Starfish

The largest sea star in the world, the sunflower sea star is a predatory sea star usually with 16 to 24 limbs called rays.
The largest sea star in the world, the sunflower sea star is a predatory sea star usually with 16 to 24 limbs called rays.

Sea stars can help to restore kelp forests

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.

The fossil in question: Cantabrigiaster fezouataensis from the Lower Ordovician (Tremadocian) Fezouata Shale, Zagora Morocco
The fossil in question: Cantabrigiaster fezouataensis from the Lower Ordovician (Tremadocian) Fezouata Shale, Zagora Morocco

Starfish-like fossil holds clues to evolutionary past

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.

The crown-of-thorns starfish can sometimes be hard to spot using traditional survey methods.

New test to detect crown-of-thorns 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.

Sick Starfish Syndrome, Laura James, The Seattle Times, Rosemary E Lunn, X-Ray Mag
A dying Pisaster ochraceus sea star in the waters off West seattle dangles by its tentacle

Sick Starfish Linked To Warming Ocean

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.

The two creators of the COTSbot.

Fight against crown-of-thorns starfish goes hi-tech

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.

Ochre Starfish wait out the low tide on a rocky shore off Vancouver Island
Ochre Starfish wait out the low tide on a rocky shore off Vancouver Island

Ochre starfish have a cooling system

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.