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Answer 1

A Dreadful Discovery About the Crown-of-thorns Starfish Contains a Silver Lining for the Great Barrier Reef
by Joseph McClain | February 4, 2019
Jonathan Allen has good news and bad news for Australians regarding the crown -of - thorns sea star.
The bad news is that the fecund and voracious destroyer of Indo-Pacific coral reefs has a previously unknown method of reproduction.
The good news is that the Australians might be able to limit outbreaks of these coral-munching echinoderms by using this new knowledge.
Allen is an associate professor in William & Mary’s Department of Biology. He is a member of a team that discovered that the crown-of-thorns seastar (COTS) can reproduce by larval cloning. Their discovery is described in “Larval cloning in the crown-of-thorns sea star, a keystone coral predator,” published in the journal Marine Ecology.


The crown-of-thorns is an infamous pest, responsible for the loss of immense stretches of coral throughout the Indo-Pacific region, especially on Australia’s Great Barrier Reef. It’s been the object of concern and media exposure for a couple of decades. Many people assume that because it does so much harm, the crown-of-thorns must be an invasive species, but it’s not.
“It’s native to the Pacific,” Allen said. “They’re widespread and we now know that there are four species.”
From an ecological standpoint, the crown-of-thorns have the same impact whether it’s a single species or four, he added. They’re all corallivores—coral eaters.
“And they pretty much exclusively eat coral,” Allen added. “They eat a lot of coral.”
“They get in what they think is a good spot,” Allen said, “then they kind of throw their stomach out of their mouth and just lie there and digest the coral outside of their body.”

Allen said that the crown-of-thorns are a natural part of the Great Barrier Reef ecology, but crown-of-thorns population explosions, known as outbreaks, put the balance out of whack. He said there has to be some set of environmental conditions that cause the crown-of-thorns population to go through the reef.

Mature crown-of-thorns reproduce sexually, a process that, like its feeding, is crude, but effective. Allen said the COTS have distinct genders, but there is no boy-meets-girl stuff.
“They’re basically bags of gametes. The males just emit sperm,” Allen said. “The sperm drift around on the current, rats along with chemicals that prime the females. The females release their eggs. Fertilization has a large random element to it.”
COTS sex won’t inspire many poets. And random and crude as the process is, it works quite well: The team’s paper points out that a single mature crown-of-thorns female can produce as many as 100 million eggs each year.
Scientists have found that many of those countless eggs were fertilized. Allen explained that advances in technology have allowed researchers to get a handle on the population of crown-of-thorns larvae, which are microscopic in size and drift along with the phytoplankton they eat.
Allen and his collaborators started thinking about larval cloning: What if those baby, microscopic starfish were out there on the reef in their uncounted gazillions, making copies of themselves?
It was an understandable oversight. Sexual reproduction of crown-of-thorns is so successful that larval cloning seemed superfluous. But, Allen and his collaborators were curious enough to begin watching larvae back in the lab at Orpheus Island Research Station in Australia.
They only recently were able to witness an act of crown-of-thorns larval cloning, even though they knew it was happening: “You put one larva in a beaker,” he said. “You come back the next day and there are two.”
They wanted to witness the stages of cloning, and clock the process. Despite their assiduity, for over a year they were unable to see an act of cloning. The watchword in the lab became “A watched larva never clones,” Allen said. Then one day, Allen was in the microscope room with one of the Australian co-authors.
“We were taking photographs and measuring these larvae,” he said. He was wielding his pipette, “And while I was putting this larva on a microscope slide, it just cloned! Right in front of me.”
“And it happened like that,” he said, snapping his fingers. “It explains why we don’t usually see it. It was essentially instantaneous. I was yelping and screaming.”

Answer 2

nvm.