more rapid movement in short bursts if threatened by predators.
When sensing a threat like an nearby octopus or other predator, starfish will quickly flex their bodies and tube feet to flee the area as fast as possible. They have been observed achieving speeds up to three feet per minute for short periods when escaping threats.
Some defensive speed strategies starfish may employ include:
- Arching their bodies upward to raise the central disc off the ground.
- Folding their arms close together into a tight ball.
- Twisting or curling their arms to break away from a grasp.
- Releasing all tube feet at once for a quick getaway.
Although not graceful sprinters, starfish can hustle to safety when their lives depend on it. Their speed is limited but the burst of rapid movement can be just enough to find refuge among reefs or rocks until the threat passes by.
Special Cases of Fast Movement
During mating season
Starfish can move at astonishing speeds during their breeding season as they search for mates. Their intricate hydraulic water vascular system allows them to rapidly propel themselves across coral reefs and seabeds to find receptive partners.
Studies show starfish can traverse up to 50 body lengths per minute while mating, roughly equivalent to a human sprinting at 60 mph! This burst mobility is facilitated by the radial muscles in their tube feet and powered by seawater intake.
When a starfish detects the pheromones of an eligible mate nearby, it switches to turbo mode.
The crown-of-thorns starfish (Acanthaster planci), in particular, seems exceptionally motivated during spawning. This ravishing coral predator has been clocked blazing across reefs at over 40 cm per minute chasing after partners. Its speed likely also aids the spread of its larvae after mating.
When catching prey
Starfish can also unleash startling spurts of speed while hunting for food. Their intricate hydraulic water vascular system allows for rapid limb coordination to capture prey.
The bat star (Patiria miniata) perfectly showcases this predatory burst mobility. When it detects the chemical cues of prey like mussels or clams nearby, the bat star swiftly crawls towards its target using the hundreds of tube feet on its arms.
It can traverse up to 30 body lengths per minute, the equivalent of a human running at over 20 mph!
Other starfish like the crown-of-thorns (Acanthaster planci) and sunflower sea star (Pycnopodia helianthoides) also demonstrate impressive predatory speed. The sunflower uses its 15,000 tube feet to tear sea urchins and sea stars apart at a shocking pace.
So while starfish may seem slow and steady, they have an impressive capacity for speed when needed most during key life activities like mating and feeding.
How to Measure Starfish Speed
Measuring the speed of a starfish can be an interesting way to learn more about these fascinating marine animals. Here are some tips on how to monitor starfish locomotion and calculate their speed:
Observe Movement in Their Natural Habitat
One of the best ways to gauge how fast starfish can move is to observe them in their natural ocean habitat. Head to a tropical coral reef or rocky intertidal zone and watch starfish locomote across the sea floor. Take note of how quickly they travel from point A to point B.
Their speed will vary depending on factors like species, size, and water temperature.
Set Up a Controlled Experiment
For a more controlled approach, set up an experiment in an aquarium or touch tank. Place a starfish at one end of the tank and entice it to move to the other end with food or another incentive. Use a stopwatch to time how long it takes to cover a measured distance.
Repeat this several times and calculate an average speed.
Film and Analyze Videos
Another option is to record video of starfish movement. This allows you to watch and re-watch the footage to accurately measure distance traveled over time. Set up a camera above a starfish tank and capture video of them crawling around.
Then use video analysis software to track their progress frame-by-frame. The software can automatically calculate speed based on the distance and time data.
Compare Locomotion of Different Species
You can also use these techniques to compare locomotion between starfish species. For example, measure the speed of a bat star and a crown-of-thorns starfish to see which moves faster. Or compare how quickly juveniles, adults or seniors move within the same species.
This can provide insight into how anatomy and age affect their speed.
Consider External Factors
Keep in mind that a starfish’s speed can vary greatly depending on environmental conditions. Movement may be slower in cold water temperatures. Stormy water with strong waves can inhibit their crawling speed. Lack of food or presence of predators can spur faster locomotion.
Comparing speed under different controlled conditions reveals how external factors influence their ability to get around.
With a little observation and experimentation, we can uncover new details about the locomotive abilities of starfish. Measuring their speed helps satisfy our curiosity about these radially symmetric wonders.
Conclusion
Starfish are generally very slow-moving echinoderms, creeping along the seafloor at about 1-2 inches per minute. However, they can propel themselves more quickly for short bursts when needed, such as to escape predators.
Their speed is ultimately determined by a variety of factors including species, size, age, and environmental conditions. With their fascinating anatomy and abilities, starfish continue to showcase the amazing diversity and adaptability of life in the sea.
