The Crown-of-Thorns Starfish & a Genetic Trojan Horse

A Crown of Thorns Starfish in the waters of Fiji
Crown-of-Thorns starfish near Qamea Island in Fiji. Photographer: Matt Wright Date: October 12, 2005 Camera: Canon PowerShot S410

The Crown-Of-Thorns Starfish may not look like much, but their impact is inarguable. They feed heavily on corals essential for building reefs, the marine equivalent of a metropolis. When these starfish have a boom in their population, the result is a significant loss of live coral. The damage has a higher impact on the reef’s health and resilience than bleaching and disease combined. The incredible diversity of other species dependent on that coral face sharp declines in turn. And it’s not just wild lives that are affected. These reefs act as natural barriers or shields protecting coastal cities. Without those barriers, coastal plants and beaches are at risk. Plus, reef-dependent industries face significant losses. 

The Crown-Of-Thorns Starfish is extremely successful at reproducing. They gather and spawn in mass which makes them highly difficult to control. To save the reefs, scientist are looking for creative solutions. The trick is limiting the population without affecting other species. Whatever the method of control is needs to be species-specific.

Crown-Of-Thorns Starfish rely on detecting chemical signals from prey, predators, and other starfish. This is especially important during reproduction. It is believed that chemical signals released as plumes in the water trigger the starfish to form large groups. It is these large groups that provide the best chance for successful reproduction.

If scientists can identify the genes linked with those chemical signals, they can try to hijack them. To start, researchers compared the genomes of Crown-Of-Thorns Starfish from the Great Barrier Reef in Australia and off the coasts of Okinawa, Japan.

As it turns out, they are nearly identical. Enough to be considered the same species despite the geographic distance. This means a genetics-based solution designed for one location should work across their entire range. The researchers were able to narrow the search down to proteins which caused the largest groupings. To be the most impactful, they needed a signal that attracted both active and sedentary starfish. The search was an astounding success. The next step is developing a protein mimic. This mimic can be used to lure masses of the starfish for collection and removal, rescuing reefs from Australia to Japan.

This data has the potential to be a powerful tool for studies on the causes of Crown-Of-Thorns Starfish outbreaks and revolutionary for managing these and other marine pests.

Hall, M., Kocot, K., Baughman, K. et al. The crown-of-thorns starfish genome as a guide for biocontrol of this coral reef pest. Nature 544, 231–234 (2017). https://doi.org/10.1038/nature22033

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