Sea stars may appear to glide slowly across the seabed, but their movement is the result of a remarkably sophisticated system. Unlike animals with a centralised brain, sea stars rely on hundreds of flexible tube feet working together to crawl, climb and even move upside down. New research now sheds light on how this coordination happens—and how sea stars adapt their movement to changing physical demands.
They can have up to 40,000 feet, produce millions of offspring and eat with their stomachs outside their bodies. Sounds like something from a sci-fi film? You probably see them on every dive you make! Christian Skauge and Peter Symes provide 12 intriguing insights into sea stars.
Sea stars (or starfish—but they are not fish) are a common sight for divers, as they occur in all the world’s oceans, from tropical reefs to the polar seabed. But how much do you know about these slow-moving predators?
They can have between five and 30 arms, arranged in radial symmetry, and they lack blood, a brain, a heart and other vital organs. Yet they have conquered the world’s oceans. Here are some interesting facts about starfish:
The sunflower sea star was once a common sight along North America's Pacific coast. Although it is now an endangered species, scientists are hailing it as a potential saviour of the region's threatened kelp forests.
Recent research reveals its crucial role in controlling the population of kelp-eating urchins, thus offering a glimmer of hope for these vital marine ecosystems.
A well-preserved fossil dating back 480 million years is being used by researchers at the University of Cambridge to decipher the origins of the modern-day starfish.
Named Cantabrigiaster fezouataensis, the fossil was discovered in Morroco's Anti-Atlas mountain range. Frozen in time for 480 million years, the fossil yields features that are similar to both sea lilies and modern-day starfish.
Outbreaks of crown-of-thorns starfish (CoTS) are bad news for coral reefs, so it is essential that they are detected and dealt with as soon as possible.
But detecting an outbreak in its early stages is not easy. What’s more, they sometimes hide under coral plates, while the younger ones can be as small as just a few millimetres.
To counter this, the researchers at the Australian Institute of Marine Science (AIMS) developed a new test to detect the presence of the starfish on coral reefs.
Most divers take a quick look at the shapes and varieties of feather stars, but usually pass on by, in search of other interesting subject matter. However, there is more to them than meets the eye!
Crinoids, or "feather stars" as they are commonly known to the scuba diving community, are echinoderms, members of the phylum Echinodermata, meaning "spiny skin," which includes many well-known species like sea stars, sea urchins and brittle stars.
In June X-Ray Mag correspondent Scott Bennett reported on a "Mysterious Disease Decimating Oregon Sea Star Populations". He wrote "a mysterious disease affecting sea stars has erupted along the Oregon coast. Sea star wasting syndrome causes the creature’s body to disintegrate, ultimately leading to death. Up to half or more of the creatures along the coast have been infected in just a matter of weeks.
Developed by roboticists from Queensland University of Technology, this is the world's first robot designed to search and destroy (so to speak) the dreaded crown-of-thorns starfish (COTS). It does this by seeking them out, identifying them and then administering a lethal injection of bile salts.
Its creators, Dr Matthew Dunbabin and Dr Feras Dayoub, equipped the robot with GPS, stereoscopic cameras for depth perception, thrusters to improve stability, pitch-and-roll sensors as well as the pneumatic injection arm.
The Ochre starfish Pisaster ochraceous is most commonly found in the Northeastern Pacific, where, at low tide, it can often be seen in tidal pools and sitting tucked away in rock crevices.
During low tide, it is exposed to the air and cannot move until it is submerged again at high tide. If it is also exposed to the sun, it can suffer heat stress.
Pisaster ochraceous can be found on wave-washed rocky shores, from above the low-tide zone to 90 m in depth. Because they can live in shallow water they need to survive in these living conditions, including strong surges, big temperature changes, dilution by rainfall, and dessication. Pisaster ochraceous is very resistant to dessication and it can tolerate a loss of thirty-percent of its body weight in body fluids.