In a World of Warming Seas, Feather Stars Might be Winners

The mesmerizing animals appear to be thriving even as coral reefs suffer.

Feather stars, those 200-million-year-old creatures that look like something straight from the pages of a Dr. Seuss book, may be the next kings of the reef. The plant-like animals seem to be thriving, even as other reef dwellers, like corals, are dying from warmer waters linked to climate change.

Angela Stevenson of the University of British Columbia has studied crinoids, a group of marine creatures including feather stars and sea lilies, for over a decade. She’s currently stationed in Negros Oriental, Philippines, where her team is observing and experimenting with the abundant feather star communities that live on the reefs offshore.

This feather star is one of the eight species being studied by Angela Stevenson and her team in Negros Oriental, Philippines.

PHOTOGRAPH BY ANGELA STEVENSON

The scientists are studying eight species of feather stars in shallow and deeper reef depths, tracking their relationships with the tiny shrimps, crabs, and snails that live on them as well as how quickly feather stars can regrow their limbs when they get lopped off.

Infinite Arms

That’s right: Feather stars can regenerate their limbs, seemingly indefinitely if they’re left in the water. Some species of crinoid can grow up to 150 arms; sever one and back it grows—slowly—at less than a millimetre per day at Stevenson’s research site.

Fish are the biggest consumer of feather stars, but the other small animals that live on feather stars are total mooches and will also occasionally snack on their hosts, too. Most of them don’t even bother to search for food, according to Stevenson; they simply wait until their feather star snags food particles on its sticky, Velcro-like arms and digests it, and then the slacker shrimp or snail will eat the resulting faeces.

Limb regeneration may be the reason why these living fossils have been, and continue to be, so successful after 200 million years of existence, Stevenson says.

“We’re unsure about their lifespan, but I'm starting to think these animals are immortal. They can pretty much grow back to their full size as long as part of their centradorsal (the central disk where all arms radiate from) is intact,” she says.

Warm Feathers

These incredible regenerating creatures also seem to be coping well with warming seas.

“We know some species seem to do quite well in warming temperatures,” Stevenson says. “They regenerate arms faster when we elevate temperature,” she says, referring to experiments raising temperatures by two degrees Celsius in the lab. Stevenson says she suspects that warming might be harming predators that would normally eat baby feather stars, allowing more stars to reach adulthood.

Meanwhile, oceans are steadily warming: NOAA’s quarterly “State of the Climate: Global Climate Report” for January through March stated that the global ocean heat content during that time was the highest in their records, which go back to 1955. That’s a trend not expected to reverse.

But in a world of warming seas, feather stars swim blithely on. Even if corals continue to die from sharply higher ocean temperatures, feather stars might just be fine, Stevenson says.

“I doubt the demise of coral will affect feather star populations,” she says. “All they need, really, are currents to bring food to them, and a substrate—any substrate—to perch on.”

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