Beachcombers, scuba divers and snorkelers typically avoid urchins. If you step on one or accidentally bump into it, your skin can be punctured by the creature’s needle-like spines. Once under the skin, the spines are difficult to remove.
Florida Keys marine biologist Jim Brittsan, however, is excited by the round spiny creatures. As he explains, a healthy urchin population in the Caribbean is vital to the health of coral reefs.
Jim, 27, works with multiple coral restoration organizations throughout the Keys. Beginning as a self-funded project, he now has financial support from the state of Florida and is raising urchins in the wild with hopes of reintroducing them to Florida’s coral reef.
Urchins are important to the reefs because they eat algae. Out-of-control algae growth kills coral reefs by cutting off room for growth and diminishing the amount of sunlight and oxygen reaching the coral.
Jim says urchins are like underwater gardeners.
“When sea urchins consume algae, they create open spaces on the reef that can be colonized by new coral babies,” he says.
Algae growth and coral bleaching have decimated coral reefs. The Keys have lost 80% of their coral in the past 30 years. Many factors are believed to contribute to coral bleaching worldwide, including pollution, climate change, warming oceans and overfishing. In the Keys, water temperatures are frequently over 85 degrees in the summer. That high water temperature prompts algae growth that can smother coral and inhibit the settlement of coral larvae.
Jim, a Columbus, Ohio, native, is so optimistic about the prospects for raising sea urchins that he turned down scholarship opportunities for graduate studies in Puerto Rico and at Bowling Green University in Ohio.
Jim’s father, Mike, was the Columbus Zoo and Aquarium curator. As a student at Bowling Green University, Jim learned that everything in nature is interconnected.
“If our oceans die, life in Ohio and landlocked states would also be adversely affected,” Jim says. “I knew coral reefs were in trouble, and I learned how important urchins were to the entire equation.”
Jim says the well-being of sea urchins has never been more important than now. Although once seen as a nuisance, the long-spined urchins are known as the greatest grazers of the Caribbean and caretakers of coral reefs.
The problem is, they are dying throughout the Caribbean. According to the National Park Service, long-spined sea urchins commonly live between the shoreline to depths over 100 feet. At low tide, they take shelter from waves in rock cavities. Although protected by the Florida Fish and Wildlife Conservation Commission, their numbers throughout the Keys have never been lower. Some scientists blame a microscopic, single-cell parasite for the die-off, which took hold in early 2022, but the resarch continues.
Jim describes one sea urchin species, Diadema antillarum, as a keystone species for Caribbean coral reefs. Before 1983, it was the most prevalent herbivore in the Caribbean. Today, it is nearly nonexistent.
“A diverse population of herbivores is important for maintaining a healthy balance between algae and coral on the reef and for supporting the many other organisms that rely on this ecosystem,” he says. “By restoring populations of different herbivorous species, we can help to support the health and resilience of Caribbean coral reefs.”
Jim hopes his urchin “babies” growing in an environment closely replicating the coral reef learn to eat algae off coral before being placed permanently into the wild. Every 15 to 30 days, he collects coral rubble covered in algae from the coral nurseries and puts it into the nursery with the baby urchins.
By grazing on the rubble, the young urchins learn to hide in the nooks and crevices of the reef. They also eat everything in their path, not just the algae.
“The dead coral has many things growing on it,” Jim says. “In this setting, the urchins get a much more diverse diet of alga types. They also get bits of calcium carbonate from the rocks, which makes their spines hardier and increases spine density.”
In Jim’s nursery—the first of its kind in the Keys—coral trees and urchin shelters hang on monofilament lines tethered to the ocean floor and are held upright in the water by a buoy. The nursery integrates repurposed materials such as ice cream buckets, crates, ceiling tiles and Gatorade bottles. The cages, which Jim designs, are made from vinyl-coated wire and PVC frames. Sea water can pass through the boxes while protecting the growing urchins from fish predators.
“We hope to create a low-cost method to rear thousands of these herbivores,” he says. “A mariculture system like ours could be a game changer.”
With hopes high for the success of his urchin family, Jim is optimistic he may be able to leave coral reefs in a healthier place.
“With this project, I get the strong sense that I can be part of the solution rather than the problem,” he says.
Virtually visit the nursery in this three-minute video: bit.ly/sea_urchin_nursery.
Sea Urchin Facts
- Urchins do not have brains.
- Beneath their spines, urchins have a shell called “tests.”
- Some species of urchins have been overfished because their eggs—uni or urchin roe—are popular at sushi restaurants.
- An urchin’s mouth, which is on the underside of its body, has five teeth.
- Urchins have hundreds of feet.